27. 08. 2026 Will Steen

What is the deepest living fish?

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The deep Ocean has some of the least familiar and harshest environments on the planet. Which animals can be found here? What is the deepest living fish?

The Ocean is deeper than you think. On average, it is 3,700m (12,139 ft) deep. At its deepest point, the weight of the water above would be like trying to hold a blue whale in your hand.

The deeper into the Ocean we travel, we lose the energy giving light of the Sun, lose temperature and increase pressure. As the pressure builds, life becomes fundamentally more difficult. There is a limit to how deep Ocean animals can live.

How deep in the Ocean has any animal holding its breath gone?

Some of the most successful animals in the Ocean still rely on breathing. Dolphins, whales, seals and turtles all have to fill their lungs with air from the surface, as human swimmers do.

Despite this, some lung-bearing animals still venture deep into the Ocean.

What is the deepest a reptile has gone?

There are only a few reptiles to be found in the Ocean now – most of them are turtles. Like birds and mammals, reptiles have lungs to fill with air, tethering them to the surface.

That doesn’t stop the deepest diving turtle: the leatherback turtle (Dermochelys coriacea), the largest turtle in the world.

In 2006, a tagged leatherback turtle named T2 dived to a depth of 1,280m (4,200 ft) southwest of Cape Verde. Impressive. But no turtle can keep up with the mammalian divers.

Leatherback turtle is the deepest diving reptile.

What are the deepest diving mammals in the Ocean?

The sperm whale (Physeter macrocephalus) is renowned for its deep-diving exploits to hunt giant squid. One tagged individual was recorded reaching 1,202m (3,943 ft) in the Atlantic, but research using hydrophones to track the clicks sperm whales produce while hunting estimated dives as deep as 2,094m (6.870 ft).

Southern elephant seals (Mirounga leonina) are the most surprising champions of the deep Ocean. Large and clumsy on land, they dive up to 2,388m (7,834 ft) in some of the least forgiving waters on the planet; the Southern Ocean. Recent research has shown that elephant seals will go to sleep on these dives, spiralling gently downwards during their naps. How else do you sleep when you spend 8 months at a time at sea?

But the title of deepest diving mammal, and deepest diving animal with lungs, belongs to the Cuvier’s beaked whale (Ziphius cavirostris). One tagged whale ventured to a depth of 2,992m (9,816 ft) in dives recorded lasting as long as 137 minutes.

Pretty impressive, but most marine animals don’t have to come up for air. So, how deep can they go? Let’s start with one of the most successful and long-standing marine families: the sharks.

What are the deep-dwelling shark species? 

It’s very rare to find elasmobranchs below 3,000m (9,842 ft), only a few species can do it (we look at why later). The Greenland shark (Somniosus microcephalus) is the longest living vertebrate in the world, has been found as deep as 2,992m. A leafscale gulper shark (Centrophorus squamosus) was captured alongside a pale ray (Bathyraja pallida) at a depth of 3,280m.

Greenland shark is the longest living vertebrate

How deep was the deepest shark found?

The Guinness World Records  and most online sources give the title of deepest shark to the Portuguese dogfish (Centroscymnus coelolepis), with a recorded depth of  3,700m (12,139 ft). 

This is tied with another distinctive shark, the cookie-cutter shark (Isistius brasiliensis), also recorded at 3,700m. But these are not the deepest elasmobranch.

A ray, close relative of the sharks, was recorded even deeper – a Bigelow’s ray  (Rajella bigelowi)  was found at  4,156m (13,635 ft).

They could possibly be found deeper: while setting the record for a manned dive in 1954, legendary deep-sea explorer Lieutenant Commander Georges Houot  took an image of an unidentified dogfish, with their depth estimated as just over 4,000m (13,123ft). This could be another Portuguese dogfish, but there is no verifiable depth recorded, so it is not acknowledged as an official sighting.  

How deep can octopus live?

Most octopus like the shallow, coastal waters of the world. But not all. Dumbo octopus (Grimpotethis sp.) are deep-living octopus known for swimming using the fins on the sides of its mantle, making it “fly” like the fictional elephant. In 2020 researchers found a record-setter in the depths of the Java trench off Indonesia, at a depth of 6,957m (22,824 ft).

Like their coastal cousins, these octopus live on and near the seafloor. Finding one nearly 7,000m deep in the Ocean means octopus can live on 99% of the seafloor – only 1% is deeper than 7,000m.

In other words: the deepest parts of the Ocean only make up a very small fraction, and there is very little out of reach for their many arms.

How deep in the Ocean was the deepest fish ever found?

In 1970, a species of cusk eel (Abyssobrotula galatheae) was caught in an open trawl net that went 8,370m (27,460 ft) deep. Although it was hailed at the time as the ‘deepest fish ever found’, we have no way of proving it was caught at that depth, not as the net went down or came up. Therefore, we can’t say for sure this was the deepest fish.

The cusk eels (Ophidiidae) are one of only two fish families found below 6,000m (19,685 ft). The other are the snailfish.

Imagine a tadpole that is half a metre long and you have a good likeness of a snailfish (Liparidae). They are a family that can be found in shallow coastal waters, and seven different Ocean trenches, the largest depth range of any family. The snailfish are the champions of the deep.

In 2017, a new species of snailfish was described. The Mariana snailfish (Psuedoliparis swirei) is named after its home: the deepest trench in the Ocean, the Mariana trench, about halfway between Japan and Australia.

Initially it was found 7,966m (26,135 ft) down, but later that year researchers found one even deeper at 8,178m (26,830 ft).

Even that isn’t the deepest. A different species of snailfish with no common name, Psuedoliparis belyaevi, was recorded by remote video cameras in 2023 at a depth of 8,336m (27,349 ft) to take the crown of deepest fish in the world. For now.

Below the depth limit of the snailfish there is over 3km (1.86 mi) more water to the deepest part of the Ocean. What, if anything, can survive these depths?

The deepest fish in the Ocean. Posted by Ocean Generation, leaders in Ocean education. — Credit: Cusk eel by NOAA/MBARI, Mariana snailfish by DOI:10.11646/zootaxa.4358.1.7

What are the deepest living animals in the Ocean?

On the 23^rd January 1960, humankind took a trip to the deepest part of the Ocean for the first time ever. The bathyscaphe Trieste, carrying Jacques Piccard and Don Walsh descended nearly 11,000m (36,089 ft) down. When they reached the bottom, Jacques Piccard looked out of the window into the abyss and saw, despite everything, a flatfish “resembling a sole”.

Don Walsh recalled stirring up a lot of sediment, that remained the whole 20 minutes they were on the bottom. He said “We could see nothing. It’s like somebody painted the front of the window with white paint.” Not ideal for observing new Ocean life.

Neither Don Walsh or Jacques Piccard were biologists, and they were looking out through a tiny porthole into murky dark waters. In the years since, this sighting has been disputed, and is no longer considered a fish. But they had seen something. What was moving in the murk?

What did the first dive to the bottom of the Ocean see?

They didn’t see any fish. The most likely explanation for the “sole” they saw is an animal that can be found even at these deepest corners of the Ocean – a sea cucumber. An expert in trench biology suggested the species Galatheathuria aspera, which is white and oval shaped.

It showed that complex life had reached even here, the very bottom of the Ocean. More recent research has confirmed this.

Bathyscaphe Trieste,
a deep-diving
research submersible — Credit: U.S. Navy Electronics Laboratory, San Diego, California

What is the deepest animal ever found in the Ocean?

The deepest animal yet recorded is a species of giant amphipod: think of the sandhoppers that bounce around when you move some old seaweed on the beach, but over 30cm (11.8 inches) long.

A species of amphipod, Hirondellea gigas, has been found 10,897m deep. 185 of them were collected over a 3-hour bait deployment, suggesting that even at the bottom of the Ocean there is a surprising abundance of life.

The deep dive: What limits how deep Ocean animals can go?

For the air-breathing mammals and reptiles, the constraints are clear – they must return to the surface to breathe. The same is not true of sharks and fish.

By assessing the number of species of elasmobranchs (sharks and rays) we find at different depths, researchers predicted the maximum depth we would find a shark/ray at to be 3,893m (12,772 ft). The number of species decreases as we go deeper in the Ocean. The rate at which species decrease gives a rough idea of when there will be no species.

That number is an estimate, but the same method predicts bony fish to a depth of 8,350m (27,395 ft), which is also remarkably close to the actual depth they have been found. But what is preventing these animals from venturing deeper?

The secret may lie, ironically, with a compound used to enable living at depth.

What is TMAO?

Trimethylamine N-oxide, or TMAO, stabilises proteins in a fish’s body to help them retain their structure and function even at depth. Think of it as a mini engineer, preventing damage to the fish. Fish found deeper have higher levels of TMAO to battle the larger pressures. Makes sense.

But you can have too much of a good thing. Too much TMAO means the water balance gets disrupted. As a general rule, water travels to places where there is lower concentrations of water.

If there is too much TMAO in fish tissues, that lowers the concentration of water in the tissue below the concentration of water in seawater. Too much TMAO means water will start entering the fish and ‘drown’ it.

But if both sharks and fish face this issue, why are sharks found so much more shallow?

The deepest animal ever found in the Ocean is a species of giant amphipod — Credit: Daiju Azuma/Wikimedia Commons

Why are sharks not found deeper?

All findings suggest that elasmobranchs can be found up to and maybe just over 4,000m (13,123 ft) deep, but no further. Why are one of the Ocean’s most successful inhabitants limited to half its territory?

Ocean animals have to be careful about staying hydrated. As they are in constant contact with water, it is harder to retain the water they need to survive.

Sharks do this by retaining urea – a waste product excreted in urine – in higher concentrations to keep their tissues similar water levels with the seawater (some can change their body function to move between fresh and salt water – read more here).

They effectively make themselves as salty as the sea, so they don’t lose water. However, urea (like water pressure) can affect and damage proteins, making them malfunction.

So, sharks employ the mini-engineer TMAO here to counter the effects of the high urea levels on their proteins.

This means sharks have higher levels of TMAO in the shallows, so when they increase TMAO levels to survive in the depths they reach that critical level of TMAO concentration sooner.

Why do fish have a depth limit?

Fish don’t retain urea, they excrete it, which means they have to constantly drink seawater and use energy getting rid of the extra salt. It also means they don’t need TMAO to counter the effects of high levels of urea.

Fish then don’t need to increase TMAO levels until they are getting deep, so can reach deeper as their TMAO is only countering the effects of depth.

The maximum levels of TMAO allow fish to exist up to approximately 8,200m (26,902 ft) which lines up with observations. Going deeper would mean either the pressure of the water breaking the very molecules life relies on or bursting from water rushing into an over-salty fish.

No wonder the fish leave that last 3,000 m (9,843 ft) alone.

The Ocean is very deep, but still connected

Every record here comes with an asterisk – it is the deepest so far. Until recently we thought the depths were empty, but now we are discovering more species here than ever before: over 1,000 new species in a single year.

This is a world we are still only just beginning to understand, yet it is not separate. The deepest known animal, the amphipod Hirondellea gigas, has bacteria in its gut for digesting wood and plant matter that sinks from the distant land above.

Everything in the Ocean, from the air breathing divers to the deepest amphipods, are connected with our surface world. As we are to it.

Why are sharks not found deeper in the Ocean: Explained by Ocean Generation.

Cover image: The University of Western Australia

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Will Steen

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11. 08. 2026 Will Steen

How accurate is Shark Tale?

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Shark Tale was DreamWorks’ underwater adventure released in 2004, and is a real nostalgia hit.

But with the rose-tinted glasses removed we ask: How accurate is Shark Tale? Let’s start by looking at the characters:

**What Ocean creatures are the characters of Shark Tale? (in order of accuracy)**

Most accurate characters in Shark Tale

Sykes is a long-spine porcupinefish (Diodon holocanthus). Visually very accurate, bonus points that he ‘puffs’ up using water, rather than the usual mistake of making him puff up using air. 10/10

Oscar is a blue-striped cleaner wrasse (Labroides dimidiatus). Cleaner wrasse are indeed the cleaners of the reef, picking off dead skin and parasites, which he would eat. Oscar not having a fear of sharks would be accurate to his species, as they also clean sharks. 9/10

Crazy Joe is a hermit crab. His larger left claw singles him out as a left-handed hermit crab, and his striped antennae and relatively large size point to the giant hermit crab (Petrochirus diogenes). 8/10

Don Lino, Lenny and Frankie and most of their ‘mob’ are great white sharks (Carcharodon carcharias). The distinct countershading, strong jaws and notorious dorsal fin sell it, although there is a lack of claspers (see below). 7/10

The whales at the whale wash all appear to be sperm whales (Physeter macrocephalus). While not impossible to find sperm whales around a coral reef, it is less likely than a humpback or other whale species. Sperm whales specialise in diving deep for their food, not usually spending time in shallow, coastal waters where you would find a reef. They look right, just wouldn’t likely be there. 6/10

Shark Tale characters that missed the mark

Angie is an angelfish, but it isn’t clear what species she is. Her colouration most closely matches a pygmy Japanese angelfish (Centropyge interrupta), but it isn’t a strong match. 5/10

Ira Feinberg, or Don Feinberg, has markings identifying him as an elderly leopard shark (Triakis semifasciata). Leopard sharks are a lot smaller than great whites and also not found on coral reefs. 4/10

Ernie and Bernie, the Rastafarian jellyfish henchmen, fall into the same generic limbo that the Finding Nemo jellyfish do. The closest likeliness is a mauve stinger (Pelagia noctiluca) or a purple-striped sea nettle (Chrysaora colorata). Either way, the skeleton x-ray animation and sounds of electricity are misleading. Like bees and wasps, jellyfish stings are injections of venom rather than anything electric. 3/10

Luca is, judging by size, a Giant Pacific octopus (Enteroctopus dofleini). No other octopus comes close to the size of a great white. But these octopus are not found on coral reefs, preferring colder waters from California to Alaska and round to Japan. Generally, they are a rust-orange rather than Luca’s dark green colouration. We talk about his mouth later. 1/10

Lola is allegedly a lionfish. In character maybe – they are voracious predators, ambushing anything that comes across their path. Unfortunately, Lola doesn’t look much like a real lionfish. She is missing the characteristic spines and has no tentacles above her eyes or below her mouth. Lionfish don’t have a skinny waist in real life. 0/10

Are coral reefs underwater cities?

The opening shows off the base premise of the film: that a coral reef is a big underwater city. We love it.

Coral reefs house a huge variety of life, with an estimated 25% of marine species dependent on coral reefs. Small fish live in the nooks and crannies of coral and use it to shelter from predators such as the sharks, exactly how it is shown in Shark Tale.

At one point, a fish is dumping its rubbish into another fish’s mouth. This is key to how a coral reef functions. The clear blue water we love is like a desert for those living in it – clear because there is very little food floating around. On a coral reef, all the waste is recycled – one fish’s garbage is another fish’s food.

Coral reefs are underwater cities. Posted by Ocean Generation

Do whale washes exist in the Ocean?

Blue-striped cleaner wrasse such as Oscar do indeed carry out cleaning services on the reef, but for a much more varied clientele than just whales. The core concept of the whale wash is real, but there are some details that go astray in the movie.

1. The Whales. These cleaning stations are more commonly for larger fish and marine reptiles such as turtles. Whales and other cetaceans can use other skin care routines, such as rubbing on stones or leaping out of the water. To make Shark Tale more accurate, we would make it a Ray Rinse, a Shark Scrub, or the Fish Freshen.

2. The Cleaning. Oscar is a tongue scrubber in the film, but most cleaning would be focused on the skin – picking off parasites and dead skin and sometimes venturing into the mouth. He certainly wouldn’t use a brush, instead would be using his mouth. Maybe better they left that out of the film.

3. The Staff. Cleaning stations on the reef can have lots of different staff, from cleaning wrasse like Oscar to cleaner shrimp. There were a few in Shark Tale that you wouldn’t find on the real reef.

Turtles are customers, not cleaners.
Dolphins, whether real or sharks in disguise, wouldn’t be found at the cleaning station
Electric eels wouldn’t be anywhere near a coral reef, as they are freshwater fish. The only electric fish in the sea are the torpedo rays

Cleaning services exist on a coral reef. Posted by Ocean Generation, leaders in Ocean education.

What are the sharks in Shark Tale missing?

One anatomical inaccuracy shared between Shark Tale and its reef-based rival Finding Nemo is an important piece of shark missing. Don Lino and co are a little short down below.

Male sharks have two adapted extensions of their pelvic fins called claspers, which they use for mating. Just like our friend Bruce, a quick look at any of the sharks in Shark Tale leads to questions of immaculate conception. Maybe, as some sharks have been known to do, the sharks on Southside Reef are pros in asexual reproduction (producing young with only one parent). Or perhaps we have a cast of Carcharodon (great white genus) drag kings.

Male sharks have claspers. Posted by Ocean Generation. — *Illustration by Chris_huh via Wikimedia Commons*

Do octopus have mouths?

Luca is, judging by size, a Giant Pacific Octopus. There is one glaring error – as with all cephalopods, octopus have their mouths on the underside of their bodies, which house beaks. Giant squid (Architeuthis dux) have the largest beak in the animal kingdom.

Luca’s top-side trap is useful for animators to create recognisable emotions and speech (and create a brilliant background moment of Luca pouring and trying to drink tea) but a miss for accuracy.

**Who is in the Shark Tale mob?**

Don Lino, Frankie and Lennie are part of the great white shark family running a mob at odds with the reef. But their mob doesn’t make much sense.

Great white sharks do not typically socialise, and certainly don’t hang out with family, although new research does suggest that some populations do have socialite sharks, in South Australia and Guadalupe Island, Mexico.

The great whites are joined by some other sharks, leopard sharks like Ira Feinberg and great hammerheads (Sphyrna mokarran). Great white sharks don’t usually like other sharks and in fact are known to eat smaller species like leopard sharks.

The swordfish (Xiphias gladius) at the table would have similar anxieties. Great whites aren’t known to eat them, but their cousins the shortfin mako do. Great whites are unlikely mobsters, who don’t have a close family and have few natural allies.

The most likely mobsters are the orca (Orcinus orca). In the wild, orca maintain close family ties and cooperate to hunt and protect each other (and they have accents). A recent video showed a new example of this – one orca holding a sunfish still while another rams it. They can then eat the bits that fly off. Brutal.

But the orca in Shark Tale aren’t the orca of our Ocean. In the film they are goofy and scared, fainting when Oscar talks to them. In the real world, they eat swordfish and they are also known predators of great whites. They flip them upside down into a catatonic state called tonic immobility and then remove and eat their rich livers, leaving the rest. In reality, the orca would sit at the head of the table, ruling the Ocean mob.

Seabirds often harass other birds. Posted by Ocean Generation.

What other animals belong in an underwater mob?

If we were going to re-make Shark Tale (live-action reboot anyone?), what animals would we have in our orca-led mob? Frigatebirds, skuas and jaegers are seabirds that harass other birds to regurgitate their food, chasing and bullying smaller species such as terns.

There are excellent fish con artists. The bluestriped fangblenny (Plagiotremus rhinorhynchos) is dressed the same as Oscar’s blue-striped cleaner wrasse, but instead of cleaning will bite a chunk of flesh off. Butterfly fish have a dark eyespot towards their tail, to confuse predators which way they are facing.

Some fish are just as territorial as any mobster. Damselfish are underwater gardeners, cultivating their favourite algae, which they tend to diligently. They will protect their patch enthusiastically against all odds and any size of intruder. The same can be said of the Titan triggerfish (Balistoides viridescens). Ask any SCUBA diver – Titans demand respect. They fear nothing, and will regularly chase and bite large sharks such as tiger sharks.

The mob in Shark Tale is based around a species that doesn’t like family, would eat some of the species and could be eaten by others. There are a lot of good other marine mobsters to choose from.

**Do sharks live on the Titanic?**

The main gangster hangout in Shark Tale is none other than the wreck of the Titanic.

Wrecks are popular hangouts for fish and the large predators that frequent natural reefs. In fact, research suggests that wrecks could attract more travelling predators than natural reefs.

BUT. The real-life wreck of the Titanic is sat at 3,800m (12,500ft) deep, in the Northern Atlantic. Most of the mob could live that far north, but the depth would be an issue. Sharks are not generally deep-living marine creatures.

This image is from a study investigating the depths different shark species spend time at. White sharks were tracked to a maximum of 1277m (4,189ft). The deepest confirmed sighting of a large shark is a sleeper shark (Somniosus sp.) that was spotted by a remotely operated vehicle (ROV) at 2647m (8,684ft).

There are no large sharks in the Titanic. Scientists hypothesise that some elements of shark biology may prevent them from living in the deep, which we can explore another time.

How deep do sharks go - Explained by Ocean Generation. — Illustration via DOI: 10.1126/sciadv.abo1754

Do great white sharks go to bed?

In the film, Lenny is excited to find a bed to sleep on while hiding with Oscar. Now, you may know great white sharks don’t sleep on beds, but did you know they don’t even stop swimming to sleep? Let’s talk shark sleep.

For sharks (and all fish) to breathe, they must have fresh, oxygen-rich water move over their gills, just as we need fresh, oxygen-rich air moving over our internal ‘gills’ – our lungs. Some sharks can do this while stationary – forcing water over their gills using a technique called buccal pumping.

Great white sharks are among a group of sharks that can’t do this – they don’t have the nostril-like structures called spiracles behind their eyes which allow it. So, white sharks must keep the water moving over their gills through their movement – known as ram ventilation.

Research around sleep in these sharks is still lacking – we don’t really know what sleep looks like for them. But we know they don’t curl up in bed.

Are great white sharks cold blooded?

As Frankie is dying after being hit by an anchor, he tells Lenny “I feel so cold”, to which his brother helpfully replies: “but we’re cold blooded”. Frankie’s last word? “Moron”. That is probably because Frankie knew that great white sharks actually aren’t cold blooded.

Most fish are ectotherms – their body temperature is entirely determined by the temperature of their surroundings. Humans, along with all mammals and birds, are endotherms – “warm-blooded”, maintaining a favourable internal temperature utilising the heat produced by metabolism. Great white sharks, along with the other lamnid sharks (salmon sharks, mako sharks and porbeagle sharks), tuna and the leatherback turtle, are mesotherms.

What is a mesotherm?

A useful setup of blood vessels keeps the heat produced by the muscles in the system, rather than removing it with the deoxygenated blood. This is known as counter-current exchange.

This intermediary between the two means they can raise their internal temperature above that of their surroundings, but they do not have the high metabolic demand of being truly endothermic. The advantage is that these fish can work faster – these are some of the fastest fish in the Ocean. The leatherback can stay deeper for longer on its feeding dives before it needs to return to the surface to warm up.

Not cold blooded, but not warm blooded either.

Great white sharks. Posted by Ocean Generation.

Do sharks eat everything?

After holding Angie in his mouth, Lenny ends up throwing up a whole host of fun things. One of them is a number plate. This is based on fact: license plates have been found in the stomach of tiger sharks. This particular license plate is actually the exact plate Hooper pulls out of a tiger shark in Jaws, and that is discovered in the teeth of a tiger shark in Deep Blue Sea.

Other items include a radio, a violin, a beach ball and a broom.

Tiger sharks especially are nicknamed the rubbish bins of the Ocean and have been found with all manner of strange things in their stomach. A fur coat, a coil of copper wire, an unopened tin of salmon and a suit of armour are all among strange things recovered from shark stomachs.

Conclusion: How accurate is Shark Tale really?

Some of the core elements of the film are brilliant. The framing of a coral reef as a city is one we love – capturing the essence of so many species living and working together. The whale wash is a lovely idea, although making it a turtle wash, shark wash or any other large fish would have been more on the money.

But the shark mob, the Titanic and Lola the “lionfish” knock the accuracy score way down.

Verdict: Sleeping with the fishes… the dead ones. – Luca, 2004

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Will Steen

Does the Meg exist? Here’s what scientists actually found.

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31. 07. 2026 Will Steen

What kind of shark are you? (unknown sharks only)

What kind of shark are you? Posted by Ocean Generation

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A (slightly) scientific explainer about sharks

There are over 500 species of sharks. Some live over 300 years old, some glow in the dark. All of them have different vibes, so we’re asking – which kind of shark are you?

Pyjama Shark

In the temperate waters around South Africa, there is a small, stripey shark. The pyjama sharks live in the kelp forests, their small, slender bodies perfect for squeezing through the stipes and fronds in search of crustaceans, fish and other shark eggs.

Pyjama sharks are mostly active at night, but can come out in the day, especially if there is a lot of food, especially their favourite – squid. Usually, you can find them napping in crevices and caves with friends. If threatened, they will curl up in a ball to protect their eyes and heads. Relatable?

This is: the comfort-first homebody, whose ideal day is spent watching movies with friends and loads of snacks and maybe a nap or two on the way. They look great in stripes and hate horror films.

Megamouth Shark

The third biggest shark, but one of the rarest to be seen. Only a few hundred have ever been seen since its discovery in 1976, and we still have a lot to learn. Read more about the discovery of the megamouth and how we learn about these sharks here.

The megamouth shark has a huge mouth and big lips which it uses to eat mostly krill and plankton, sieving the water in a way more like a whale than a shark. They go on daily migrations between the darker Ocean depths and the shallows at night, following their prey. Only a few times have they been seen with another megamouth and tagging surveys suggest that males and females remain largely separate.

Given how few we have seen, the precise limits of their range aren’t known, but they have been found in waters near the equator all around the world, from California to Japan, South Africa to Australia.

This is: the gentle giant who looks quite intimidating but is actually just here for the snacks. Works the night shift, is the one that people have heard about but never see. Has a quiet dating life, but a great kisser (apparently).

Angular Roughshark

The angular roughshark doesn’t care much for your views of what a shark should be. It is bold and it is sharp.

Angular roughsharks have a luminous organ, maybe to help with camouflage, or maybe just because it can. Two big dorsal fins both have spines to deter predators, such as larger sharks or nay-saying energy drains.

They float around on the seafloor from 60m to over 1300m eating molluscs, crustaceans and worms. Look at the angular roughshark face head-on and you are looking at a triangle with a pig-like face and an attitude.

Angular roughsharks are found all the way up the eastern Atlantic, from South Africa to Norway, including in the Mediterranean. You know they would rock a fez.

This is: the one with thick skin, prickly and a bit intimidating when you first meet them, but it is just a real trail-blazing style. Trend-setter, not follower. Thinks running is weird, loves a seafood linguine.

Tasselled Wobbegong Shark

Living on reefs around Australia, the name of the tasselled wobbegong shark comes from the Aboriginal meaning “shaggy beard” referring to the skin flaps around their mouth. These are part of their incredible camouflage, breaking up their outline so they can lie in wait, sometimes using their tail as a lure, enticing an unsuspecting fish to get close enough.

This is: the funny one, rocking a funky, colourful shirt. Isn’t loud but will come through with a knee-slapper of a joke when you least expect it. Likes a laid-back lifestyle, believes good things in life will come to you. Fantastic facial furniture optional, but encouraged.

Frilled Shark

The frilled shark is an echo of the ancient Ocean. A slender, eel-like body is topped with ‘frilly’ gills and a mouth with around 300 needle-like teeth. These point back to trap soft-bodied prey like squid. Frilled sharks are another that’s rarely seen, as they usually live in deep water between 500 and 1000m (1640-3280ft). They are thought to ‘strike’ like a snake – lunging forward to grab prey.

Frilled sharks are found in depths around the world, preferring areas of the Ocean that are more biologically active with upwelling currents, such as seamounts.

This is: the old-soul, down to earth but not a big socialiser. When they do commit to something they are all in, no half measures. The one people describe as “an acquired taste”. Surprisingly athletic.

Greenland Shark

The Greenland shark is the longest-lived vertebrate on the planet. They can live over 270 years, possibly as long as 500 and don’t reach sexual maturity until approximately 150 years old. They are extremely slow swimmers, who cruise the cold, deep waters of the Arctic. The flesh of Greenland sharks is toxic to humans when raw due to high levels of urea and trimethylamine oxide, the compound that helps them live so deep.

They often carry an extra passenger – a parasite that dangles from their eyes. This may glow, attracting prey, but definitely does not help the Greenland shark’s eyesight. You win some, you lose some. Eyesight is overrated in the deep anyway.

This is: the patient one. No rush to do anything, is often late to things (we have all the time in the world!). Can be toxic if you don’t treat them right.

Epaulette Shark

Famous as the ‘walking shark’, epaulette sharks will use their pelvic and pectoral fins to walk around the coral reefs, including out of water at low tide to get between rockpools. The rockpools that were sanctuaries for small fish, crabs and worms are now hunting grounds, trapping them in when the tide gets low. Epaulette sharks can survive with almost no oxygen for hours by shutting down non-essential brain function.

This is: the one that can survive (and thrive) on shockingly little sleep/coffee. They are adaptable, can and will get where they want to using any means necessary. Often turns up unexpectedly, usually looking for food.

Still not sure which you identify most with?

Maybe our cards will help you decide – do you agree with our scores?

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Will Steen

Does the Meg exist? Here’s what scientists actually found.

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15. 07. 2026 Will Steen

Does the Meg exist? Here’s what scientists actually found.

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Yes, the Meg exists. No, it isn’t the one you are thinking of.

On the 15^th November 1976, the US Naval Research ship with the catchy name AFB-14 was on a mission 42 km (26 miles) off the coast of Oahu, Hawaii. Suddenly, the sea anchor, a parachute-like tool for stabilising a ship at sea, caught and pulled. The crew hauled it up to find 4.5m (14.7 ft) of fish.

The crew brought the 750kg (1,653.5 lbs) shark on board with “much difficulty” and brought it back to Kaneohe Bay, tying it alongside the dock overnight.

The shark was so heavy it needed a Navy crane to lift it. During the operation the caudal fin (tail) broke off, dropping the shark into the water where it needed recovery by divers. Finally, though, it could be examined by the experts.

Amongst the first on the scene was the director of Waikiki aquarium, Leighton Taylor. Along with other marine biologists, they recognised a species that was entirely new to science.

Leighton Taylor had the honour of naming the species, and settled on Megachasma pelagios – from the Greek meaning “the large yawning hole of the open Ocean”. It is known more commonly as the megamouth shark – the largest shark you’ve probably never heard of.

50 years on, what do we know about this elusive shark? And after discovering this, does that mean there could be other huge shadows lurking in the depths?

US Navy Ship retrieving the first megamouth shark. — *Photo via California Academy of Sciences*

What does the megamouth shark look like?

As the name suggests, the main feature of the megamouth is its vast mouth, which is housed in a huge bulbous head. This mouth is full of tiny teeth, not big white sharp things like its cousins, leaving the megamouth with a gummy grin. The tail also deserves a mention – similar to the thresher shark, the megamouth has a large upper lobe of its tail, which can be as big as a person.

The megamouth is the third biggest species of shark behind the two other filter feeding sharks – the whale shark (Rhincodon typus) and the basking shark (Cetorhinus maximus).

Megamouth sharks can reach sizes of up to 8.2m long, maybe up to 9m, with females reaching larger sizes.

What is filter feeding?
Filter feeding is utilised by animals of all different shapes and sizes in the Ocean. The premise is to filter out the tiny algae and animals floating in the water. Whales do this using their baleen, flamingos with their special beaks, and most forage fish have gill rakers, catching anything in the water moving over their gills.

Whale sharks, basking sharks and megamouth sharks are filter feeding sharks. — *Megamouth shark photo by Bruce Rasner*

On the 14 November 2023, a stranding gave us amazing insight into the reproduction of the large-lipped fish. A female megamouth was washed ashore while giving birth. 1 pup was found next to her, with 6 more in her belly. They measured 1.65m to 1.83 m (5.41-6 ft) long. That is approximately one Ocean Generation Marine Science Officer (not a scientifically accepted measurement) long.

The first descriptions of megamouths are less than kind. A “soft, flabby body and fins, low-flow branchial filter apparatus and small gill openings”. Taylor suggested that this pointed to an animal far less active than the other filter feeding sharks.

To confirm this, we had to find a live one.

When was the first live megamouth shark found?

On October 21, 1990, the sixth megamouth shark ever was found, caught up in a drift gill net off California. The big difference with megamouth number 6? He was still alive. We shall name him Luis, after the Luiseno people indigenous to the Californian coast he was caught off.

When the fisherman, Otto Elliot of the vessel Moonshiner, pulled up Luis, he recognised that this was a rare find. He managed to get a rope around the peduncle of the shark (the base of the tail) and towed it for five and half hours back to harbour.

Otto was asked by scientists to keep the shark alive until measurements had been taken, and so Luis was left tied by a short tail rope in the harbour. Quite remarkably, Luis survived.

The researchers formulated a release plan, and towed Luis back out to open water. Here, he become the first live megamouth shark to be filmed, and was released with a tag, giving us nearly 51 hours of insight into the lives of these mysterious sharks.

What did we learn from tagging megamouth number 6?

The research vessel R/V Discovery was assigned to tracking Luis, ensuring it was collecting data from his tag. It wasn’t difficult to keep up – Luis cruised at around 1.15 kilometre (0.73 miles per hour), although a current going against him led scientists to estimate his true speed: 1.5-2.1 km/h (0.73-1.3 miles). As predicted by the initial discovery, Luis was no speedster.

Luis showed us that megamouth sharks follow a crepuscular vertical migration: crepuscular meaning at dawn and dusk, vertical migration meaning moving up and down. He spent his days in the depths around 150m (492 ft), returning to shallow waters of around 20m (65.6 ft) during the nighttime. Luis used the light (or more accurately the dark) to guide his movements: a sharky anti-moth.

Why was he making this migration every day? Could he be chasing food?

What do megamouth sharks eat?

Researchers can use the chemical properties of tissue from an animal to work out where it has been eating, and what it has been eating.

A large study compared the diet and location of 91 megamouth sharks and 90 whale sharks.

Whale sharks tended to eat up the food chain as they got bigger (and older): they moved from phytoplankton to fish to bigger fish and so on. They had a far more varied diet than our mega-mouthed friends.

The very first megamouth was found with a stomach full of krill, and this was no coincidence. Megamouths love krill and jellyfish and that is kind of it. No matter how big they get, they don’t grow out of their krill phase. Imagine being stuck with that food you were obsessed with when you were young, for life.

The researchers also found that male and female megamouths were quite distinctly separated – they were eating in different places.

Why? We aren’t entirely sure yet, the researchers suggested that males may roam further to find mates while females stay in the productive, safer waters near birthing grounds. There is still plenty to find out about these secretive sharks, but why are they so good at remaining hidden?

Why do we not see many megamouth sharks?

The Ocean is huge. Think of an Ocean creature – starfish, seahorse, the famous clownfish (find out how scientifically accurate Finding Nemo actually is here). Chances are, you are thinking of a coastal animal, that we land-dwellers cross paths with regularly.

The megamouth is from a different world, that we are not regular visitors to. During the day, they cruise through the darkness of the twilight zone, and only at night do they come more shallow. There are only nine sightings of megamouths in natural conditions – humans and megamouths don’t overlap.

230 of the 301 sightings (as of June 2026) come from megamouths caught up in fishing gear. And we are seeing more. 170 of the 301 megamouths ever found came in the last ten years, 131 coming in the 40 years before that. Why are we seeing more now?

Given the large portion that are found due to fishing, the increase is likely to be related to fishing. Maybe an increase in fishing activity is seeing more caught, or new equipment at different is catching more megamouths. Or maybe these fisheries have always caught megamouths, but the reporting of the catches has got a lot better. Being aware of our impact on the Ocean is the first step to controlling it.

Anyway, now we know there is a massive, nearly 10m (32.8 ft) shark swimming around out there that we only discovered 50 years ago: there is only one question to follow that.

Is the megalodon still alive and hiding in the deep?

No. There are two main reasons for this.

1. Amount of food – can’t hide the evidence.

An active hunter that is estimated to have been over 24m (78.7 ft) long, the megalodon had huge teeth which it would have used to eat other sharks, fish and whales. Prey species like whales are mostly found in the surface Ocean, increasing the likelihood of even the stealthiest hunter being seen.

If not seen directly, the effects of having a huge hunter would be visible. Bite marks and teeth would be regularly spotted, and they aren’t. We haven’t found a megalodon tooth younger than 3.5 million years old, which is when we think megalodon went extinct.

2. Location – megalodon isn’t hiding in the depths.

We know megalodon was a tropical and subtropical dweller, that thrived in the warm waters. Suggestions that they could be hiding in the cold, dark depths of the Ocean are impossible. Especially when we consider the compound that protects sharks’ cells from the crushing pressures of the deep Ocean stops being effective around 3,000m (1.81 miles), suggesting that sharks absolutely can’t go below 4,000m (2.5 miles) deep.

The megamouth is a big shark, but smaller than megalodon, and eats tiny prey that lives in the pelagic depths (deep, open water). That is why it wasn’t discovered for so long.

Megalodon jaw, posted by Ocean Generation. — *Photo by JJonahJackalope via Wikimedia Commons*

Could there be another huge species of shark still undiscovered?

We can’t rule it out completely (the Ocean is on average 3,682m (2.28 miles) deep – plenty of space for something to hide), but it is unlikely. We understand our Ocean more than ever, and large species would have been found if not by scientists, by the commercial fishing fleets that drag nets through most layers of the Ocean.

The most likely shark hiding out there would be a sleeper shark, similar to the Greenland shark. As the name suggests, these fish like life in the slow lane, cruising the Ocean depths for food. Their un-rushed lifestyle means low demand for food, and they can survive on less food, such as occasional whale falls (read more about how a dead whale means new life in the deep here).

What do we still not know about megamouth sharks?

There is plenty we still have to discover about megamouth sharks. Why are they usually separated like a school disco, the boys and girls staying far apart from each other? Do individuals migrate like whale sharks, or have their favourite spots they stay in? Do they have glowing mouths to attract prey?

How do they hunt? Is it like basking sharks, swimming with mouths agape? Or whale sharks, opening mouths quickly to create suction, drawing prey in? Or something else, more like a whale drawing its large mouth over prey?

The megamouth story is full of mystery and excitement. It also shows us our increasing presence in the Ocean. It does not mean the megalodon is still alive. That mystery has been solved. Trust us.

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Will Steen

Does the Meg exist? Here’s what scientists actually found.

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7. 07. 2026 Will Steen

The lonely whale: The story of the 52Hz whale

The story of the world's loneliest whale, the 52Hz whale: explained.

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There is a unique whale song echoing through the Ocean, sung by the loneliest whale in the world. What kind of whale is it, and is he actually lonely?

The Ocean used to be thought of as noiseless. Legendary Ocean explorer Jacques Cousteau’s first book was named The Silent World. Swimming comes with ears full of water, muffling the familiar noises of the airy world above.

Only recently, and mostly by accident, have we begun to realise that the Ocean is far from silent. Noisy coral reefs call in larvae to settle, fish grunt and whistle at each other, and snapping shrimp fill the water with a white noise any focus app would be envious of.

The most famous of the Ocean songs is that of the whales.

How we discovered sounds in the Ocean

In the second half of the 20^th century, the Ocean became the frontline of the Cold War. Submarines glided through the depths, carrying enormous destructive power but hidden from sight. In the Ocean, sound matters more than sight.

We began listening to the sounds of our Ocean, to keep track of those sneaky submarines, and discovered a new world we didn’t understand.

In March 1949, R/V Atlantis from Woods Hole Oceanographic Institution picked up some strange noises off the coast of Bermuda that couldn’t be identified. A haunting, eerie noise that could be mistaken for a wolf’s howl over the mountains. The noise was archived, unidentified.

1949 also saw bio acousticians William Schevill and Barbara Lawrence record beluga whales in Saguenay River, Canada. This was the first time that cetacean (whales and dolphin) noise had been identified.

William Schevill was later credited with diverting geopolitical catastrophe:

“Bill helped defuse a tense moment between the USA and Soviet Union during the Cold War. The US military suspected that low frequency blips were being used by the Soviets to locate American submarines, whereas Bill showed these were produced by fin whales (Balaenoptera physalus) hunting prey.”

He wasn’t the only one battling misunderstood Ocean sounds. You can read about how herring farts nearly ended the world here.

In a naval listening station from the late 1950s into the early 1960s, engineer Frank Watlington was listening out for the sounds of submarines in the Atlantic. He would regularly hear rich and emotive melodies echoing around the Bermudian waters. He recognised the sounds as biological and recorded them, hoping to one day identify the singers responsible. He didn’t have to wait long.

Who identified humpback whale song?

In the mid-1960s, a biologist who had focused on echolocation in bats and the hearing of owls turned his attention to Frank’s recordings. His name was Roger Payne, and he was the man who would take the songs of the sea to ears around the world.

Payne analysed the recordings and identified the singers: humpback whales. He published a scientific description of the songs Frank had recorded in 1971, revealing their complex structure and rhythm. But a peer-reviewed scientific paper wasn’t going to make big enough waves (pun intended).

In August 1970, before that paper had been published, Roger Payne released the Songs of the Humpback Whales, a vinyl record just under 35 minutes long of simple, unaltered whale song. The sound took the world by storm.

But even this record paled in comparison to a further honour, bestowed two years earlier in 1977. The Voyager spacecraft left the Earth’s atmosphere with a golden record – a phonograph filled with details about humanity and life on Earth, should the spacecraft ever reach distant life. Track 3 on the record was: “United Nations Greetings/Whale Songs (Various Artists)”.

The songs of the humpbacks were part of the exclusive package: the first man-made materials to leave the solar system, which it managed in 2012. Cetacean song was cemented as a defining element of our planet.

When was the 52 Hz whale first heard?

The wonder of the whale song increased as we listened and learned more – they evolve and spread culturally between and across populations.

Looking through a human lens, we can see similar cultural transmission. Gangnam Style had people trying to sing Korean around the world in 2012, and schools across the Western world are currently shouting “six-sevvvan”. Orcas? They have fashion cycles of wearing salmon as hats.

For humpbacks in the South Pacific, the song writers are off the eastern coast of Australia. Their songs can travel across the largest part of the Ocean to be sung by whales off the coast of Ecuador.

In 1989, a song was recorded that piqued the curiosity of biologist William (Bill) Watkins. The singer became known as the 52 Hertz whale, or as we will use, 52.

To understand why it stood out, we need to first explore sound.

What is sound? What can humans hear?

Sound has two basic properties: frequency and volume. Frequency translates as the pitch we hear – higher pitched sounds have higher frequencies. Frequency is measured in hertz (Hz).

Different animals have different ranges of hearing – some can hear higher frequencies, some lower. Humans are credited with a hearing range of 20Hz-20,000Hz, most sensitive from 2-5,000 Hz. Human speech is approximately 90-135Hz for an adult male and 160-240Hz for an adult female.

You can test your hearing range by listening to this video going through different frequencies – see how high you get.

The humpback whales typically sing in the range of 80-4,000Hz, perfectly within our auditory range. Different animals use different frequencies to communicate: there is a whole world of noise that exists outside of our range of hearing.

Blue and fin whales produce songs of much lower frequency, slipping below our range of hearing (known as infrasound). Others, such as sperm whales and bottlenose dolphins, will use higher frequency clicks in echolocation that we can’t hear (known as ultrasound).

A spectrogram is a
visual representation of sound.

Why is the 52 hertz song so special?

The song we played earlier has been sped up by 10 times so we can properly appreciate it in our range of hearing. It would ordinarily be at the very bottom end of our hearing.

Blue whales will typically call between 10 and 40 Hz, soulful moans that would vibrate your entire body. Fin whale vocalisation is focused around 20Hz pulses, low chirps echoing through the blue.

So when the hydrophones picked up a call focused around 51.75Hz, it didn’t fit. Too high for blue and fin whales, but too low to be a humpback. This whale was singing its own tune.

Listen to the 52 Hz whale recording

Audio courtesy of NOAA PMEL.

For 12 years, Bill Watkins tracked the whale he had dubbed the 52Hz whale, or 52.

The 52 Hz whale sings in a different range to most other whales

What do we know about the 52 Hertz whale?

He published his findings in 2004, tracking the source of the unique song. He made some intriguing discoveries:

Daily travel distance: 52 was a mover. Across the 12 years of seasonal tracking, the whale averaged 47 kilometres every day, and up to 69 km per day.
Seasonal travel distance: A real mover. In the 1992/93 season, 52 travelled just 708km. But across all the tracked seasons, the average distance travelled was 5,518km. In 2002/03, 52 travelled 11,602km. If you ran a marathon every day, it would take you 275 days to cover that distance.
Time spent with other whales: 52, whether intentionally or not, is a solo rider most of the time. The calls were separate from other closely monitored whale species – blue, fin and humpback.
Time spent in one place: 52 is a true nomad. In Bill’s words: “There were no apparent repeated patterns to the whale’s travel”.
Deepening singing: As is normal with whales (and humans) the distinctive voice of 52 deepened by about 2Hz over the study period.
Daily singing time: On some days, 52 sang for over 20 hours.

Map showing the area where the 52HZ whale had been tracked. — *Credit: The Washington Post*

The Symbol: The story of 52 captured the imagination far beyond the scientific community.

The paper caught the eye of a young science journalist, Jon Copley, who covered it in the New Scientist magazine, with the title “Lonely whale’s song remains a mystery”.

A New York Times article by Andrew Revkin built on this theme, painting the picture of a whale roaming the Ocean, calling out in a voice none could recognise, its song going unanswered.

To add melancholia of the whale’s song, Bill Watkins, the great listener and tracker of 52, died in 2004, a month before his paper was published. He would never see the impact his work had.

And it certainly had impact. The idea of a lonely, misunderstood whale resonated (sound joke) with the wider public.

A quick search of lonely whale will uncover endless articles, Facebook groups, TikToks, Reels, and videos exploring the legend of 52 (not all accurately). So, what do we know about this whale?

The Symphony: Is the 52 Hertz whale actually lonely?

Is 52 Hertz lonely? The short answer: we don’t know, but probably not.

The tracking study from Bill Watkins suggests 52 didn’t tend to hang out with other whales, preferring to meander and migrate on their own. But we don’t know how unusual that behaviour is. 52’s unique calls have allowed one of, if not the most detailed long-term tracking studies of any single great whale. It might not be unusual for a whale to spend a lot of time alone.

To clear things up – the other whales can still hear 52. They might just sound a bit strange, like a human talking after inhaling some helium at a birthday party.

One of the lead theories behind the 52 hertz whale is a hybrid between a fin and blue whale. These hybrids have been documented, and fin and blue whales are known to aggregate together on the west coast of North America.

The documentary The Loneliest Whale: Search For 52 set out to find the maverick cetacean singer. The team didn’t prove that 52 was a hybrid but did document a hybrid whale in amongst other blue and fin whales.

This hybrid was documented 20 times over a 16-year period, and at times with over 30 blue whales. IF this is our whale, they have plenty of friends.

Another twist – in 2010, two separate listening stations picked up calls in the 52 hertz range. Could there be another whale hitting the same notes out there? We don’t yet know for sure, but we like to think so.

Different whale species sing at different ranges. Posted by Ocean Generation

What’s next for the whales?

52 is certainly not alone in his sound-based struggles. The Ocean is a much noisier place than it used to be. Ships criss-cross the Ocean carrying food and goods between countries, and they are not subtle. Huge air guns fire, sounding out the seabed to find reserves of oil and gas. Piledrivers pound foundations for offshore constructions such as wind turbines.

The noise they produce creates an acoustic fog, making it harder for whales to communicate. One study estimated that North Atlantic Right Whales have lost over 60% of their communication space. Another shows that they have to ‘shout’ over the noise of propellers churning the whale’s waters. In the aftermath of 9/11, there was a significant drop in ship traffic and thus the noise they produce. Researchers examined whale poo and found less stress-related hormones in the excrement during this time: less noise = less stress.

Our noisiness is making all whales a bit lonelier (and a bit more stressed).

Fortunately, noise is one of the easiest pollutants to fix. Engines and propellers are getting quieter, and shipping slowdown areas where there are whales have reduced the acoustic intensity by 70%. We could see an Ocean far less impacted by our noise in the near future.

How has whale song connected us to the Ocean?

The discovery of whale song connected us to these Ocean giants like never before. The Songs of the Humpback Whale helped launch the Save the Whales campaign, ending industrial whaling.

52 has prompted songs, such as 52 Whalien by K-pop band BTS, tattoos, sculptures and stories. Wherever the story goes, there is an outpouring of sympathy and empathy. So many have found empathy, understanding and connection with 52.

The more we have listened to our Ocean, the more we have discovered, and the deeper our connection has grown. 52 has been a focal point for the misunderstood and unheard. But, as his popularity has shown, we aren’t as lonely or misunderstood as we may believe – and maybe 52 isn’t either.

Quick questions.

What kind of whale is 52 Hertz?

We don’t know for sure. Scientists have suggested a hybrid of a blue and fin whale, or one of those species with a slightly different morphology.

Where does the 52 Hertz whale live?

The calls of the 52 Hertz whale have been recorded off the west coast of North America, from Alaska to California and further south to Mexico.

Is the 52 Hertz whale alive?

Most likely. We first heard these calls in the 1980s, and whales live a long time. Blue and fin whales can both live over 100 years, and we likely don’t know just how long they can live because industrial whaling lowered the life expectancy of whales considerably.

Is the 52 Hertz whale lonely?

We don’t think so, although loneliness can be difficult to spot. Check in on your friends.

Post by

Will Steen

Does the Meg exist? Here’s what scientists actually found.

Monthly: Impact in your inbox.

12. 05. 2026 Will Steen

How did fish farts nearly end the world?

How did herring farts nearly end the world?

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Fish don’t even fart. Let’s talk about the time that not knowing about the Ocean, or herring (a fish), nearly kicked off World War 3.

The Cold War was dotted with moments that brought humans closer to annihilation than ever before. Checkpoint Charlie, the Cuban Missile Crisis and various satellite proxy conflicts all presented opportunities for humanity to self-destruct.

1981 was witness to one of the best named incidents – the Whiskey on the rocks incident.

What happened during the Whiskey on the rocks incident?

On 27 October 1981, S-363 – a Whiskey-class submarine from the Soviet Union – ran aground in Swedish waters.

The defence presented by the Russians emerging bashfully from the beached boat was navigation failure. One that had mysteriously taken them through the complex topography (seabed features) and within ten kilometres of one of the most important naval bases in Sweden.

The Swede’s were (understandably) sceptical. Later, the Soviet story changed, claiming the vessel entered Swedish waters due to being in distress.

Increasing the tension, Swedish radiation detectives concluded a high likelihood of the submarine carrying nuclear weaponry – a challenge the Soviets did not deny.

Whether or not they intended to be there, with whatever weaponry, the incident showed Sweden and the world that Soviet submarines were active within Swedish waters. Where there was one, there could be more.

Listening for danger

As a result, the Swedish Navy were on high alert, listening and watching for more intruders. Intruders they kept finding.

Finding submarines isn’t an easy business, especially in the often-murky waters around Sweden. When you can’t rely on your eyes, use your ears. Sound travels four to five times faster (and further) in water than it does through air, due to the increased density of water.

Submarine warfare led to the development of underwater listening technology, using underwater microphones: hydrophones.

A hydrophone is a microphone specially designed to listen to and record sound waves underwater.

Hydrophone being deployed in the Ocean. Posted by Ocean Generation. — Photo by Dave Mellinger/Oregon State University

Over the next decade, there were several high-profile submarine hunts, as hydrophones picked up the sounds of a submarine, which were chased, cornered and showered with depth charges (bombs set to explode at certain depths).

But no hits were recorded, and no traces of the underwater invaders were found. The Russians maintained: there were no submarines.

The fall of the Soviet Union in 1991 saw a global de-escalation in tensions. The Swedes expected a let up in their little hide and seek game.

Yet the Swedish navy continued to chase Russian submarines they could hear in their waters.

By 1994, the Swedish prime minister had enough and sent the President of Russia, Boris Yeltsin, a complaint, asking him to reign in his navy. Yeltsin maintained that there were no Russian submarines entering Swedish waters.

The Swedes began to question – what if the Russians were telling the truth?

How were the Swedes detecting submarines the Russians swore weren’t there?

The listening stations in Sweden had two sounds that signalled the presence of a Soviet submarine:

kavitationsljud or “cavitation noise”, produced by a propeller ripping up the water, making air bubbles that pop as they collapse;
typljudet, or “typical sound”. The typical sound was a crackling sound, likened to that of frying bacon, thought to be produced mechanically.

If either of those noises were heard, it was labelled a sure-fire incursion. The producer of the noises, however, was no nuclear submarine.

The Discovery: Fish farts that nearly caused WW3

In July 1994, another Russian sub was detected by a sonobuoy – specifically, the cavitation noise was heard.

A sonobuoy is a small floating device that has a radio transmitter above water and a hydrophone array below, able to listen and transmit what it hears.

Sonobouy
being deployed. Posted by Ocean Generation, leaders in Ocean education. — *Photo by sonobuoydude*

This time, another vessel was in the area to investigate immediately.

What did they find? A small, otter-like animal called a mink was observed swimming near the sonobuoy. The cavitation noise had not been the four-bladed propellers of Russian submarines, but the four legs of exploring mustelids swimming between isles of the Swedish archipelago.

Mink is a semi-aquatic animal. Posted by Ocean Generation.

Following this, in 1996, the military invited some bio acousticians (experts that listen to nature) to analyse the typical sound.

Magnus Wahlberg and Håkan Westerberg were the academics brought in, the first civilian ears to hear the sound that had haunted the Swedish Navy for fifteen years.

The noise coupled with reports of bubbles seen at the surface when the typical sound was heard gave the scientists an idea. To test it, they went to the local fishmonger.

They bought a herring, a small, schooling fish. The herring was immersed in a bowl of water alongside a hydrophone and squeezed.

From the rear end of Sweden’s national fish came nothing other than the typical sound.

The Swedish Navy had been depth charging some chattering fish: Clupea (see below).

What are herring?

Herring (Clupea harengus) are among the most abundant fish in the world. Their name may be sourced from the Old German heri meaning “host, multitude”, reflecting their habit of gathering in vast shoals.

Herring reach up to 45cm long and can live for up to 25 years. They typically stick to coastal waters up to 200m deep. The fifth most-caught fish by weight globally, herring have been an important source of food for humans for a long time.

Interestingly, herring have a very good sense of hearing. Initial theories were that this could help them avoid cetacean predators such as orca and dolphin who use echolocation to hunt.

How do herring make noises like a submarine?

In 2004, researchers set out to find out more about the herring and the noise from their rear end. They captured some wild Pacific and Atlantic herring and recorded them using hydrophones.

The scientists recorded and categorised the typical sound: bursts of 7-65 pulses lasting between 0.6 and 7.6 seconds, with frequencies ranging from 1.7Hz to 22kHZ. This herring harmony was named: Fast Repetitive Ticks, or FRTs for short. Who says scientists have no sense of humour?

To investigate the reasons for the noise, they ran several scenarios. Some fish were being fed and some deprived food. There was no change to the number of FRTs between the groups.

Herring is a small schooling fish. Posted by Ocean Generation, leaders in Ocean education. — *Photo by Hunter Stevens*

So: these noises are not “farts” at all.

Listen to the noisy herring here.

Researchers then blacked some of the fish from access to the surface, to see if the FRTs were from gulped air being pushed through.

On the first night, there was no significant change, however when the trials progressed for a second and third night, FRT production dropped significantly. It seemed the herring did need air access eventually to ‘recharge’ their FRT tanks.

The tanks themselves were surprising. The researchers concluded that the FRTs were produced through expelling air from their swim bladder out of their anus: “a form of sound production not… previously described in fishes.”

Why do herring ‘fart’?

Not a by-product of digestion, so why would some small fish squeeze air out of their swim bladder?

Buoyancy regulation was suggested, as the swim bladder is predominantly used to adjust how ‘floaty’ a fish is – more air will mean it floats closer to the surface. However, fish kept in shallow tanks had no need to alter their buoyancy yet were merrily FRT-ing. It wasn’t buoyancy either.

Herring have long been known for their exceptional hearing. Maybe, then, they produced this noise for each other’s benefit? The fish were not in breeding condition, so they knew it wasn’t a mating function. Researchers separated them into tanks with different numbers, from 1 to 30. The number of FRTs each fish produced increased when they were around more herring, implying that there was a social function.

They dug even deeper. They found FRTs were mostly produced at night (specifically between 23:00 and 00:00). Was it a stress signal? The herring produced no FRTs during tank maintenance, but to make sure they took it a step further.

The researchers took water from another tank, one that contained a “high density” of spiny dogfish (Squalus acanthias) and added it to the herring tanks, filling them with sharky smell. It did not draw even a startled squeak.

Off this evidence, the researchers suggested that FRTs are not a stress or mating response, but purely for social contact – particularly maintaining cohesion in darkness.

Anatomy of a herring, edited for clarity by Ocean Generation. — *Klink-hard (1996) via Wahlberg and Westerberg (2003).*

In many ways we are lucky that it was the Swedes combating these ephemeral Russian submarines. This peaceable country hasn’t fought a war since 1814 and has never had nuclear weapons (although had a programme exploring the possibility until 1968). A more hot-headed geopolitical player could have taken things more personally and escalated beyond a strongly worded letter. Fish “farts” really could have ended the world, and we never would have worked out they aren’t even farts.

Thankfully, Sweden put curiosity first and went from a stranded submarine to bubbling butts to a deeper understanding of communication and social structure in the humble herring. Who knows what more listening in the Ocean could reveal?

Cover image by Henry Zbyszynski

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Will Steen

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22. 04. 2026 Elliot Yu

The oldest things in the Ocean: Explained.

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What do we mean when we say the “age of the Ocean”?

It could mean many things, from the oldest living thing in the Ocean to the time at which the Ocean first formed. Since there is no official definition, we can have some fun with stretching the definition of “age of the Ocean” by looking at some of the oldest things in the Ocean.

What are the very young things in the Ocean?

First, we stop off what I will call the “very young” section. These are on timespans of one to just above one thousand years. While these things are by no means short on a human timescale, they definitely are relative to the oldest things on this timeline. Most of this section is made up of animals, though not all.

We can interpret the “age of the Ocean” as meaning the oldest living thing in the Ocean.

What’s the oldest vertebrate in the Ocean?

One contender is the Greenland shark. The oldest measured was 272 years, but they are thought to be able to live to 500 years. For perspective, the oldest person ever lived to 122 years old. The Greenland shark can be found in the North Atlantic, being the largest fish to live in Arctic waters. The females of the species can grow to 4-5 metres, about the length of a small car!

These animals grow incredibly slowly and live for a long time. However, this age takes us nowhere near even the oldest living animal. We can still give the Greenland shark the title of “the oldest vertebrate” though.

One of the oldest living Ocean animals is a clam!

A similarly long-lived animal is Ming the clam. Ming was 507 years old, being born during the Ming Dynasty of China (hence the name), or the Tudor period of the UK (it was born in the same decade as Henry VIII). The story of Ming ended quite sadly and unexpectedly, as to measure the age of clams, they must be killed. The scientists doing this experiment hadn’t realised how old Ming was until it was too late, and so in an unfortunate turn of events, Ming had its life cut short.

Ming still gets the title of “the oldest animal with a precisely measured lifespan” though. While this may seem like a long-winded title, the next animal, in the “young” section, will give an idea as to why it’s important.

Greenland sharks and Ming the clam are among the oldest living animals in the Ocean. Posted by Ocean Generation. — *Ming the clam: Radiocarbon , Volume 50 , Issue 3 , 2008 , pp. 399 – 412*

Before we get onto the next animal, we move to the “age of seawater”.

How old is Ocean water?

The “age of water” is essentially a measure of how long water has gone since its last exposure to the atmosphere. This age depends on the speed of Ocean circulation, as faster circulation means younger overall water. The oldest water on Earth can be found in the deep Pacific, currently around 1400 years old.

Looking at our timeline:

Very young things in the Ocean. A timeline by Ocean Generation.

What are the young things in the Ocean?

We now head into the “young” section; the things that date from one thousand to one million years. While it is definitely weird to describe these as young, one million years old is less than 0.1% of the age of the oldest thing on this list.

What’s the oldest animal?

The title of oldest animal goes to the glass sponge (yes, sea sponges are animals). The oldest of these lives up to about 15 kyr (thousand years) old. That’s more than three times as old as the oldest (verified and non-clonal, it gets complicated) tree (about 4,900 years old) ever.

As a quick aside, this tree had a very similar story to Ming the clam, as the scientist who measured its age cut it down to count the rings, as other methods were not working.

The uncertainty on the age of these organisms is large (13 kyr – 40 kyr), due to the measurement method, there is a useful upper constraint on the sponge’s age. We know how sea level has changed in the past, and that the sponge lives at a certain depth below sea level. This means that the sponge cannot have been born below sea level at the time, and so must have been born after the sea level was at its current position.

This pick for oldest animal may be controversial, as some animals are functionally immortal (jellyfish). Despite this, this is a theoretical age limit, which is not what we are looking at. Either way, the oldest animal is in the Ocean.

One of the oldest and largest coral ecosystems

Making a big skip from 15 kyr to 600 kyr, we find ourselves in Australia, in the Great Barrier Reef. While the individual corals aren’t necessarily 600 kyr old, the ecosystem started growing that long ago. For perspective, the oldest human (Homo sapiens) fossil was 300 kyr old.

This means that it’s possible for the Great Barrier Reef to have been around for twice as long as modern humans have been on the planet. It’s uncertain whether this age makes the Great Barrier Reef the oldest living reef in the world, as there isn’t enough literature on reef ages. Despite this, the reef is still significant in age and has definitely been going for a long time.

Our updated timeline:

Young things in the Ocean. Posted by Ocean Generation, leaders in Ocean education.

What is middle-aged in the Ocean?

We finally break a million years, and we’re only into the “Middle-aged” territory.

How old can ice get?

We start off with the oldest ice found on Earth, which is about 5 Myr (millions of years) old. You may think that this ice should have melted, as this ice predates the start of the last glaciation event. However, the way that this ice was preserved was being insulated under sediments and rocks, which kept it cool for long enough to be found in the modern day. Imagine trying to keep a block of ice frozen for a single year, never mind five million. That’s impressive!

How old is the Ocean crust?

Next, we pass through the K-Pg mass extinction (66 Myr ago, read about what happened here), where all the dinosaurs died, into the birth of the oldest Ocean crust, 300 Myr ago. If we’re looking for the “age of the Ocean”, then surely the rocks that hold the Ocean can count in that definition.

The Ocean crust is the supporting basin underneath the Ocean but does not last forever. New crust is constantly being made, while old crust is being removed (called subduction), and so the maximum age of Ocean crust is limited. This oldest crust is thought to have been from a past Ocean that has now closed (yes, regions of the Ocean close up) and is found in the Mediterranean.

Sharks have been around before threes existed. Posted by Ocean Generation.

Ancient fish fossils

Rounding out our middle-aged section, we have the oldest fossil of cartilaginous fish, the group including sharks and rays. A fun fact is that the common ancestors of rays and sharks were around before grass and trees were on land. The fossil has been dated to be about 440 Myr old. While these may not be a part of the definition of “age of the Ocean”, they’re still fun to think about.

Our new timeline:

Middle aged things in the Ocean, a timeline by Ocean Generation.

What are the oldest things in the Ocean?

Now onto the very oldest parts of the Ocean, we look at things that are billions (with a b) of years old.

We have talked a couple of different fossils, but the very oldest of these fossils are found at the Strelley Pool Formation in Australia, dating back to 3.4 Gyr (billions of years) ago. These are fossilised bacteria, which predate even oxygen being on Earth in significant amounts (the Great Oxidation Event, 2.4 Gyr ago). They even had a hand in filling the atmosphere with oxygen! Finding the first fossil evidence of life is a challenge, as early life was made up of bacteria, which are difficult to preserve.

The Strelley Pool fossils are the oldest (largely) undisputed fossil evidence of life. As life is theorised to have started in the Ocean (around hydrothermal vents), perhaps we can say that the “age of the Ocean” is how long life has been in the Ocean for.

Strelley Pool fossils, posted by Ocean Generation. — *Image via doi: 10.7185/geochemlet.1817*

How long has water existed on Earth?

The very last definition of how old the Ocean is, is naturally how long water has existed on Earth as pools of water.

To see this, we can look at some of the oldest rocks on Earth, again from Australia. These rocks from Jack Hills contain minerals which date back 4.4 Gyr ago, which was quite early into the Earth’s lifetime (4.567 Gyr). Looking at the composition of these minerals, it’s possible that these minerals interacted with liquid water upon formation, suggesting the presence of at least liquid water at the time.

This water wouldn’t have been in the shape of the Ocean that we’re familiar with, rather taking a different shape due to plate tectonics. This fact emphasises that we have one Ocean that has been with us for billions of years.

The final timeline:

Old things in the Ocean, a timeline by Ocean Generation.

It should be noted that even though this seems like a complete list, these are only the oldest that we know of in each of their categories. The Ocean is largely unexplored in space (and time, for the cartilaginous fish), and so all ages should be taken with a pinch of salt.

How do we know the ages of things in the Ocean?

A question arises from all of these – how do we know all of these ages? Well, there are many different methods of what we call “dating”, which is measuring the age of something.

Counting growth lines

The simplest, and possibly the most familiar one to you, is counting growth lines. Trees famously grow rings for every year of their life, making counting their age relatively easy. Trees aren’t the only organism that this is useful to, with Ming the clam having a similar dating method.

Ming had annual growth lines that could be found on the inside of its shell (hence the scientists’ need to kill it to measure its age). This helped it be “precisely measured”.

Radiometric dating

With the simple method out of the way, we turn to “radiometric dating”, which uses the behaviour of radioactive atoms to see how old a specimen is. There are several atoms that are useful to us, depending on the timescale that we are working on.

Carbon-14 is an isotope (type of atom) of carbon that is radioactive. This means that the number of carbon-14 atoms decreases over time, with half of the carbon-14 in a sample decaying over 5730 years. We say that carbon-14 has a half-life of 5730 years. This means that we can use it as a clock. Carbon-14 dating is particularly useful for dating life, as all life contains carbon, therefore in some small amounts, carbon-14.

This was particularly helpful when figuring out the age of the Greenland shark, as they have a part of their eye that is formed on birth and does not change afterwards, meaning that from measuring the age of the eye, the age of the shark can be found. This method is also useful in finding the age of seawater, as seawater contains dissolved carbon within it.

A similar method can be done with uranium. The difference between uranium and carbon-14 is that uranium’s half-life is much longer, reaching billions of years. This means that it is useful in dating our very oldest samples. For the Strelley Pool fossils, we know the ages of the rocks around the fossils, and so can infer the age of the fossils, and for the Jack Hills minerals, we can directly find their age with uranium dating.

Dating methods in the Ocean. Posted by Ocean Generation.

Correlative or model-based dating

The last method of dating is “correlative” or model-based dating. For this one, we set up a model, effectively a link between an aspect of a sample and its age and figure out its age from that model.

The Greenland shark age also uses this method of dating. A link between the size and age of the sharks that have had their eye ages measured can be made. This can then be applied to other Greenland sharks. The advantage of this method is that it is much easier to measure the size of a shark than to carbon date its eye age. A model is also used for the glass sponges.

Why is the age of the Ocean important?

While stretching the definition of “age of the Ocean” may be for fun, each individual story in this article is important.

Diving deeper into the oldest members of each category can lead us to many conclusions. Understanding why some animals live longer than others can give us insights into why some creatures live as long as they do.

The age of seawater gives us an idea about Ocean circulation, while Ocean crust tells us about plate tectonics. The big story of the “age of the Ocean” lets us explore the smaller stories important to different aspects of science.

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Elliot Yu

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17. 04. 2026 Elliot Yu

How did the End of the Dinosaurs Affect Marine Life?

How did the end of dinosaurs affect marine life? Explained by Ocean Generation.

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A lot of people know about the meteorite that killed the dinosaurs, but how were marine creatures affected by this event?

66 million years ago, the age of the dinosaurs came to an end, becoming the known as the K-Pg (the geological abbreviation for Cretaceous-Palaeogene) Mass Extinction. A meteorite impact sent the world into darkness, leading to the downfall of the once dominant dinosaurs and many other creatures. Despite the fame of this event, little thought is given to the effects on the past Ocean.

How did the dinosaurs become extinct?

The famous driver for the extinction of the dinosaurs was, of course, the meteorite that struck the Chicxulub Impact Site in Mexico. But this wasn’t the only cause for extinction. The volcanoes of the Deccan Traps in India were violently erupting too, spewing massive amounts of lava. Together, these two events were the drivers for the mass extinction. However, the meteorite and eruptions themselves didn’t directly cause the extinction, instead it was their aftermath. So, what happened?

The world – 66 million years in the past

The world 66 million years ago. — *Map via Atlas of Earth History*

Due to plate tectonics, the world looked slightly different 66 million years ago (Ma) compared to now. Despite the similarities, the world, and so the shape of the Ocean, were different. Firstly, there were more connections between Oceanic bodies, for example from the Atlantic to the Pacific. Next, the Atlantic was much younger and much narrower. Lastly, as there were no ice caps and the climate was warmer, sea level was higher by about 200m.

What is plate tectonics?
The Earth is made up of multiple large sections called “plates”. Plate tectonics is the idea that these plates move around and past each other very slowly. This means that over many millions of years, they can move into completely different arrangements and positions.

What did Ocean life look like before the extinction?

The life found in this Ocean of the past was quite different to the present, but we do see some familiar faces. Sharks, crocodiles and fish still existed, while algal ecosystems (the photosynthesisers of the Ocean) supported the food chain. These weren’t the only things found in the marine world of the Cretaceous period, though.

Cephalopods, which are the group containing modern octopuses and squids, had multiple representatives. Ammonites had been abundant before the extinction, although were on a gradual decline in diversity towards the extinction. These animals had a spiralled shell shape a little like their living cousins, the nautiluses, and lived throughout the Ocean. Alongside them, the nautiluses were also present but made it through the extinction.

Of course, there were also the famous predatory marine reptiles of the time, commonly (incorrectly) included when referring to dinosaurs.

The relatives, the long-necked plesiosaur and the short-necked pliosaur, were two notable groups, the former having a nearly complete fossil discovered by Mary Anning. However, pliosaurs didn’t die in the K-Pg extinction, instead going extinct over 20 million years before (still considered the “late Cretaceous period”, the geological periods are long!).

Instead, the dominant predator at the K-Pg was the mosasaur, which were predatory marine reptiles, like the pliosaur. The difference was that the mosasaurs were better suited to live in the Ocean, as they could adapt better to changes in conditions, becoming more successful and thriving until the extinction.

Mosasaurs and plesiosaurs went extinct. Explained by Ocean Generation

What happened to Ocean life during the Extinction?

As per the name “K-Pg Mass Extinction”, a lot of species went extinct. It’s estimated that around 76% of all species died, being about the same for marine species, from the results of the meteorite and volcanism.

The meteorite and volcanoes weren’t the direct causes; the impact and the lava were nowhere near global scales. Instead, secondary factors caused by the impact and eruptions led to the extinction. The main effect of each was their effect on the food chain, with the death of algae.

The death of algae was a main cause of the marine extinction

When the meteorite hit the Earth, it sent high amounts of dust and debris into the atmosphere, leading to a sort of “curtain”. This curtain of dust blocked out the Sun for a considerable time, leading to an “impact winter” (a period of extreme cold, due to the meteorite blocking the Sun), and darkness. This period of darkness decreased both plant and algae numbers, with both requiring the Sun for energy.

Just as plants are the bottom of the food chain (what we call “primary producers”) on land, algae are the primary producers in the Ocean. The decrease in numbers means that the animals that eat algae would have less food and die, meaning the animals that eat those animals would have less food and die. This knock-on effect up the food chain is one of the main causes of the mass extinction, both on land and in the Ocean.

What happened during the K-Pg extinction? Explained by Ocean Generation.

The volcanoes of the Deccan Traps, along with releasing vast amounts of lava, released considerable amounts of volcanic gases too, notably carbon dioxide and sulfur dioxide. Carbon dioxide, along with being the infamous greenhouse gas, can lead to Ocean acidification and carbon dioxide poisoning. Sulfur dioxide is a potent ingredient in acid rain, also contributing to Ocean acidification.

The reason this is so important is that some algae are dependent on the Ocean being a certain acidity to live. This fast, significant change in acidity led to the death of these algae, having an impact on the marine food chain.

What happened to Ocean life after the extinction?

If all of this happened, why did anything survive at all? A key player in the extinction of animals was starvation. The longer an animal could survive without food, or the more accessible food that an animal had, the more likely it would be to survive.

Mammals and fish: the survivors of the extinction

This applies to both land and the Ocean. Mammals were able to outlive the dinosaurs as they could live off of insects and dead plant matter, paving the way for their domination.

In the Ocean, the major surviving group was the “ray-finned fish”, which make up the vast majority of fish species today. They were able to survive due to some algae thriving shortly after the extinction, leading to the success of these fish.

What happened with marine predators?

For the predators, replacement with fish also occurred. The mosasaurs and plesiosaurs that lived in the Cretaceous period had disappeared, with sharks surviving into the modern day.

The advantage that sharks had on the marine reptiles isn’t well researched, but it could have been to do with the reptiles being warm blooded, hence needing more food than the cold-blooded sharks.

Sharks, crocodiles and fish existed before the K-Pg extinction. Posted by Ocean Generation, leaders in Ocean education.

How did algae survive?

Some algae also had the adaptations required to survive the extinction, with some having an inactive state that they can go into when water conditions aren’t ideal. This means they could live through the cold and lack of light from the impact winter.

Also, reproduction methods likely influenced their survival, as some algae could reproduce by themselves, but others required a partner to reproduce. During times of reduced population numbers, like the extinction, it is more efficient to not require a partner.

Different survival strategies of young cephalopods

Finally, between the ammonites and the nautiluses, they have different survival methods when young. The young nautiluses are birthed in eggs with a yolk to feed from, but young ammonites were thought to have had eaten algae, rather than having a ready food source. Reduced algae decreased the young ammonites’ survival.

Ammonite fossil and nautilus. Posted by Ocean Generation.

How do we know what happened during the extinction?

There is uncertainty about details of the past, because we are 66 million years in the future of the event. This means we must take logical guesses at what happened because we can’t observe events directly. To do this, we look at the rocks and fossils from the past, called the geological and fossil records.

A useful inference we can make is that if a fossil appears in rocks of a certain age, but not in younger rocks, it is likely that the animal has gone extinct. We have applied this to many of the organisms of the K-Pg extinction, like the dinosaurs, which tells us around when they went extinct.

This method is not foolproof though, as this assumption is susceptible to misinterpretations and mistakes. For example, there was a group of fish called the coelacanths that were thought to have gone extinct during the K-Pg, as it hadn’t appeared in the geological record since. However, modern relatives were later found, leading to the realisation that they hadn’t gone extinct, but just happened to not preserve as fossils after the K-Pg extinction.

Why does this matter?

It may seem like studying the past life is just for fun, and while it’s fun, it’s also useful. Understanding the mechanisms and effects of past mass extinctions, especially for the Ocean, can help us prevent a human-made one. Lots of the present-day organisms affected by modern extinction, like whales and corals, live in the Ocean.

Many species could and have disappeared due to human activity, with the current rate of extinction being at least 50 times higher than the background rate (i.e. the rate without human influence). By studying the past, we can understand the effects of our actions and possibly prevent another mass extinction.

The other side of this is that the Ocean is largely unexplored in space, but also in time. Exploring past life can tell us what has once lived on our planet and the environments that they lived in telling us more about our Ocean and Earth.

The current rate of extinction is higher than the rate without human activity.

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Elliot Yu

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15. 04. 2026 Will Steen

Fact file: Fun facts about orca (killer whales)

Orca fact file, posted by Ocean Generation.

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Orca (also known as killer whales) are famous residents of the Ocean. They are fast, fashionable and family-oriented. Frankly, they are fantastic.

Are orcas whales or dolphins?

Orca aren’t whales, they’re dolphins.

The commonly used name, killer whales, can cause confusion. Early sailors became familiar with orca hunting the great whales, naming them “whale killers”. Somewhere in history, that got flipped to become “killer whale”, even though orca are actually dolphins. They are the biggest of the dolphins.

Are all dolphins whales?

Technically, the whole dolphin family, the Delphinoidea, belong to toothed whales – the Odontoceti. Along with the Mysticeti (baleen whales) they make up the cetaceans.

So, you could argue all dolphins (and therefore orca) are in fact whales but they have dolphin-specific traits so, they’re not ‘true whales.’

Orcinus orca is currently a single species, although scientists have suggested dividing it into races, sub species or even different species.

Different groups of orcas are known as ecotypes which inhabit different parts of the Ocean and show physical and cultural differences. They speak different dialects, eat different food and grow to different sizes with different colouration. In many ways they are much like humans.

Order cetaceans explained by Ocean Generation.

Where do orca live?

Populations can be found all over the world, typically preferring coastal seas to the open Ocean, and the higher latitudes closer to the poles. The main population centres for orca are in the Southern Ocean, the north-eastern Atlantic and in the northern Pacific, but orca can be found from Hawaii to the Arctic.

How many orcas are there?

There is an estimated global population of 50,000 orca, including 25,000 in the Southern Ocean, and 10,000 in the waters of Norway, Iceland and the Faroes.

The global population of orca has not been assessed by the International Union for Conservation of Nature (IUCN). We don’t know enough to say whether orca populations are increasing, decreasing or stable.

We do know about the different orca sub populations around the world. Some, such as the Iberian orca population which has been sinking boats, are critically endangered. The West Coast Community of the UK is thought to only have two members remaining: Aquarius and John Coe, who at over 60 years old may well be the oldest male killer whale in the world.

Other orca populations are doing better. Antarctic populations are hard to study, but thought to be stable. Northern Resident orca of the west coast of North America are listed as threatened, but their numbers are increasing by an average of 2% per year after protective measures were introduced for them and their main prey – harbour seals.

Where do orca live: explained by Ocean Generation. — *Image by NOAA*

What do orca eat?

All orca are carnivores but different populations of orca have different preferred diets. Norwegian orca have specialised in herring, northeast Pacific orca hunt salmon and New Zealand orca focus on elasmobranch species such as eagle rays, stingrays and shark species.

Two orca brothers in South African waters, Port and Starboard, are infamous for targeting great white sharks, flipping them onto their backs into a trance-like state known as tonic immobility and eating their livers. As a result, great whites leave the area when orcas are about. Other orcas have been recording other shark species such as whale sharks, seven gill sharks, mako sharks and white sharks.

Nothing is off the menu. Orca will hunt marine mammals, including walrus, dolphins, narwhals, beluga and whales. Orca have been recorded recently hunting the largest animal that has even lived: blue whales.

Being out of the water doesn’t always help. A population in Patagonia will beach themselves to catch the young sea lions learning to swim in the shallows. A population in Antarctica has perfected a technique of swimming together to create waves to break up ice and wash any seals taking refuge on it into the water.

Their most surprising prey? Orca are one of the main predators of moose, who swim between islands and even dive down to eat aquatic foliage.

Nothing is off the menu, apart from humans – no human has ever been killed by a wild orca.

Orcas are also known as killer whales. Posted by Ocean Generation, leaders in Ocean literacy

Killer Facts about Orcas

Orca have been recorded reaching 9.75m in males, and 8.53m in females. The Antarctic Type A ecotype are the largest of all the orcas.
A population off the western coast of North America has revived a fashion fad last seen in the 1980s of swimming around with dead salmon on their heads. Fashion experts compare this to the revival of the bucket hat.
Orca are among the very few species to go through menopause in the wild. Beluga, narwhals, short-finned pilot whales and false killer whales join humans in this exclusive group. This allows orca grandmothers to act as vital sources of knowledge in food location and hunting techniques, while avoiding them competing reproductively with their daughters.
Orca are estimated to eat nearly 800kg a week (roughly 1600 loaves of bread or 8,000 apples).
Orcas only fear one animal – the long-finned pilot whale. They have been observed fleeing at high speed when pilot whales arrive. We don’t know why.
Orca have been known to look after disabled members of the pod.

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Will Steen

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1. 04. 2026 Will Steen

Who are the orca outlaws sinking boats, and why are they?

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Why are orca sinking boats?

Revenge, anti-capitalist revolution, competition, territoriality, a ‘tide-pod’ challenge-esque fad, curiosity – all suggestions to answer one question: why are orca sinking boats?

Much changed in the world in 2020. We all stayed home, made banana bread and, in the UK, attended Joe Wicks workout classes. There was a change in the Ocean in 2020 too: orca began bumping boats.

Now, almost six years on, 8 boats have sunk and over 250 have been damaged. Looking at the data from these interactions, and through knowing these orca, can we piece together why they might have started down this road of vessel vandalism?

What are orca?

Orca (Orcinus orca) are the apex marine predator. Orcas are the largest of all the dolphins (despite their killer whale nickname, they aren’t true whales; read our orca fact file here).

They are found throughout the Ocean, from Antarctica to Norway, Argentina to New Zealand to South Africa.

Orca are highly social and highly intelligent, living in large family groups usually led by a matriarch – an older female. They are capable of advanced communication and coordination, executing intricate, risky and ingenious hunting strategies. Orca are incredible.

They have been recorded hunting whale sharks, white sharks, walrus, and whales (hence their nickname, killer whales). Scientists don’t believe they are particularly affronted by species beginning with W.

When orca hunt, they can create waves to wash seals off ice (or smash the ice they are on) and intentionally strand themselves on beaches to catch sea lions in the shallows. Orca also upend white sharks to paralyse them in tonic immobility (a trance-like paralysis some sharks enter when upside down).

Orcas live in close-knit family groups. Explained by Ocean Generation.

Who are the orca that sink boats?

The Iberian orcas are a small population of orca that reside in the western Atlantic from Gibraltar up to the Bay of Biscay. The ‘small’ is a double entendre. They are among the smallest orca on the planet, with females reaching up to a mere 5.8m and males only 6.5m. They are also small in number: the International Union for Conservation of Nature (IUCN) classify this population as critically endangered, with the population estimated to number only up to 50.

Between 1999 and 2011, 47 individuals from 5 different pods were photo-identified and a further 16 in the Canary Islands, which are genetically distinct (they aren’t family) from the Iberian orca. After accounting for deaths, the Iberian population was 33 in 2012.

In 2023, the number had grown to a relatively stable 37.

Of this orca population, 15 individuals have been identified as boat-bumpers from witness accounts, photos and videos. These sailing saboteurs are then given the moniker “Gladis” – derived from gladiator, or fighter.

The Gladises are in two main pods, each led by an older matriarch. Gladis Lamari is estimated to have been born in 1992 and Gladis Herbille in 1993. Neither of them have directly interacted with boats: they are Gladises as they have been observed close by during boat interactions. They seem content to sit back and watch the younger ones.

What do the Iberian orca eat?

From April to June, the Iberian orcas gather in the shallower waters of the Gulf of Cadiz and the northwestern strait of Gibraltar. Why? Because it is the start of the spawning migration into the Mediterranean of their primary food source: Atlantic bluefin tuna.

In July the orcas shift to the central Strait of Gibraltar as the tuna begin to return to the Atlantic and follow them up the coast of Portugal into September and October.

Iberian orcas feed on Atlantic bluefin tuna. Explained by Ocean Generation.

How do we know the orcas are eating tuna?

By using crossbows, mass spectrometers and following the principle “you are what you eat”. A skin sample was collected from biopsy darts, fired from a modernised version of the ancient weapon. To reiterate: a marine biologist, armed with a crossbow, gets a bit of skin and can work out what the orca are eating.

To assess the diet, the orca skin is analysed for the ratios of carbon and nitrogen isotopes.

Isotopes are atoms of the same element with different masses, due to different numbers of neutrons.

Carbon isotopes indicate where an animal feeds, while nitrogen indicates the trophic level (higher trophic level means higher up the food chain – a predator that eats predators, like orca, have a high trophic level).

In short, the fish an animal eats leave different ‘signatures’ that we can read, telling us what and where our orca are eating.

The Iberian orca showed carbon and nitrogen values reflecting a diet of Atlantic bluefin tuna, with one exception. The female (named Vega) had higher ratios of heavier carbon, showing she was eating more coastal fish species – everyone has their preferences.

Have orca previously sunk boats?

The history between the Iberian orca and humans is a long one. The great Roman author Pliny the Elder reported the presence of orca in AD77. The catch of local fishers was said to increase when the orca were around, and even that fishers would wait for the killer whales to herd the tuna towards shore to help them.

More recently, the tables have turned. Now it is the orca using the fishers for an easier meal, taking tuna caught on fishing lines as they are hauled in. Unfortunately, this is a dangerous strategy, and orca have been seen with deep wounds and amputations, likely from interacting with fisheries.

But before 2020, we have very few instances of orca sinking boats.

In 1820, a whaling vessel, the Essex, was sunk by a sperm whale in the Pacific. In the aftermath, the crew reported orca attempting to sink one of the small boats they had escaped the Essex in.

There were two boat sinkings in the 1970s attributed to orca: in 1972 a 43 ft sailing boat in the Pacific, near the Galapagos, was sunk by a pod of orca. In 1976 another sunk off the coast of Brazil. A juvenile male orca, L98 or Luna, had a long running period of interacting with human things from 2001-2006.

Luna was separated from his pod when he was just 2 years old. He spent five years around Vancouver Island where he would interact with floatplanes and boats, causing damage to the craft and occasionally hurting himself. Sadly, Luna was killed in March 2006 by a tugboat.

How many boats have orca sunk?

Some social media posts have claimed over 1,000 boats, but as of March 2026, 8 vessels have been sunk.

Where have orcas been sinking boats? Explained by Ocean Generation. — *Map via Google Earth*

31 July 2022 – unnamed sailing vessel sinks offshore from Sines, Portugal
1 November 2022 – The Smousse, a 39ft sailing yacht, sunk off Viana do Castelo, Portugal
4 May 2023 – Alboran Champagne, 50ft sailing yacht, sunk off Gibraltar
31 October 2023 – Grazie Mamma, a 46ft sailing yacht, sinks in Strait of Gibraltar
12 May 2024 – Alboran Cognac, a 49ft sailing yacht, sinks in Strait of Gibraltar. From the same charter company as Champagne
26 July 2024 – Bonhomie William, a 39ft sailing yacht, sinks in the Strait of Gibraltar
13 Sept 2025 – Oceanview a 36ft sailing yacht, sinks off Fonte da Talha
10 October 2025 – Ti’fare, a 36ft sailing yacht, sunk off Peniche, Portugal

It is important to underline, everyone sailing on these boats was rescued safely. There have been no injuries or deaths from the orcas, or aggression shown towards humans.

How many boats have orcas interacted with?

Using the last published data from November 2025, there have been 761 interactions between the Gladises (the nickname for orca seen around boats) and boats around the Iberian Peninsula.

The numbers recorded are from the Cruising Association, a sailing group that have encouraged reporting of incidents, which they verify in their network. These numbers are an underestimate, as not every interaction is reported, especially minor ones.

25 May 2020 – the first interaction between two unidentified orcas and a rigid-hulled inflatable boat in the Strait of Gibraltar, no damage recorded.

20 July 2020 – first recorded ‘disruptive’ interaction. Following 9 days saw five more incidents, all south of the cape of Trafalgar, just north of the strait of Gibraltar.

July–November 2020 – 52 interactions, 49 confirmed physical contact. 9 Gladises by the end of the year.

2021 – 146 interactions, number of Gladises rises to 14.

2022 – 138 interactions, 2 sinkings. Number of Gladises rises to 15.

2023 – 186 interactions, 2 sinkings.

2024 – 125 interactions. 2 sinkings.

2025 – 134 interactions up to 10 December. 2 sinkings.

What boats are orcas bumping?

The average length of vessel is 12m, or 39ft. Around 80% of the vessels involved are sailing boats. Of those sailing boats, most have a particular type of rudder– a spade rudder.

What are the theories for orca interacting with boats?

Are orca out for revenge?

A commonly given reason for why orca are sinking boats is that of revenge. The narrative is compelling: an orca, injured by a passing boat, calling her kin to arms to meet the threat of humanity. A response from a beleaguered and besieged marine world.

This theory has largely come about because of an orca named White Gladis.

Who is White Gladis (Blanca)?

White Gladis, translates from her Spanish name, Gladis Blanca. Born in 2005, Blanca is the mother of Gladis Filabres, Gladis Dalila and Gladis Clara. She is herself the daughter of Gladis Lamari, who has been present during interactions but never actively touched a vessel.

As a reminder: Gladis is a simple designation given to any orca involved in nefarious nautical activity. It has its origins in an early name for orca – Orcinus gladiator, meaning whale fighter – and the term gladis means fighter.

The theory is that Blanca had the marks of a propeller and was teaching her kin to destroy the thing that hurt her.

Is White Gladis (Blanca) looking for revenge?

Blanca was certainly one of the early proponents of this behaviour. The first interactions in July 2020 were Blanca, her half-sister Gladis Dalila and an orca from another pod, Gladis Negra.

Orca mothers and grandmothers are key figures in orca society – they are one of the few animals other than humans that are known to go through menopause in the wild, as the grandmothers act as a font of knowledge that they can pass on to the younger generations.

She also does have scars on her skin. But she is an old orca, from a pod known to interact with fishing boats.

Who is White Gladis, also known as Blanca?

Some of those markings are likely to be tooth raking marks, from other orcas running their teeth down her side in play or in mating. Others may be from fishing lines – these orca are known to steal tuna from fishermen, they could well end up with scars from hooks or lines getting tangled.

None of the marks are likely from a propeller – a sticking point for a theory that relies on a negative interaction with a boat.

Is she out for revenge? Orcas are capable of hunting the largest animal to have ever lived (the blue whale) and snacking on the liver of one of the most notorious Ocean predators (the great white shark). They are 5m muscular torpedoes that can develop sophisticated hunting strategies.

If these ‘wolves of the sea’ wanted to wreak havoc upon the sailing community, they could. Only 8 sinkings over 5 and a half years suggests that isn’t the intended outcome.

Are orcas feeling the pressure from humans?

Related to the idea of revenge is the theory of competition between orca and humans. Tuna are the main food of this population and a prized fish for human consumption. Tuna stocks were crashed in the mid 2000s by overfishing, leading to zero Iberian orca calves surviving between 2006-2010.

Orca have been seen with fishing lines attached to them, and one individual in the population, Corsica, suffered a severed right flipper and a cut at the base of her dorsal fin. Corsica was not a Gladis, and although her daughters are given Gladis designation, they have only followed small boats, not sailing boats, and never damaged any. Corsica was sadly found dead in March 2022.

The Straits of Gibraltar is one of the busiest areas of Ocean for marine traffic and has high noise and chemical pollution levels.

The theory is that the ongoing pressures from noisy neighbours that are taking the orcas food is leading them to vent frustration on an easy target – sailing boats. Hard to prove, and the orca with the clearest motivation to do so (Corsica and her relatives) never showed this behaviour.

Are orca using boats as hunting practice?

The behaviour of these orca – ramming and targeting the stern of the boats – is comparable to the hunting strategies they employ when targeting the blue-fin tuna this population eat.

Arguments have been made that the orcas are using sailing vessels as a hunting tool, a training target to show younger orca how to hunt. The incidents started with older females and were followed by younger individuals copying.

The leading theory for our ship shakers? That they want to play.

As previously mentioned, part of the evidence for this is how few boats have sunk – it doesn’t seem to be the intended outcome.

The boats receiving orca attention are interesting. They are mostly sailing boats with spade rudders – these rudders turn completely, as opposed to overshot or hinge rudders, which have a ‘backbone’ of rudder that doesn’t. The boats getting bothered are those with the most mobile pieces on them. Sailing boats typically travel between 5 and 9 knots, a comfortable speed for an orca.

You have slow-moving vessels moving through the orcas home, and they all have a moving thing at the back – pretty enticing for some bored young orca.

The leading theory of why orcas sink boats is play.

The missing orca generation.

The lack of calves between 2006 and 2010 could be in play in a different way here. There is a missing generation of orca: young orca are missing older calves to play with. As any bored child will start doing, they make up some games for themselves, using what is available (boats).

How do you avoid getting sunk by a pod of orca?

The best solution: don’t sail a spade-ruddered monohull sailing vessel around 12m long between Gibraltar and Galicia from July to October.

But seriously: guidance for sailors is unfortunately varied. Initial studies suggested that boats are slightly more likely to be damaged if they keep moving – if boats stop, the orca can lose interest and move off.

More recently, Portuguese authorities maintain that playing dead or reversing is the best way, while Spanish authorities advise motoring to more shallow water.

The International Whaling Commission held a workshop attended by orca experts from around the world. The guidance was to move at least 2-3km from the area of first encounter to an area where rescue, if needed, is easier.

The same workshop strongly recommended against using deterrents that could harm the orcas. Besides the fact this is a critically endangered population, none have been shown to succeed in stopping an interaction and they are likely more dangerous to the people deploying them.

Desperate sailors have used some extreme counter measures to protect their floating homes. Throwing firecrackers and seal bombs; pouring bleach, diesel or chlorine overboard; attaching knives or spikes to the rudder; throwing rocks or heavy chain; electrocution.

It is difficult to condemn sailors reaching for anything they have to hand when a six-tonne animal is apparently dismantling their boat from underneath them. But these measures range from ineffective to cruel, and present as much risk to the sailors as the orca, if not more.

Rather than bombs and chemicals, are there any other potential solutions?

A few genuinely promising suggestions have been put forward. Modifying the design of the rudders to alter the flow of the water could make them less appealing to orcas in the first place. Dropping a barrier of weighted lines around the stern of the boat to prevent easy access to the rudders could give sailors some more peace of mind.

Orca have been shown to flee when they hear the calls of long-finned pilot whales. Sailors could either play pilot whale calls via underwater speakers, learn to mimic these calls or bribe local pilot whales for protection (we would love to see some pilot whale language classes).

Our changing relationship with orcas

Whatever the reasons and whatever the solutions, the situation does give us a chance to appreciate the intelligence and power of one of the Ocean’s top residents.

Our relationship with the orcas of Iberia has been tumultuous. Pliny the Elder wrote about them in AD77, while the birth of Jesus was in living memory. Medieval fishers would welcome them as partners, watching for their dorsal fins to show the tuna were running. More recently, the relationship soured – in 2002, an orca, Burela, was found dead with bullet wounds.

Now it is more confused than ever. The waters are shared by sailors armed with firecrackers, dreading that a black fin will approach from behind, and by whale-watching boats filled with passengers with crossed fingers that they may see the exact same thing.

At the centre of it all, is curiosity. The same thing powering the whale-watching companies could be compelling the orcas. Revenge becomes something more ordinary and wonderful. Just as a younger sibling might poke a sandcastle on a beach and accidentally knock your tower down, the orca could be exploring and playing, with some unfortunate consequences.

Humans and orca have shared the Iberian waters for millennia. We have been wary strangers, reluctant neighbours, collaborative hunters and fierce rivals. How we react to this next chapter in our relationship with them will reflect on us more than it does on them.

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Will Steen

Does the Meg exist? Here’s what scientists actually found.

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31. 03. 2026 Will Steen

Secret life of algae: From oxygen to algae blooms

Secret life of algae. Posted by Ocean Generation

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Every second breath we take comes from the Ocean. More specifically, it comes from algae in the Ocean (thank you, algae).

When the conditions are right, algae flourishes, creating an algal bloom. These blooms can be spectacular, leading to a blossoming of life and a sparkling Ocean, or they can cause serious problems for life in the Ocean and on land.

What do the white cliffs of Dover, the oil fields in the North Sea and Colorado oil shales and the clarifying agents used to make beer and wine have in common? They are all made of algae, a diverse group of incredible organisms which support most of the life in the Ocean.

But you can have too much of a good thing.Large amounts of algae can kill a lot of marine life and be toxic to humans. These events can have huge impacts, as we will see, from modern day Australia to the Bible.

What are algae?

This isn’t as simple an answer as it should be, so bear with us. Unlike mammals or birds or sharks (don’t get us started on “fish”), “algae” doesn’t refer to a single evolutionary group of species.

Instead, the things we call algae are a group of organisms that do the same kind of things, dotted around the tree of life. A group of roughly 50,000 species.

The name comes from the Latin for “seaweed”. The study of algae is called phycology, and algal experts are phycologists, who are still figuring out exactly how they all fit together.

As a good rule of thumb – if it photosynthesises, and it isn’t a land plant, it is algae (we will get to the differences between algae and plants in a minute).

Some of those 50,000 species are very basic organisms such as cyanobacteria, that lack a nucleus and the other advanced bits of cellular equipment that animals have.

Other species are single-celled, floating around in the Ocean. Some are macroalgae like kelp, growing over 50m tall, creating vast forests filled with life and noise (ever wondered what the kelp forest sounds like?).

The magic of algae is something they share with plants. They produce oxygen and grow using sunlight – photosynthesis.

This magic is what nearly all life on our planet is dependent on.

How are algae different from plants?

Fuelled by the sun’s energy, algae filled the Ocean and some conquered the land, becoming the plants that dominate our planet.

Plants evolved from ancient freshwater algae over 440 million years ago. Trees appeared around 400 million years ago. Psst…for context, sharks first appeared around 450 million years ago, so sharks have been around for longer than trees. 1-0 to the sharks.

Plants have developed into some beautiful, complex forms, conquering the land and making up around 82.5% of total biomass (the weight of living things) – humans are only about 0.01%.

Meanwhile, algae have evolved to master the aquatic world.

Physical differences between algae and plants

Plants developed a number of structures as they conquered the land, with roots to hold them in place and specialised structures for capturing sunlight – leaves.

Looking at seaweed there are clear similarities. The “roots” of seaweed are holdfasts, the “stem” is a stipe, and the “leaves” are blades. They look similar, but these structures don’t transport nutrients or gases between each other as the plant equivalents do.

Microscopic algae lack these structures completely.

Differences between plant and algae. Explained by Ocean Generation.

What are the biochemical differences between algae and plants?

We won’t get too technical, but there are some big differences in the biochemistry of the two. Algae are much more varied in their structures, using a wider variety of building materials. Some use silica (glass) and some create chalk. Green algae use a compound called cellulose – the sugar that makes up paper, cotton t-shirts and wood.

Plants, evolving from these algae, adapted cellulose into compounds such as lignin for structural support in their ongoing battle against gravity.

Many algae are named after their eclectic use of photosynthetic pigments.

Red algae use phycoerythrin and phycocyanin (which appear red), brown algae use fucoxanthin giving them a golden-brown colour and green algae use the same chlorophyll a and b as their green, leafy land-based relatives.

The different pigments are utilised to ensure that the algae are most efficiently gathering the sun’s light, which is filtered by the water, modifying the wavelength (and therefore colour) of light that most gets through. More on that another time.

Types of macroalgae, explained by Ocean Generation.

Where can you find algae?

You can find algae everywhere, and each habitat has its own name. They can be found in ice (cryophilic) and hot springs (thermophilic).

Algae are also in soil (edaphic) and in the Ocean (planktonic in the water column and neustonic on the surface). On rocks and in coral (epilithic and endolithic), on fungus and other plants (epiphytic), on turtles and sloths (epizoic) and even inside other organisms (endozoic endosymbiotic) – there is an alga for any location.

Someone should make a song about it.

Why do algae bloom?

When algae grow very fast into large numbers, it’s referred to as a bloom. This can happen at small scales in a pond or at huge scales visible from space. These blooms can be the start of a great flourishing of life, or a deadly threat.

To understand why algae might bloom we need to realise why it wouldn’t and identify what is limiting its growth. Both plants and algae growth are limited by several things: water, temperature, light and nutrients.

We are focusing in on the marine, where water is less of a concern, so short term variation is typically controlled by the rest (although how salty the water is does matter).

Different algal species will have different preferred conditions, but warming the Ocean, with more sunlight and more nutrients, would generally result in more algae.

To refine it further, algal blooms typically refer to large amounts of microscopic algae, kelp forest is technically an algal bloom too, but in headlines, ‘algal bloom’ usually means the small stuff that can produce massive blooms.

Increasing light and temperature

Algal blooms are a normal part of the seasonal Ocean, as light and temperature increase in spring and summer, they allow algae to grow. This growth, like the arrival of spring on land, can be spectacular, as the sea sparkles with bioluminescent algae such as Noctiluca sp. which can give off a blue glow.

What happens in spring that might cause this? The days get longer and the temperature rises. More light and higher temperatures encourage algae to bloom, and they will until one of the other conditions becomes the limit.

Why do algae bloom? Explained by Ocean Generation, leaders in Ocean education

Increased nutrients

When light and temperature are in plentiful supply in the summer months, the growth of marine algae is limited by nutrient levels, especially nitrogen (as opposed to freshwater, where it is phosphorus).

Human activities, primarily the use of fertiliser in agriculture, which is rich in nitrates, have altered the cycling of nitrogen. Some areas of Ocean receive much higher levels of nitrogen from water running off farms, giving the algae all the ingredients they need to thrive and bloom.

Lowered salinity

A lower level of salinity (saltiness in the water) means a higher concentration of water, enabling more growth. An increase in rainfall or ice melting could then lead to an algal bloom.

What makes an algae bloom harmful?

Broadly speaking there are two ways algal blooms can make life a bit rubbish for everything around it – by choking or poisoning them.

Choking blooms

When a large bloom of algae happens, it can disrupt the balance of the ecosystem.

But the real dangers come in the aftermath. As the bloom subsides, it is decomposed by bacteria and other organisms, which use oxygen. This can leave little or no oxygen in the water left for fish and other aquatic residents to breathe.

What makes algal blooms harmful? Posted by Ocean Generation.

Which Bible story might have an algal bloom?

You may not think to go to the Bible for marine science but let us look at the story of Moses and the plagues of Egypt in Exodus 7: 20-21: “…all the waters that were in the river were turned to blood. And the fish that were in the river died; and the river stank, and the Egyptians could not drink the water of the river”. If we assume the bit about blood is descriptive rather than literal, we have a good description of a bloom of red algae.

Following this, we can link some of the other plagues that befell Ancient Egypt. To recap, the ten plagues were: river of blood, frogs, mosquitoes, flies, death of livestock, boils, hail, locusts, darkness and the death of each firstborn son.

If there was an algal bloom that suffocated the Nile, killing many of the fish, then the things the fish ate would benefit, if they could survive low oxygen conditions. Something like a tadpole, which can respond physiologically to low oxygen conditions and thrive. With no fish, you could end up with a lot of tadpoles surviving, and… a plague of frogs.

Another winner would be mosquitos – they lay their eggs on water surface, and the larvae feed on algae. With less predators (the fish are dead) to eat them and a banquet of food, you get a plague of mosquitos.

The death of much of the life of the river could poison the waters, resulting in the deaths of many of the livestock which depend on those waters to drink. The decay attracts flies, meaning one big algae bloom could be exactly the tool a deity would wield to cause five plagues.

Another algal alternative is that the red “blood” came as a result of heavy rainfall in the Ethiopian mountains that are the source of the Nile. The soil there is clay – reddish in colour – and could have suffocated the river by reducing how clear the water is (its turbidity), meaning the opposite of our theory – there were very few algae to produce oxygen for the fish.

In either case, the algae hold the key to the ecosystem, and impacts to algae can have biblical effects.

Toxic blooms

There are three main types of phytoplankton that can make harmful toxic blooms: diatoms, dinoflagellates and cyanobacteria. These produce toxins themselves. When their abundances reach high enough levels, they become toxic to species in the water, and to humans – directly and indirectly.

Shellfish poisoning in the US is caused by algae such as Alexandrium catenella or Karenia brevis (both dinoflagellates) which, when ingested by shellfish such as mussels, can make them deadly to humans.

Shellfish poisoning explained by Ocean Generation.

More directly, blooms of toxic algae threaten life through the water column. K. brevis is amongst the best studied, as it occurs off the coast of the United States in “red tides”. Fish, marine mammals, elasmobranchs, turtles, birds and even coral suffer in waters stocked with high quantities of the toxic algae. K. brevis produces brevetoxin, potent neurotoxins which interfere with normal neural function. It essentially causes nerves to continuously fire, leading to behavioural change, muscular dysfunction and disorientation.

Blue-green algae are another commonly referred to algal bloom. It is named after the colour of the cyanobacteria that causes it, which can produce a wide array of toxins depending on species, none of which are good in high quantities.

Australia saw a harmful algal bloom start in March 2025

In March 2025, South Australia began to feel the effects of a huge algal bloom. As of February 2026, the bloom has impacted 20,000 square kilometres and roughly 30% of Australia’s coastline. Over a million marine animals have died, from over 550 different species. Humans have suffered from eye and skin irritation, coughing and shortness of breath.

The finger was initially pointed at Karenia mikimotoi, a well-known species that often blooms around the world. But after brevetoxins were identified, which K. mikimotoi doesn’t make, researchers took another look using DNA sequencing. This identified K. cristata, which had only been previously found in Newfoundland, Canada in 2014 and in South Africa in 1988.

This is one of the largest and longest harmful blooms recorded, affecting a huge range of marine animals. Leafy sea dragons are one of the state symbols for Southern Australia, but the bloom has hit their populations hard enough that their populations are being reassessed for risk of extinction.

When does an algal bloom become deadly?

The simple answer is when there is too much.

Too much of any one species results in imbalance. Harmful algae blooms come when the balance is lost, for example with an excess of nutrients or an Ocean that is much warmer than usual. Pollution and climate change are increasing the frequency of harmful algal blooms. Not every algal bloom is caused by human activity, but more of them are, and they are more likely to be harmful. Tackling climate change and pollution protect animals like the leafy sea dragon.

Algae facilitated life on our planet, filling the atmosphere with oxygen. Still today, every second breath you take comes from the Ocean, specifically the little algal friends at work. They continue to be the foundation of marine food chains. Algae are amazing; you just don’t want too much.

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Will Steen

Does the Meg exist? Here’s what scientists actually found.

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20. 02. 2026 Will Steen

What is Ocean circulation – and why does it matter?

What is Ocean circulation, and why does it mater? Explained by Ocean Generation

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The Ocean is in constant motion.

Why does Ocean water move? Think about it. What do you need to move the Ocean? What is Ocean circulation, and why does it matter?

There are three drivers of Ocean currents.

The most visible driver of Ocean circulation is the wind. Big storms can whip up the waves, send them crashing into the rocks or barrelling over surfers. Waves can seem like the Ocean is moving a lot, but the water itself is moving mostly in a circular motion. We explain more in our article on the motion of the Ocean.

Prevailing winds can push the waters below in a consistent direction, such as the Gulf Stream, which does drive larger scale circulation. But usually, the wind is only moving the surface, and the Ocean is a lot deeper than the surface.

Next comes the tides. The moon, with a little help from the Sun, shifts the Ocean back and forth, changing sea level by metres in some places. The Bay of Fundy in Canada has the largest tidal range in the world, with almost 12m difference between high and low tide.

However, the tides are always changing. If tides were the only thing responsible for moving the water, then the same water would just be moved in and out. Out in the middle of the Ocean, the water would travel in a big vertical circle, like a giant Ferris wheel. To move the Ocean properly, we need something else.

The third driver of global Oceanic currents is more understated than crashing waves or retreating seas. It takes thousands of years to move water through the deep Ocean, from pole to equator to pole. It’s known as the Ocean Conveyor, or Thermohaline Circulation, and the polar Ocean is a focal point for its activity.

What moves the Ocean? Tides, wind and the thermohaline circulation explained.

Why is Ocean circulation important?

This movement of water is the heartbeat of the Ocean. It carries oxygen-rich waters to the depths, and where it returns to the surface (known as upwelling), the nutrients it brings with it create the richest waters on the planet.

The Ocean is also moving heat and carbon dioxide. It has absorbed approximately 25% of carbon dioxide emissions since the 1960s and over 90% of the excess heat trapped by greenhouse gases has been assimilated into our Ocean.

The Ocean can circulate and ‘drop off’ heat and carbon dioxide in the deep. If the circulation of the Ocean slows, the surface Ocean will get hotter and more acidic. With less circulation, the Ocean’s ability to trap and store two major drivers of climate change suffers.

Global Ocean Conveyor Belt — *IPCC via Smithsonian*

What is Thermohaline Circulation?

Thermohaline circulation is the slow, powerful pump behind Ocean circulation, the main driver of water movement in the Ocean. The name sounds complicated, but it tells us exactly what we are talking about.

Let’s break it down; Thermo-: we are talking about temperature; -haline about salinity, or saltiness. These two characteristics of seawater influence global climate and biological richness.

Temperature and saltiness have influence because they change how dense Ocean water is. Cold water is more dense than warm water, and salty water is more dense than freshwater. If water is denser, it will sink below less dense water.

These simple differences drive a slow, unseen conveyor belt from the poles to the equator and back again. It would take over 1,000 years for one drop of water to complete the whole Ocean circulation.

What will the cold, salty water now disappearing into the depths in the North Atlantic see when it re-surfaces in the Pacific in 3026?

Thermohaline circulation, explained by Ocean Generation.

Why are the Poles important for Ocean circulation?

If the poles are known for one thing, it is that they are cold. So cold in fact, they can chill seawater to the point of freezing (which happens around –1.8 to -2 degrees C / 28.76- 28.4 °F, lower than normal water due to the salt content).

When seawater freezes, it leaves its salt behind. As ice forms, the water left behind gets more salty, which lowers the temperature it will freeze at. More salt = lower freezing temperature. Very salty, very cold water is very dense, and will sink below other seawater.

This downward movement is known as downwelling. Downwelling pushes water along the depths and pulls water across the surface. This is the pump that moves the Ocean.

So begins the Ocean conveyor.

When does cold water become deadly?

Maybe you didn’t think water movement could be exciting. Maybe you haven’t heard of the finger of death.

We know as sea ice forms, it “spits out” salt, creating channels of brine (very salty water), which is colder than freezing. This brine travels down through channels in the ice, collects more salt and cools further.

It reaches the bottom of the ice super salty and super cold. It is so cold it freezes the sea water it touches below the ice, creating beautiful brinicles.

The brine is still too salty to freeze, so travels through the centre of the brinicle, growing it. If this is in a shallow area, the brine could reach the seabed before warming and diluting enough.

This ethereal beauty then becomes a sinister threat. It is so cold it freezes anything it touches. The sea stars, brittle stars, sea cucumbers living below the ice are at the mercy of the finger of death.

Most Ocean movement isn’t as dramatic as the finger of death, but it runs on the same mechanisms.

Finger of death, also known as brinicle — *BBC Earth*

Is Ocean circulation slowing down?

Ocean circulation relies on the cooling and sinking of water at the poles. As the release of greenhouse gases raises the temperature of our planet, especially at our poles, the water is not getting as cold.

We are seeing less sea ice form and the water has more fresh meltwater diluting it. The water is getting less cold, and less salty. Both mean the surface water is less dense, meaning it will sink less. Is the circulation of the Ocean slowing?

One way to study if it is slowing is by looking at how old the water is – older water means slower circulation.

How do you measure how old water is?

At the surface, chemicals and elements are constantly being exchanged between the air and the Ocean. Scientists can look at the chemical composition of the water, looking for indicators for when the water was last in contact with the surface.

Using Carbon-14 as a time marker

Carbon-14 is the usual way, a radioactive isotope of carbon that is used in radiocarbon dating methods from geology to archaeology. It’s also called carbon dating.

How does carbon dating work?

Carbon-14 is an isotope (type of atom) that decays slowly. Half of it will decay every 5700 years or so, known as the half-life.

Measuring the amounts of Carbon-14 can be like reading a timer. Carbon-14 is created naturally when cosmic rays hit our atmosphere, but in much larger amounts by nuclear weapons – levels doubled in the 1950s and 1960s.

This molecular ‘shadow’ has been found in marine animals in the Mariana Trench, showing just how far human impacts reach.

Track the amount of Carbon-14 and you can approximate when it was last in contact with the atmosphere, which gauges age.

Measuring human-made chemicals

Industrial chemicals such as CFC-12 and sulphur hexafluoride are other chemical clues used to age water. Chlorofluorocarbons (CFCs) were widely used in refrigerants and spray cans until they were identified as depleting the ozone layer.

Through global cooperation and effective science, the Montreal Protocol was introduced, preventing the use of CFCs and allowing the ozone layer to recover (learn more about international treaties here). The presence of CFCs can indicate exactly when that water is from.

Using oxygen to estimate water’s age

We can also look at the Apparent Oxygen Utilisation. The principle is that deep water can’t have oxygen added, so the older the water, the more oxygen will be used up from it, meaning older water has less oxygen.

Despite fluctuations caused by other Ocean movers (e.g. the wind), the waters in the deep North Atlantic are getting older, implying the water is not being replenished as quickly, and therefore that the circulation is slowing. The same is happening at the other pole.

The Ocean is made up of many different ‘bodies’ of water, with different characteristics and names. North Atlantic Deep Water is formed in the Arctic by cold, salty water sinking and flowing south. This water travels all the way to the Southern Ocean, where it meets another body of water.

Antarctic Bottom Water is formed at the South Pole and is the coldest and the densest of them all, the real powerhouse of Ocean circulation. But it is warming and there is less of it. The frost-fuelled engine is slowing.

What would a broken Ocean conveyor belt mean? Explained by Ocean Generation

What would a broken Ocean conveyor mean?

The Ocean would suffer.

Deep sea creatures relying on delivery of oxygen and nutrients would be left waiting, as deoxygenated areas grow. The same would happen for surface species that need the upwelling of nutrients from the deep.

If Ocean circulation stopped, there would be dead zones without oxygen in the deep and starved surfaces with no nutrients to support phytoplankton.

It would impact life on land too. If the circulation of the Ocean slows, global climates will shift. Increased storm intensity, more extreme weather patterns and changes to rainfall. Europe could face far cooler temperatures as the tropical water that brings warmth from the equator slows.

That is quite a big if, and fortunately, the Ocean is resilient. New work has shown circulation has slowed in the 2010s and 2020s by less than in the 2000s. This has been attributed to natural variability pushing against the human-caused weakening.

Every reduction in greenhouse gases, every degree of warming prevented, reduces the stress on our Poles and on our Ocean circulation. Keeping our poles cool keeps our Ocean moving.

Keeping our poles cool keeps our Ocean moving. Explained by Ocean Generation.

Post by

Will Steen

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