The Ocean is surprisingly noisy. Sound is used to convey information over long distances, and to neighbours on the reef or in the grass. In water, sound travels farther than either light or chemical cues and moves almost five times as fast as it does in air.
Marine mammals like whales and dolphins are famously loud and use sound to communicate. Sperm whales can reach volumes louder than jet engines. But a shocking truth is that other marine animals contribute to the Ocean soundscape too! For example, did you know that some fish make hums and purrs?
Beyond marine animals, there are other sound sources in the Ocean. Geological sounds (earthquakes and landslides) and our own human activity (engines and drilling) have their own effects on the Ocean soundscape.
What do kelp forests sound like?
Kelp forests are an unfamiliar setting to most of us, so to assist on our adventure of the soundscape, we’ll venture through the woods at the same time.
In the woods, we hear distinctive, familiar noises. The twitter of birds, the chattering of rabbits and the chirps of insects dominate the soundscape. In kelp forests, we can hear the different calls of fishes and the frequent snapping of shrimp.
The noises of kelp forest can be separated by their pitches. Generally, lower tones contain the noises of marine mammals and fish. The higher tones we’d hear contain the clicks of snapping shrimp and the sound of echolocating dolphins (although this is higher than the human ear can hear so it’s silent to us).
These soundscape features often change in both environments over time due to natural factors, like seasonal changes, or human activity.
As the night comes, the sounds of the daytime animals switch to the noise of nocturnal animals.
In the woods, hooting owls and squeaking bats take over the soundscape along with the occasional chirp from foxes. This daily change is seen in kelp forests too, where the activity of animals and therefore the volume of their sounds shifts over the course of the day.
For some species of fish, their noise peaks at sunset and dips at sunrise. As well as this, snapping shrimp are nocturnal, which shows in their activity, as they have peaks at sunset and sunrise but a decreased activity during the day.
Seasonal changes in the kelp forest soundscape
With the arrival of autumn and winter in the woods, some animals migrate or hibernate, removing their noises from the soundscape.
The Plainfin Midshipman fish makes nests near the coast and uses a humming noise to attract a mate. This humming is heard in the kelp forests during late spring and summer, consistent with their mating season. Contrasting this, the presence of snapping shrimps is maintained year-round.
On our walk through the woods, we come across barren spots without trees, caused because of storms or fires. Similarly in the Ocean, an abundance of sea urchins and a lack of suitable food can cause them to feast on kelp clearing the area and leaving a space overrun with small, malnourished sea urchins, with the East Fish camp in California having an urchin density of 26.8 urchins per square metre.
Although urchin barrens may seem like a natural environment, they are created by human activity, just as extreme weather can become more prominent because of global warming.
Normally, sea otters and the occasional fish prey on urchins before the situation gets out of hand. But, due to hunting and overfishing, sea urchin predation is decreased, allowing their population to spike and kelp forests to be removed.
Sea urchin barrens influence the kelp forest soundscape as the region becomes less suitable for some species and more suitable for others. When hundreds of sea urchins move in, they change biodiversity.
A more direct human influence on woodland soundscapes is deforestation. The direct removal of trees by humans to clear space or for resources is easily a big issue, as it decreases habitat space, reducing biodiversity and harming ecosystems.
Listening in our woods, we don’t only hear animal noises but also human noises. Cars on roads which cut through the woods or heavy machinery operating can create loud persistent noises which can disturb the soundscape, affecting the distribution of the animals.
The same is true for animals in the Ocean. Loud noises like drilling and seismic surveys are loud and the noise can be emitted for tens of kilometres, causing confusion and hearing damage in marine mammals and fish.
Other sounds like engine noises from low flying planes and boats can act as background noises which decrease the distance that animals can hear and communicate.
Sound disturbances can normally be mitigated in kelp forests by kelp’s ability to attenuate (absorb and decrease) sound. However, because of the removal of kelp forests, this mitigation can quickly be removed.
The building of docks and other structures may seem like they could bring back attenuation, but they can also transfer noise from cars and docking boats into the Ocean, affecting microenvironments.
What can we do?
It may seem daunting that humans can cause all of this damage, but not all change is bad. Just as forests can be replanted and wildlife protected, as can kelp forests.
The growth of kelp can be stimulated, and areas can become marine protected areas, which can allow areas to be conserved. An example of this is in New Zealand, where an urchin barren has recovered back into a kelp forest within a marine protected area over the period of 20 years.
Looking at how we live our lives, like where our fish comes from or our usage of boats can make a difference in helping this delicate ecosystem.
Is Seaweed the Secret to Ditching Plastic? Explained.
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Plastics play an essential role in modern human civilisation. They are incredibly versatile, providing function in almost all aspects of our lives.
Why plastic is a problem for us and the Ocean?
Fossil-based plastics are infamous for their long-lasting impact on the environment, taking up to hundreds or thousands of years to fully break up. Along the way, they harm wildlife and people both as large plastic items and microplastics.
Plastics have another big problem. They’re sourced from oil, which contributes to their damage to the environment. 3.4% of global emissions were contributed by the plastic lifecycle in 2019, with 90% of that being emissions from production and converting fossil fuels into plastic making materials.
What are microplastics?
Microplastics are plastic particles less than 5mm in size formed from the breakup of plastic. They’re found across the planet, from deep in the Ocean to the snow high in the mountains. They’ve even been found in the human body. We don’t fully know yet what that means for our health, but we do know they harm marine life and can travel up the food chain.
Single use plastics, like plastic bags and straws, are big contributors to plastic waste, making up approximately half of all plastic waste. We only use them once and then throw them out, which means more and more plastic needs to be made to maintain supply.
What is the solution to our plastic usage problem?
Recycling is one solution to this problem, but in 2019, the OECD estimated that only 9% of plastics are recycled.The rest is disposed of in landfill sites (50%), incinerated (19%), or goes unregulated into uncontrolled landfills, fires or the environment, including our Ocean (22%). On top of this, not all plastics are recyclable. Is there another solution?
What are bioplastics?
According to European Bioplastics, “bioplastics” are either bio-based, biodegradable, or both. Bio-based plastics are plastic alternatives which, rather than using fossil fuels to source the plastic, use biological feedstock (materials) like starch or cellulose.
Bio-based plastics are not necessarily biodegradable. Biodegradability has no clear definition or criteria, but in general, a product is biodegradable if a substance can be broken down into water, biomass and gasses. As a result of this definition, biodegradable fossil-based plastics can be considered as bioplastics.
1st generation bioplastics use food crops like corn or soybeans.
2nd generation bioplastics use non-food crops like grass and wood.
3rd generation bioplastics use seaweed and algae.
What’s the major difference between using seaweed and crops?
The major difference between crop-based and seaweed-based bioplastics is where they are planted.
The first two generations of bioplastics use fertile land which could be used for growing other crops.
Seaweed bioplastics are bio-based plastics and derived from seaweed. Seaweed bioplastics don’t have the same problems as the other generations as seaweed grows in the Ocean (which there is much more of than fertile land on Earth), and require only sunlight, atmospheric CO2 and the naturally nutritious waters of the Ocean.
They are a relatively new discovery; the first seaweed bioplastics company was established in 2010. Lady Gaga’s music career began before bioplastics were commercial.
How are seaweed bioplastics made?
The first step is letting the seaweed spores grow before they are put into a seaweed farm. They are then harvested a few months later.
The seaweed contains molecules that can be extracted via chemical processes. These have gelling and film-making (like plastic wrap, not movies) properties which make them useful in bioplastic production.
The extraction process leaves behind residuals. These leftovers can be turned into seaweed pellets which can feed back into the bioplastic making process, reducing waste. They can also be converted into methane which comes with the disadvantage of being a greenhouse gas. However, if captured and stored, it can be a carbon effective source of methane, which can be used in the chemical industry, or as a cleaner fuel than fossil fuels.
Our molecules can be mixed with other substances like nanoclays or silver nanoparticles to improve strength or change properties like making them antimicrobial.
Seaweed bioplastics are already used commercially in places like food packaging – that’s pretty kelp-ful!
What is the environmental impact of seaweed bioplastics?
The life cycle assessment of seaweed bioplastics looks at its carbon footprint from harvesting it from farms in the Ocean to its disposal in bins. Pilot scale assessments (these represent full production at a smaller scale) show that their production released more carbon than plastic, however, models show that scaling up production to full scale makes their carbon output less than plastics.
What are the downsides of seaweed bioplastics?
Making seaweed bioplastics relies heavily on farming and harvesting seaweed. This may present a problem when scaling up seaweed farms, especially to the size of being able to match plastic production, if this is even possible. Seaweed farms take up space in the Ocean, and they affect organisms that are living in areas where farms are viable, like seagrasses and corals by blocking light or choking them.
This problem can be mitigated by moving seaweed farms into the open Ocean and optimising growth by growing two different species in the same space. This can be done by growing buoyant kelp and non-buoyant seaweed next to each other to best use space.
Seaweed can also wash onto the coast from farms and decay, releasing pollutants that were absorbed over the life of the seaweed, affecting the local environment and limiting biodiversity.
There is also the problem that not all bioplastics are biodegradable. While it may be entirely possible that seaweed bioplastics specifically are biodegradable, there isn’t yet enough literature to suggest that this is the case.
On top of this, the definition of biodegradability has no specific time frame in which a material should be broken down in, meaning this vagueness could be taken advantage of.
This reintroduces a problem that we were trying to solve, simply sourcing the plastics from elsewhere.
Which plastic (or alternative) is the best to choose?
There are many factors that go into considering a product: the production, the functionality (how good it is at what it’s supposed to do) and the environmental cost.
However, it can be difficult to remove bias. Take single use paper bags for example. At first glance, they seem much more environmental than single use plastic bags as they’re biodegradable, but when put into practice, they have a higher carbon footprint in production than plastic bags and aren’t as strong. So, it’s difficult to tell which of these is better.
As more research goes into seaweed bioplastics, we may find solutions to the problems associated with them and have a more accurate understanding of their impact as they are produced on a larger scale. For now, it is better to avoid single use items altogether, and to use seaweed bioplastics where available.
What Happened to the Steller’s Sea Cow? Explained.
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There are two theories about what happened to Steller’s sea cow. Let’s unpack them.
Steller’s sea cow was a 7-metre-long, 5-tonne cousin of the manatee; known to graze peacefully in kelp forests. But just 30 years after the sea cow’s discovery – it vanished from the Ocean forever.
In this article we’re going to explore two theories for why this marine species disappeared. Both involve hunting, but one requires an understanding of the habitat that Steller’s sea cow called home: the kelp forest.
By looking at this complicated history, we can begin to understand the complex interactions going on under the Ocean surface, and learn lessons about how we can best preserve these incredible ecosystems in the present.
Steller’s sea cow sketch by Biodiversity Heritage Library
The story of Steller’s sea cow starts with a shipwreck.
On the 6th November 1741, the Svyatoy Petr was shipwrecked on an isolated and uninhabited island, now known as a part of the Commander Islands chain. For several months, the crew of sailors, cartographers, geographers, and natural historians had been carrying out one of the first scientific explorations of the North Pacific.
Stranded for nearly a year, the remaining crew salvaged materials from the wreckage, and built a ship that could cross the Ocean back to Russia.
One of the most consequential outcomes of this failed expedition was the presence of a curious and observant naturalist, George Wilhelm Steller. For almost a year, he made meticulous observations, sketches, and notes on the unfamiliar and captivating wildlife that surrounded him, which have been left to us as an invaluable historical and ecological artefact.
From a massive population to extinct:
One creature left a particularly strong impression on George Steller. He wrote in his journal of ‘gigantic manatees grazing all about the island’s lagoons’. These cousins of the manatee would often exceed 5,000kg in weight. He observed that they were very sociable creatures, sticking in large herds and eating kelp floating at the Ocean surface as though it were grass, ‘in the same way as horses and cattle’.
Although Steller wrote that they were so numerous that ‘that they would suffice to support all the inhabitants of Kamchatka’, a twist of fate left them extinct by the 1760s. To understand them, scientists have had to look at historical evidence and their closest living relatives, dugongs and manatees.
Story One: Hunting
Steller’s crew hunted sea cows as a source of food whilst stranded on Bering Island. Steller recalled a story in his journal about the psychological stress this placed on them. Whilst hunting a female sea cow, a male aggressively followed and tried to ram their boat, following all the way to shore long after the female had died. They also hunted other creatures including otters and seals.
This is the most common theory for the extinction of the sea cow: they were exploited for their meat, fat, and hides, the latter of which would be used in the construction of boats. This theory suggests that the hunting was so widespread and unsustainable that the population was put under great stress and collapsed within 30 years.
Story Two: Loss of Keystone Species
In the past few decades, a group of scientists have put forward an alternative theory.
This theory pays attention to the complex dynamics of kelp forests, and the role that sea otters play as ‘keystone species’: species that play a disproportionate role in managing the ecosystems they call home. As we explained in a recent article, sea otters’ appetite for sea urchins prevents overgrazed ‘urchin barrens’ emerging – desolate stretches of rock with little to no vegetation – in the place of lush and biodiverse kelp forest. Do read this article if you want to learn more!
Urchin barren photo by Ed Bierman, healthy seafloor photo by Zachary Randell
Whilst Steller’s sea cows were hunted on these expeditions, sea otters were the main pursuit. When the first groups returned with the fur pelts of sea otters, traders were so astonished at their thickness and quality that they sold for nearly 100 rubles a pelt – 25 times more than the equivalent pelt from land animals. It’s been said that they were, at some points, worth more than gold! In the wake of the euphoria that ensued, the sea otter population collapsed so quickly and dramatically that they were observed to be at the brink of extinction around the Commander Islands by 1753.
Kelp forests create a complex habitat for a diversity of species, with one study in Norway suggesting that the average piece of kelp in their study site supported 8,000 individual organisms. If sea otters are lost to hunting, the kelp forests can be transformed into urchin barrens, as there are no otters to control sea urchin populations. As kelp is lost, the Steller’s sea cow loses their source of food, a change to their environment that might have ultimately resigned them to extinction.
Sketch of a sea otter by Steller
Which theory about the extinction of Steller’s sea cow is it?
Both theories are reasonable. Ecosystems are complex and difficult to understand completely, and it is probably a bit of both. As I have been reminded by one of the scientists who proposed the second theory, ‘the lack of good data from the extinction of sea cows means that we are unlikely to ever really know.’
Sea cows may be extinct, but this story is not irrelevant, and shouldn’t be the cause of doom and gloom or eco-anxiety.
As scientists have better understood the role of sea otters as a ‘keystone species’ that maintain kelp forests, we have become more capable of putting conservation programmes in place that work. The recovery of sea otter populations in the Pacific is arguably one of the greatest success stories of conservation, bringing back both populations of sea otters and the coastal ecosystems they engineer such as kelp forests. At the moment, we can look to innovative projects such as the Monterey Bay Aquarium’s surrogacy programme for hope, which raises orphaned pups so that they can be reintroduced back to the wild. (You can see them on the aquarium’s live stream here!)
We may have lost Steller’s sea cow, but we can still restore kelp forests for the countless other species that call it home.
Steller had a sense for the value of sea otters, though he may have primarily seen them as creatures to hunt. He even wanted to bring some home as pets. ‘The sea otter,’ he wrote, ‘deserves the greatest respect from us all’. Although he couldn’t have understood the complex work that they do as a ‘keystone species’ as we do today, we can all wholeheartedly agree with him.
But more complicated things are going on below the surface.
As well as capturing our hearts, they are ‘keystone species’: species whose everyday eating, resting, and playing has a disproportionately large role in maintaining the entire ecosystem around them. This article will explore how otters make themselves a home in the kelp forest, and how they’re otterly (sorry!) essential to maintaining one of our Ocean’s most vibrant ecosystems.
Where do sea otters live?
Sea otters (Enhydra lutris) have a range that covers the North Pacific, stretching around a coastline that extends between Japan, Russia, Alaska, and California.
Map: Future Directions in Sea Otter Research and Management
What connects all these places? Offshore – out of sight and below the surface – this whole stretch of coastline is a chain of ‘kelp forests’: magical ecosystems that are teeming with life. Whilst sea otters don’t only live in kelp forests, they are most at home in them as it provides them with food and shelter.
Kelps are a range of brown macroalgae (seaweed, to you and me) that grow up to 50m in length. The brown colour comes from a particular pigment that allows them to capture light below the Ocean’s surface. Like plants on land, they photosynthesise sunlight into organic material, which produces the energy for an entire complex food web around it.
This is the base for an incredibly rich and diverse habitat, and one study in Norway found that the average piece of kelp provides habitat for 8,000 individual organisms, with some even providing habitat for over 80,000!
What do sea otters eat?
If there’s one thing sea otters can do, it’s eat. Studies have estimated that they need to eat between 19% and 39% of their body weight in food to meet their basic needs. To put this in perspective, this would be the equivalent of a person needing to eat about 20 pizzas every day!
As well as sea otters, kelp forests are home to a wide range of other species including fish, seals, and seabirds, and invertebrates such as molluscs, lobsters, and sea urchins. Many of these invertebrate species are found in sea otter diets, but at the top of the menu are sea urchins.
In fact, some sea otters crack open and eat so many purple sea urchins that their bones are dyed a pink to purple colour from the compounds they contain.
Sea otter skull image by Peter Monteforte
How are sea otters ‘keystone species’?
A ‘keystone species’ is a species ‘whose impact on its community or ecosystem is large, and disproportionately large relative to its abundance’. This means that if they are lost from an ecosystem, it can disrupt everything else within it. In the case of the sea otter, losing them can even indirectly lead to the loss of kelp. We have explored a historical case where this happened in an explainer article here.
But how does this happen?
The greatest threat to many kelp forests – especially, but not only, in temperate parts of the Ocean – is overgrazing from sea urchins. When their numbers are left unchecked, sea urchins sweep their way across the seabed, devour all the kelp they come across, and leave nothing but a desolate rocky seafloor known as an ‘urchin barren’.
The varied heights of kelp creates a habitat with different levels that can be compared to the differences between the canopy and floor of forests on land, meaning a diversity of species can call it home. Once an urchin barren forms and kelp is taken out of the ecosystem, the many other species that rely on it for food and shelter can also be lost.
Kelp is a complex habitat that supports a range of small species, which makes it a healthy breeding ground and nursery for fish. This attracts larger species such as seals and seabirds, who suffer knock on effects along with fish when kelp forest is lost.
Urchin barren photo by Ed Bierman, healthy seafloor photo by Zachary Randell
This is where our sea otter’s taste for urchins can come in handy. Sea otters can break through sea urchins’ tough, prickly exterior for food, and do so in such large numbers that they play a crucial role in managing populations. They’re accidental conservationists!
How are sea otters part of conservation efforts?
Sea otter populations had declined very significantly by the 20th century. At the time when much of the initial research was being done on the relationships between sea otters, sea urchins, and kelp, one marine scientist publicly shared his worries that the kelp forests of the Pacific had gone through ‘irreversible degradation’.
Sea otters have a long history of being at the heart of conservation efforts. Hunting them in parts of Alaska and Russia was banned in 1911 in the first ever piece of wildlife conservation policy, and banned throughout the United States in the 1970s.
More recently, sea otter ‘translocations’ – where populations are moved to parts of their former range so they can recolonise it – have reintroduced sea otters to parts of the North Pacific such as Southeast Alaska, British Columbia, Washington, and San Nicolas Island in California. As the relationships between them and the kelp forests they live in has become better understood, reintroducing otters has become more than just about them, but the whole kelp forest ecosystem they can create too.
An exciting project has been taking place over the past few decades at the Monterey Bay Aquarium in California, where orphaned sea otter pups are rescued, rehabilitated, and released back into the wild. Between 2002 and 2016, they reared and reintroduced 37 individuals, with benefits not only for sea otter populations but the integrity of the ecosystem as a whole.
The North Pacific kelp forest: A place to call home
Marine scientists have carried out experiments where they observed the differences between how sea otters behave in parts of the Ocean which have kelp forest in comparison to those places without. As a result, it’s possible to see that the otters themselves benefit from their unwitting conservation work.
Firstly, sea otters love to be around kelp as it is a safe habitat for them. At low tide, kelp sits on the surface of the Ocean, and sea otters wrap up their pups in the strings of kelp so they don’t drift away while they nap or hunt. Their role in clearing the urchin barrens can be really kelpful – restoring the very kelp in which they live!
Secondly, the sea urchins that sea otters catch from urchin barrens are not as nice as the ones in kelp forests. They are small, bad quality, and have poor nutrition. Scientists have estimated that due to the difference in quality, sea otters living outside of kelp forests in the Aleutian Islands in Alaska would need to eat about 1,085 urchins every day to meet their basic needs, compared to just 484 in areas with healthy kelp forests. This means that by restoring kelp ecosystems, sea otters save time and get an extra hour and a half every day to nap or frolic around on the Ocean surface.
Kelp forests can also sustain a more biodiverse and complex food web than urchin barrens. Those otters with a taste for fine foods aren’t stuck with urchins for dinner every day. If you had to eat sea urchins every day, you’d probably be bored and want a change too, right? Kelp forests offer sea otters a more varied diet, from a much larger range of sea creatures including crabs, clams, sea snails, scallops, and mussels.
Just an-otter brick in the wall?
So, how do otters make themselves at home in the kelp forest? The answer is simple: just by being their adorable and authentic selves. If there is one take away from this article, it’s that the health of sea otters are entangled in that of the kelp forest ecosystem they call home.
If you ever find yourself scrolling through cute videos of otters on the internet, just remember, they are not just cute and furry, but truly precious and wonderful engineers of the Ocean’s ecosystems.
How can we clean up plastic pollution in the Ocean?
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Why do beach cleans actually work: Explained.
An army of passionate people take to the beach, litter pickers in hand. Sea spray in their hair and sand under their nails, they comb the beach. Their bags fill with cigarette butts, plastic bottles and crisp wrappers. Spirits are high, notable pieces of rubbish are held up with announcement.
As the sun sets, the beach seems lighter, relieved of the weight of rubbish. The cleaners look over the coast with proud eyes at a job well done.
But as the night draws in, so does the tide. When the sun rises again, it unveils a plastic-laden beach once more. The Ocean has coughed up some of its burdens.
What is the point in beach cleans? Are we rearranging deck chairs on the Titanic or do they actually help combat Ocean pollution?
There aren’t great islands of plastic floating in the Ocean (even the Great Pacific Garbage Patch is a myth). But we are creating a plastic soup. Microplastics fill the Ocean, with some ‘croutons’ of bigger floating plastic.
This plastic can kill wildlife, carry toxins and enter the food chain — all the way up to us.
It’s obvious: we all want less plastic in the Ocean. The question is how to achieve that.
What impact do beach cleans actually have?
A beach clean is more than just a fun day out. They do a whole load of good.
Firstly, they are good for us. Beach cleans (and most coastal activities) have been associated with positive mood and improving our understanding of the Ocean. Combine a beach cleanup with some rock pooling and that’s a brilliant afternoon. Imagine all the things you can find! We feel better cleaning our beaches.
Beach cleans are a chance for people to come together and make a tangible contribution. They act as displays, raising awareness for our pollution problem and encouraging more engagement. A snowball effect.
Beach cleans provide immediate benefit to the natural world too. Removing plastic from the beach takes away its threats straight away, and removes the future threats as well.
Plastic on the beach is exposed to the stresses and strains of the Ocean. Waves breaking, rubbing against the sand and rocks, the sun beating down. All these break up the plastic into smaller micro- and nano-plastics. Removing it before that stage is a lot easier.
Our understanding of the journey of plastic waste is evolving. Recent studies suggest that the vast majority (88% is the quoted figure) of plastic in the Ocean remains floating close to shore. This means our beaches take the brunt of the plastic problem. But that also means it’s accessible: We can remove the majority of the problem with ease and stop it getting worse.
Beach cleans treat the symptoms without addressing the illness.
Beach cleans are not the whole answer. You can’t keep bailing a sinking boat out and expect to float, until you bung the hole. A beach clean treats the symptoms without addressing the illness.
We need more than litter-pickers.
What are the other allies in the battle against Ocean plastic?
The closer to source of plastic pollution we can get, the better. Try filling a glass from someone pouring three stories above you – a lot more water gets spilled compared to just filling from the tap.
Single use plastic bans have shown to be effective in reducing litter. Increasing the responsibility of plastic producers for the end of their products lives would motivate innovation and stop plastic becoming litter at all. A circular economy would prevent the demand for oil to produce more and reduce the amount of plastic that becomes rubbish.
As consumers, we also need to rethink how we use plastic.
How can we change our relationship with plastic?
Moving away from a single-use plastic world is, honestly, going to be tricky. We live in a world where convenience is king. Single-use plastic is very convenient. But there are solutions already working.
Deposit return schemes have proved to be highly effective in increasing the collection rates of plastic bottles. When you buy a drink in a plastic bottle, for example, a small extra fee is paid, which is returned when the bottle is returned. For one scheme, 94% of bottles were returned compared to 47% without a scheme.
Nearly every major manufacturer (98%) now has commitments to reduce plastic packaging. Whether this represents genuine change or sophisticated greenwashing remains to be seen, but consumer pressure and regulatory requirements are making plastic reduction a business imperative rather than a nice-to-have.
The challenge lies in balancing reduction with practicality. Sometimes plastic packaging actually reduces overall environmental impact compared to heavier alternatives – it’s the end-of-life management that needs sorting.
The uncomfortable reality of waste management
Here’s the uncomfortable truth: much of Ocean plastic pollution originates from countries with limited waste management systems. Sub-Saharan Africa, for example, averages 44% waste collection rates compared to 98% in high-income countries. It’s rather difficult to recycle rubbish that’s never collected in the first place.
We can’t simply take Western waste management systems and apply them exactly as they are in other countries. Locally managed, decentralised circular economy models – using local resources and creating local markets for recycled materials – show more promise than imposing one-size-fits-all solutions.
Is making plastic expensive a solution to pollution?
Governments wield powerful economic tools: taxes on single-use plastics, subsidies for recycling infrastructure, and extended producer responsibility schemes that make manufacturers pay for their products’ end-of-life management.
When virgin plastic (new plastic) becomes expensive and alternatives become cheap, behaviour changes remarkably quickly. But it has to be done without disadvantaging those that don’t have access to a cheap alternative.
So, back to the original question: Do beach cleans work?
Yes. But they won’t stop the problem long term. Beach cleans deliver value beyond plastic removal. They’re powerful data collection exercises, providing crucial information about debris types and sources that inform policy decisions.
Beach cleanups are also remarkably effective educational tools – nothing quite drives home the scale of plastic pollution like spending a Saturday morning filling bin bags with bottle caps.
Perhaps most importantly, recent research from Norway found that removing larger plastic items from coastlines led to a 99.5% reduction in microplastics both on land and in water within a year. That’s a genuinely impressive result that suggests beach cleans have more direct environmental impact than critics assumed.
“Removing plastic from the environment before it enters an active degradation phase, into microplastics, will reduce the formation of microplastics in the environment. The decrease of microplastic was over 99% in the water volumes we found on land. When we looked at seawater, the microplastics leaking into the sea was reduced by 99.9%,” – Gunhild Bødtker, senior researcher at Norce
What’s the most effective strategy to deal with plastic pollution?
The most effective strategy combines both approaches: upstream prevention (stopping plastic from becoming waste) and downstream management (dealing with what’s already out there). Think of it as both turning off the tap and mopping up the flood.
Beach cleans work best when they inspire participants to tackle root causes – supporting deposit return schemes, choosing refillable alternatives, and pressuring companies to reduce packaging.
The real measure of a successful beach clean isn’t just the bags of rubbish collected, but the number of people who leave determined to prevent that rubbish from appearing in the first place.
What should you do next to help tackle plastic pollution?
So beach cleans won’t solve the problem. The good news is that effective solutions exist. The challenge is implementation at the scale and speed the problem demands.
Join a beach clean, but don’t stop there. Support businesses with genuine circular economy commitments, lobby for deposit return schemes, and remember that every purchase is a vote for the kind of world you want to live in.
The Ocean doesn’t care about our good intentions. It needs systemic change, and that requires all of us to think beyond the beach. All our jobs can be beach.
Is plastic good or bad? What it means for you and the planet
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A great scholar once said – life in plastic, it’s fantastic. As one of the greatest revolutions in material engineering, plastic has undeniably changed the world.
But were we too successful? Did we end up with a committed friend who is always here for you – but really ALWAYS here, and we can’t get them to leave?
Let’s look at our magic material, where plastic has done good and how we need to change our relationship with it.
What is plastic?
Plastic can mean a lot of things.
We should be careful to define what we mean. Here, plastic is concerning synthetic or semi-synthetic materials composed primarily of polymers, that can mould, press or extrude into different forms. This feature, their plasticity, is key to their importance.
Here’s a table summarising some of the most used plastics. Have a look around, I would guess, from wherever you are, you could see at least five of these.
Textile applications but also in many other sectors
Plastic is everywhere, from our food packaging to our computers, to our furniture. Our clothes, the paint on our walls, the tyres on our car; all have plastic in. So, let’s look at why plastic has become so engrained in our lives.
How does plastic save lives?
Plastic has pioneered a revolution in medicine. Through its versatility, sterility, durability and low cost, plastic has made modern medicine more safe, accessible and effective. Plastic IS fantastic.
Disposable plastic items such as syringes, IV bags and gloves prevent cross-contamination. Plastic has enabled minimally invasive surgeries, reducing recovery time and infection risks.
Plastic prosthetics and implants can be printed or moulded to individual needs. Medical packaging made from plastic keeps drugs and equipment sterile (more on packaging later).
A surgeon or trainee doctor can examine a 3D-printed organ to better understand the patient. Complex procedures can now be done through a single incision using flexible plastic implements. Medical imagery has advanced as machines made from plastic don’t have the interference of metal. Due to the low price of plastic, everyone can benefit from better healthcare.
It’s impossible to know how many lives have been saved by plastic.
How has plastic helped our food systems?
Food waste is a big environmental problem. 19% of food available to consumers is wasted, added to the 13% lost in supply chain.
The UK and Japan are among the only countries to collect consistent food waste data. They have shown reductions of 18% and 31% respectively. Awareness, for consumers, is a powerful driver of behaviour change.
Plastic is a key ally in reducing food waste.
Packaging reduces food waste and increases the shelf life of our food. Plastic packaging does this by stopping the aeration of food and providing thermal insulation.
Think of it this way: if plastic packaging stops your tomatoes going mouldy, you’ve saved all the emissions from growing, transporting, and processing those tomatoes – plus you’ve avoided the methane released when the tomato rots in landfill. The plastic wrapper can be the environmental hero, not the villain.
Take pork as an example. Yes, plastic foam trays create more emissions than butcher paper when they’re made. But only 5% of plastic-wrapped pork goes off, compared to 7-10% wrapped in paper. That means 35% less climate impact overall – the packaging emissions are nothing compared to a whole pig going to waste.
This food preservation revolution has shrunk our world. A mango can now travel from Peru to Manchester and still be perfectly ripe when you bite into it. More food, travelling further, feeding more people – all thanks to a bit of clever plastic.
How is lightweight plastic doing its bit environmentally?
Plastic is light, and strong. It has taken on roles previously performed by much heavier metals.
A car fuel tank, for example, used to be made from steel, much heavier than plastics. A 10% reduction in vehicle weight can result in a 6-8% improvement in fuel economy. Plastics reduce the weight of a vehicle by up to 50%. This results in approximately 14 times lower greenhouse gas emissions than using a steel tank.
In construction, the durability of plastic can be utilised. Due to the lighter weight, PVC pipes have much lower climate impact than concrete (45% less) and ductile iron (35% less). Every truck carrying plastic to the building site uses less fuel carrying PVC pipes. In water pipes, copper is recyclable but loses more heat than a cross-linked polyethylene (PEX) pipe.
How is plastic saving marine life?
There are many examples of plastic replacing consumer demand for natural products; saving marine life.
Tortoiseshell glasses are now made out of plastic, saving the hawksbill turtles who were harvested for their beautiful shells. How many trees are still standing because we have plastic furniture?
Why do we call sponges sponges? Because they were originally the sea sponge, Spongia officialis, that we collected and used as a bath sponge. Replacing the sponges of the sea with plastic ones has alleviated another stress on our Ocean.
Ivory’s another classic case. Before plastic, piano keys, billiard balls, and ornamental trinkets meant elephant tusks. Now, we get the same aesthetic from synthetic alternatives – and elephants get to keep their tusks.
What are the problems with plastic?
Before we get too carried away with plastic’s positive impact on our planet, let’s address the elephant (with tusks) in the room – or rather, the gaps in our argument.
Did plastic actually save those lives?
Medicine improved dramatically alongside plastic adoption, but so did antibiotics, surgical techniques, and our understanding of infection control. We simply don’t know how many lives plastic specifically saved versus other medical advances happening simultaneously.
We’ve built our entire food system around plastic packaging, then use that system to prove plastic’s necessity. It’s flawed logic. Considering the carbon emissions alone is one dimensional – what if we’d spent 70 years perfecting non-plastic preservation methods instead? We’ll never know – but it would be foolish to think plastic is the only solution.
We’ve wrapped modern life around plastic like cling film around a sandwich – so tightly that peeling it away seems impossible.
There are two key problems with plastic:
Plastic has two big issues – its fossil fuel foundations and its longevity. The two mean that plastic can have a two-pronged impact environmentally.
Steel and cement are the only materials we produce more than plastic. Between 1950 and 2017, we are estimated to have produced over 9 billion tonnes of plastic. Half of that total was produced after 2004.
Here’s one of the issues – all the plastic we’ve produced is still around in some form or another. Approximately 7 billion tonnes of it is waste.
Medical masks were a signature of the COVID-19 pandemic. They blocked the spread of the virus, saved lives and helped get us back to normality. But, once used we threw them ‘away’. A back-of-the-napkin calculation estimates that in 2020, 1.56 billion face masks would enter the Ocean. That isn’t a trade-off we (or our friendly neighbourhood Ocean creatures) should have to make.
The vast majority of plastic is made from oil. It has a large carbon footprint, representing around 3.4% of global emissions through their lifecycle. A fossil fuel-free future isn’t plastic wrapped.
Are plastic alternatives the answer?
It isn’t that simple. Some alternatives are more emissions-intensive to produce, so if we maintain a single-use approach there will be greater environmental impact.
The classic example is plastic bags to paper bags. Paper bags are approximately six times heavier than HDPE (plastic) bags, so have three times higher production emissions. Paper requires deforestation and lots of water use. Glass is energy intensive and heavy. There are no easy answers.
Solutions, and their effectiveness, varies by region – in the US, PET bottles have the lowest impact by way of emissions, but in Europe it is aluminium, due to cleaner energy used to produce it and higher recycling rates. This also means the impact of a material can be lessened through wider changes (cleaner energy and higher recycling rates).
Food packaging is an area of growing competition for plastic. Glass, metals and paper are long-standing packaging materials. Natural fibres and biopolymers are other possibilities, but they can be more energy intensive, more expensive and don’t provide the same level of protection for the food.
In medicine, alternatives require more time and energy to achieve the same levels of sterility, and often lack the advantages offered by the lightweight, malleable, cheap plastic.
What is the answer: is plastic good or bad?
Plastic is brilliant and has advanced modern society in a multitude of ways. Unfortunately, there were more skeletons in the closet than we realised. We have more information now than ever before, and more advanced technology is allowing us to come up with solutions to address plastic problems.
There are no silver bullets here. But we need to change our relationship with plastic. One key attitude shift that should definitely change: single-use doesn’t work at large scale. Regardless of material.
How much plastic is in the Ocean? Depends who you ask.
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Plastic is at the heart of Ocean Generation; it is OG’s OG.
Our founder Jo Ruxton MBE produced the award-winning documentary, A Plastic Ocean, and put plastic in the spotlight like never before. But it wasn’t just showing people that plastic was an issue, it was showing that we didn’t really understand the issue.
Nine years on, we’re taking a look at what we know (or don’t) about plastic now.
How much plastic is in the Ocean?
Somewhere between 0.13 million and 23 million tonnes of plastic enters our Ocean each year.
That’s quite a big range. Imagine your satnav saying your journey will take between 12 minutes and 2 weeks. Technically true, but not very helpful.
So, why is this question so complex to answer?
What are the estimates of plastic entering the Ocean?
Zhang et al. (2023): 0.70 million tonnes (95% confidence: 0.13-3.8 million tonnes)
*riverine emissions only † all aquatic environments
And then there’s OECD (2022): they predict that by 2060, 44 million tonnes of plastic will enter the Ocean each year.
That’s a 30-fold difference between lowest and highest estimates.
Why are the plastic in the Ocean numbers so different?
Let’s visualise this better. Instead of trying to calculate the amount of plastic entering the Ocean, imagine that we’re trying to calculate the amount of popcorn falling on cinema floors.
Picture scientists trying to measure how much popcorn hits cinema floors for each film watched. Sounds simple? How would you tackle that?
To compare this with our plastics range, our estimates could be 50kg to 1,500kg of popcorn annually.
Here’s how different research teams tackle the popcorn problem:
The Jambeck Method: Cinema-Goer Profiling Jambeck starts with the approximate number of people that go to the cinema. Then, she would factor in roughly how much popcorn each person would have and the “messy eater” rates, to get an estimate for how much popcorn ends up on the floor.
The Lebreton/Meijer Method: Aisle Monitoring These researchers use data from observation. Actually going to cinema aisles and collecting the popcorn.
They look at how much popcorn a group of people drop during a movie. Then, they predict how much would be dropped by all moviegoers. Meijer took the method further by visiting more cinemas.
The Borrelle Method: Cinema Stocktake This method looks at the number of kernels purchased by cinemas. Using this as a base, they can predict how much gets sold to customers and predict how much will be spilled or dropped during handling and eating.
This gives the amount present in cup holders, the floor of the lobby and hallway, as well as the cinema screen floor, so the numbers will be a bit higher.
The Zhang Method: Simulated Screenings Create a computer model predicting how much popcorn is dropped throughout the cinema. Go and check down the back of specific seats and compare the amount of popcorn found with the amount the model predicted would be there. Adjust and validate the model in line with the findings.
The OECD Method: Future Spill Forecaster It predicts how messy cinemas will be in 2060 based on rising ticket sales and supersized buckets.
What do the studies about assessing how much plastic is in the Ocean do differently?
Each method tackles different bits of the popcorn (plastic) pipeline (the stages where popcorn (plastic) might be spilled on the floor). No wonder their estimates vary wildly.
Bottom-up studies (like Jambeck and Borrelle) start with waste on land and model Ocean inputs. Top-down studies (like Lebreton, Meijer, or Zhang) start with plastic actually observed in seawater and work backwards to estimate how much is entering the Ocean. Like comparing cinema managers’ spillage predictions with cleaners’ floor surveys.
Interestingly, the bottom-up studies predict consistently higher plastic in the Ocean than studies using observed data. To use our analogy again: these studies might be overestimating how messy cinema goers are and so end up predicting too much popcorn on the floor.
Plus, these studies use different years for their data. Jambeck is using data from 2010, while Borelle is using 2016 data. The data at the basis of their work is quite different.
Are we counting all plastic that enters the Ocean?
To show how much we don’t know, a new study (July 2025) has highlighted nano-plastics. Nano-plastics are smaller than 1 µm, which is tiny. It is 1/75th of the width of your hair. Or – if you scaled a metre up to the size of a football pitch, a micrometre would be the width of your hair. Their size means they are very difficult to study.
There has been debate that they can even exist, as it requires a lot of energy to break plastics up to that extent.
This new paper from ten Hietbrink et al (2025) found nano-plastics from PET, PS and PVC (look at this table for the plastic acronyms) everywhere they studied across the north Atlantic.
The amount of nano-plastics they found are comparable to macro and micro-plastic, meaning we are missing a big piece of the plastic puzzle. If this study is accurate, it suggests nano-plastics make up 90% of the plastics in the Ocean by weight, compared to macro- and microplastic estimates. Turns out, our popcorn is shedding a lot of salt on the floor that we haven’t been thinking about.
Interestingly, the paper also highlighted the lack of nano-plastics from PE or PP sources. This could suggest a removal pathway or breakdown process we aren’t aware of yet (which is really interesting). It serves as a reminder that we don’t have the whole picture here. Who knows, maybe there are some ants eating some of the popcorn crumbs?
How much plastic is produced each year?
For context, let’s look at the changes in plastic production over this time:
Year
Estimated Production
Source & Notes
2010
~270 million tonnes
PlasticsEurope (2011 report); includes thermoplastics, polyurethanes, thermosets, adhesives, coatings, sealants, and PP-fibres
2016
~335 million tonnes
PlasticsEurope (2017); reflects continued growth in Asia, especially China.
2024
~460 million tonnes
Based on extrapolation from OECD and UNEP trends; global plastic production is increasing at ~4% annually.
Plastic production has increased by approximately 200 million tonnes over the past 15 years. This we can say with more confidence – we know how much we produce.
What do we know about the amount of plastic in the Ocean?
The Knowns:
Plastic is accumulating in the Ocean
The problem is growing – plastic production has doubled since 2000
Rivers are major transport pathways of plastic
Areas with poor waste management and high consumption of single use plastic have higher leakage to the environment
Fishing gear (as pollution) dominates remote Ocean areas, much land-based plastic remains close to shore
Most plastic never reaches the Ocean
We want to avoid more plastic entering the Ocean
The Unknowns:
Exactly how much plastic enters the Ocean
Exact source breakdowns by region
How much plastic is already out there in the natural environment
Do the unknowns stop the need for action?
What can we do about plastic pollution?
Recent studies are showing that plastic pollution tends to stay in our coastal areas. Currents, winds and tides push plastic back against the coast. Why is this good? Because it makes it easy to clear up! It means that beach cleans are in fact a really useful tool to fight plastic pollution.
Going back to our analogy: When the popcorn stays close to our seat, it’s easy to get it off the floor again. And if everyone picks some up before it gets stamped into popcorn dust, it is much easier.
We don’t know exactly how much plastic is in the Ocean. However…
Science isn’t about having all answers immediately – it’s about getting better answers over time. Does it really matter if 0.13 million or 12 million tonnes of plastic enter the Ocean annually?
The scale of the problem might be debated, but the need to act isn’t. Plastic in any amount is detrimental to the world we inhabit.
While scientists debate over the amount of zeros, solutions remain largely the same: better waste management, smarter materials, improved recycling, reduced single-use plastics, and better fishing gear recovery.
The uncertainty isn’t paralysing – it’s liberating. We don’t need perfect numbers to start fixing the problem. We just need to start.
Each of us can reduce the amount of popcorn on the floor. By consciously buying less plastic you not only reduce plastic waste production but also signal to companies that less plastic is a customer preference.
Picking up plastic from the beach will stop it being broken up by the waves, producing microplastics and nano-plastics, making the problem harder to solve.
The little things matter. The big numbers don’t change the picture.
Finding Nemo introduced millions to the technicolour world of coral reefs.
But beneath its heartwarming tale of family reunion lies a treasure trove of marine biology – some spot-on, some wildly imaginative. Let’s dive in and separate the science from the storytelling. How accurate is Finding Nemo?
Let’s start by identifying some of the main characters.
Who are the fish in Finding Nemo?
The clownfish
Nemo and Marlin are orange clownfish or clown anemonefish (Amphiprion percula), and their home-bound lifestyle is spot-on. Unlike their cartoon counterparts gallivanting across the Ocean, real clownfish are the ultimate homebodies. Adult clownfish rarely venture more than a few metres from their host anemone, making Marlin’s anxiety about Ocean exploration biologically justified rather than neurotic.
What type of fish is Dory?
Dory goes by a lot of names: regal tang, palette surgeonfish, blue tang, royal blue tang, flagtail surgeonfish, regal blue tang to name a few (Paracanthurus hepatus).
Regal tangs like Dory are common throughout the Indo-Pacific, so her presence on the Great Barrier Reef checks out perfectly. However, her famous memory problems contradict everything we know about fish cognition. Studies show that P. hepatus can remember spatial layouts for months and demonstrate complex social learning. More on fish brains later.
How accurate are the fish in Finding Nemo?
Mr Ray the spotted eagle ray (Aetobatus narinari) makes a charismatic teacher, though real eagle rays are typically solitary creatures who’d probably skip group activities in favour of a solo swim.
Gill the Moorish idol (Zanclus cornutus) represents one of the aquarium trade’s biggest challenges. These stunning fish are notoriously difficult to keep alive in captivity due to their specialised diet of sponges and tunicates (a group of marine invertebrates that include sea squirts which look, to non-divers like coloured blobs on the reef). This explains Gill’s dissatisfaction with captivity and desperate escape plans.
The film shows a fish dropping their kids off to Mr Ray’s class using their mouth, representing one of nature’s most devoted parenting strategies.
Cardinalfish (Apogon species) are the most common marine mouthbrooders, with males incubating eggs in their mouths for 8-10 days. This explains why they seem unable to speak clearly – try having a conversation whilst holding 200 delicate eggs in your mouth without swallowing. The cartoon, however, doesn’t look much like a true cardinalfish.
Our current estimates are that green turtles live to approximately 80 years old, so the claim that Crush from Finding Nemo is 150 is a bit steep. Turtles aren’t known to travel in family groups, but Squirt does show the independence of a baby turtle. Right from the egg, turtles are fending for themselves, which Squirt shows they are more than capable of.
Do sea turtles really cruise the East Australian Current?
The East Australian Current (EAC) serves as nature’s highway in Finding Nemo, and this isn’t just Pixar imagination. The EAC is a genuine part of the Oceanic conveyor belt (global network of currents circulating water), flowing southward along Australia’s eastern coast at speeds up to 1.5 metres per second.
Crush’s “express lane” concept isn’t pure fantasy either. Ocean currents do have acceleration zones, particularly near topographical features like seamounts and continental shelf breaks. These current jets can provide genuine fast-track transport for marine life, making the turtle highway a plausible, if simplified, representation of oceanic dynamics.
Green turtles (Chelonia mydas) really do use these currents for epic migrations, though their navigation system is far more sophisticated than simple current-following. The sea turtles use magnetic field detection to create internal GPS systems, imprinting on magnetic signatures as hatchlings and using these for navigation throughout their lives.
Are the vegetarian sharks possible?
Bruce and his gang’s “fish are friends, not food” philosophy in Finding Nemo might seem biologically ridiculous, but nature occasionally surprises us.
Bonnethead sharks (Sphyrna tiburo) can derive up to 62% of their nutrition from seagrass, making them the Ocean’s most successful vegetarian predators. These remarkable sharks have evolved specialised digestive adaptations to break down plant cellulose – essentially becoming underwater cows with teeth.
Whilst no shark is completely vegetarian (they still eat crabs, especially when they are older), the bonnethead’s plant-munching abilities suggest that Pixar’s gentle giants aren’t entirely impossible – just highly evolved.
Bonnethead sharks photo by Robin Riggs
Other creature features in Finding Nemo
Pixar’s attention to detail shines with creatures like the Spanish dancer (Hexabranchus sanguineus) – a spectacular sea slug that really does inhabit the Great Barrier Reef and can reach 40cm in length. These crimson beauties are nature’s underwater flamenco performers, funky reef rugs on a magic carpet ride over the corals.
However, some characters are biogeographical impossibilities. They wouldn’t be in the same scenes.
The anglerfish is most likely a black sea devil (Melanocetus johnsonii), the same species filmed swimming to the surface in early 2025. Whilst visually terrifying, the encounter represents a fundamental ecological error. These deep-sea specialists live 200-2,000 metres (656 – 6561ft) down, where they’d never encounter shallow reef fish. Our clownfish friends don’t usually stray below 15m (49,2 ft). The poor blobfish is a good example of what happens when you take an animal out of the pressure range it’s adapted to.
Similarly, Nemo’s classmate Pearl is a flapjack octopus (Opisthoteuthis californiana). These are usually hanging out at depths of 200-1,500 metres (656 – 4,921 ft). These adorable cephalopods (who had a new species found in 2025) are built for life under crushing pressure and would be about as comfortable in shallow reef waters as a penguin in the Sahara.
Let’s really get stuck in. Pearl talks about one of their arms (they say tentacles, but we know octopus have arms) being shorter than the rest. This means two things – that Pearl is a male octopus, and that arm is their hectocotylus, or an arm shorter than the rest that’s specialised to store and transfer sperm during mating.
Finding Nemo got it wrong? Let’s talk clownfish reproduction and genders.
Since we are ruining childhoods, let’s address the elephant seal in the room. Brace yourself for the biological bombshell that completely rewrites Nemo’s story.
Clownfish live together in anemones, with the largest individual as the matriarchal female. The largest male mates with her, with other smaller males helping with the chores and waiting their turn.
When Coral, Nemo’s mum, died in that barracuda attack, the real biological story would be different. Within 10-18 days, Marlin would undergo a complete sex change, transforming into Marlina – the new dominant female clownfish of the anemone. This isn’t just changing wardrobes; it’s a full hormonal makeover involving suppressed testosterone and elevated oestrogen.
But would Marlina then mate with Nemo, as some marine biologists suggest? (Because Nemo was the only clownfish in the anemone.) Probably not. Studies show that clownfish larvae typically disperse 7-12 kilometres from their birth sites, and genetics prove most anemone families aren’t actually related. Marlina would more likely wait for a wandering young male to join the family and restart the dynasty properly. Thank goodness.
Does Mr Ray actually teach anything?
We love that Mr Ray’s impromptu biology lessons contain genuine scientific gems, though we do have notes. His Ocean zone definitions are accurate – the mesopelagic (200-1,000m or 656 – 3,280ft), bathypelagic (1,000-4,000m or 3,280 – 13,123ft), and abyssopelagic (4000m+ or 13,123ft+) zones represent real oceanographic divisions with distinct communities.
His species song (it’s called ‘Let’s name the species’, if you want to look it up) is catchy and gives a fun overview of the species you can find on a coral reef.
“Cnidaria” would be more accurate than “coelentera”. Coelentera is an old term grouping a lot of the animals he goes on to name: hydrozoa (hydriods like the Portuguese man-o’-war), scyphozoa (true jellyfish), anthozoa (coral and anemones) and ctenophora (comb jellies). Add in the porifera (sponges), byrozoa (colonies of moss animals), echinoderma (urchins and sea stars) and “some fish like you and me” and you have a pretty comprehensive overview of life of the reef.
Mr Ray’s excitement about “stromalitic cyanobacteria” is understandable and surprisingly sophisticated for a children’s film. These layered rock formations, created by ancient cyanobacteria, represent some of Earth’s earliest life. They were crucial in the Great Oxygenation Event 2.4 billion years ago. We can thank them for introducing oxygen to the atmosphere! Even now, the Ocean provides around half the oxygen we breathe.
Cleaner wrasses (Labroides dimidiatus) pass the mirror test – a cognitive benchmark previously thought exclusive to mammals and birds. Meanwhile, archerfish demonstrate remarkable learning abilities, accurately spitting water at insects with ballistic precision that would make a sniper jealous.
(additional note – read What A Fish Knows By Jonathan Balcombe for more)
Scientific pet peeves in Finding Nemo
The blue whale
The film shows Marlin and Dory falling to the back of the throat, to be blown out of the blowhole into Sydney harbour. But blue whales can’t blow something out of its blowhole from its mouth.
A whale’s blowhole is linked to the lungs, nothing else. It isn’t spurting water out, it’s a mix of mucus and water on its skin (think blowing your nose when you’re wet). Scientists can actually find out a lot from a whale from its snot, and they use ‘SnotBots’ – drones to collect whale blowhole bits.
The jellyfish
The jellyfish in Finding Nemo aren’t really any specific jellyfish, just mash of a few features to create a generic jelly. The closest real-life versions are the maeve stinger (Pelagia noctiluca) or the Amakusa Jelly (Sanderia malayensis), but neither are a perfect fit.
Despite the sound effects, they don’t electrocute their prey – they have small cells firing tiny needles loaded with venom into anything that touches them.
Marlin claims “I am used to it”. There isn’t much science to say that would help. Remember Nemo brushing in the anemone before school? That is science! Clownfish avoid being stung as they have a protective mucus layer similar to the anemone (it has to avoid stinging itself). They brush up against the anemone to coat themselves in the mucus, keeping them safe from stings. But this is specific to their home anemone and wouldn’t help much against a smack of generic jellyfish. Marlin isn’t any more jellyfish-proof than any other reef resident.
So, is Finding Nemo accurate?
Finding Nemo succeeds brilliantly in capturing the wonder of marine life whilst taking considerable liberties with biological reality. Its greatest accuracy lies in depicting clownfish territorial behaviour and anemone relationships, whilst its most glaring errors involve biogeographical impossibilities that would make any marine biologist wince.
We can’t not mention how clownfish would actually react in Marlin’s situation – a biological reality that completely transforms the story’s foundation. It’s a perfect example of how nature’s truth can be stranger and more complex than fiction.
Perhaps the real magic lies not in perfect scientific accuracy, but in inspiring curiosity about the Ocean’s genuine wonders. After all, reality is often far more extraordinary than anything Pixar could animate.
Can we rebuild coral reefs? The promising (and weird) world of coral reef restoration
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Here’s what you need to know about coral reef restoration:
Corals are cool. But the reefs face danger. A warming Ocean causes corals to bleach more regularly. Some estimates say we have already lost 50% of the world’s coral reefs.
While we work to reduce the emissions of greenhouse gases, to keep our world from warming, we can also look to support the recovery and rebuilding of impacted coral reef systems. So today we ask: how can we restore our coral reefs (and how is a coral reef like a struggling orchestra)?
Why should we care about coral reefs?
Anyone that has had the privilege of diving on a coral reef will tell you how special these places are.
Reefs cover less than 0.1% of our Ocean floor but support 20-30% of marine species. We have tried to estimate the economic value coral reefs bring, but it’s a difficult area, and economists can’t agree on the price tag.
The range of $30 billion to over $300 billion puts coral reef value somewhere between “tremendously valuable” to “astronomically precious”. Include the goods and services provided by coral reefs and the estimated figure is $2.7 trillion. Trillion with a T.
Coral reefs are excellent shields – healthy reefs can absorb 97% of wave energy. This protects our coasts, on which many of us live. Think of the most famous reef in the world – the Great (what?) Reef for example.
So, we have to keep our corals around. The question is: how are we going to? Let’s take a look at the three most common coral reef restoration methods.
Image credits: Coral gardening photo by the BBC, Microfragmentation photo by Blue Corner Dive
Fragments of healthy coral are taken from an existing coral reef and placed in a nursery. This nursery is set up for the baby coral to thrive. When the corals reach a big enough size, they are ‘planted’ back onto the reef.
This is a very accessible, increasingly cheap way of tackling coral decline. Costs are estimated to drop from $150-$400 per coral to <$10 per coral with improving techniques. It doesn’t require expensive equipment, and is a very visible, practical way to engage communities.
Does coral gardening work long-term?
Not sure. Short-term results? Pretty promising. Two large projects (Coral Reef Foundation in Florida and CARMABI in Curaçao) claim over 80% survival after one and three years respectively.
However, it isn’t all sunshine and coral roses. These figures aren’t peer-reviewed (cross-examined by other scientists) and likely reflect best-case scenarios for certain coral species.
Gardening projects, however, tend to focus on fast-growing genus like Acropora, ignoring slower growing (but just as important) species. This results in ‘restored’ reefs that are low in biodiversity.
It’s like trying to have an orchestra with only violins. It is technically music, and possible to even be good, but lacks the depth and the magic of the interplay between instruments that brings it to life.
(One of our marine scientists favourite orchestral pieces is the Planet Earth II Suite: the layering of the song as different instruments come in make your soul soar. What other piece can boast having sleigh bells?? Listen here.)
This coral restoration method is also limited in scalability – can it be used to make a big difference?
Coral gardening is like trying to replant the Amazon by using window boxes. It’s cost effective, and great for fast-growing corals. BUT it produces reefs with low genetic diversity (making them vulnerable to disease) and low species diversity.
Gardening alone isn’t going to save our coral reefs.
Can cutting corals into tiny bits help?
Microfragmentation is chopping up coral colonies into little pieces. The fragments are placed next to each other, and will grow out, to form larger colonies.
The key advantage here is in the species this method targets, such as star or brain coral.
Where, with coral gardening, we are predominantly working with fast-growing corals, this is for the slow-growing corals that are key to reef building, and for whom other methods won’t be effective. These are the bass section in our orchestra: there are less of them, and they are slower, but still crucial to the symphony.
Studies have suggested that this method of coral restoration can accelerate the growth of massive colonies by 10-15%.
However, this is limited to massive species and carries the same dangers of limited genetic diversity as gardening, if few donor colonies are used.
As coral reproduction is strongly linked to size, smashing colonies into little bits certainly impacts their reproductive capacity in the short term. Currently, we don’t know how much or how long that effect lasts.
While this method is an excellent boost for the big boys on the reef, it’s not a reef-wide solution. If it’s used with more conventional gardening, you can help specific species of corals grow more successfully. But how can we support the entire reef system, in all its complexity and diversity?
How do corals reproduce?
Coral reproduction is weird. A few nights of the year, all the corals on the reef will release their eggs and sperm to mix in the Ocean currents. These are called coral spawning events.
The fertilised eggs will be Ocean floaters until they find a spot to settle. Most species settle within two weeks, but some can take as long as to 2 months.
Can we increase the amount of coral larvae settling?
There’s growing appreciation of the different ways coral larvae decides where to settle. We now know that the sounds produced by a healthy reef act as a draw for young corals (find out more about the sounds of a coral reef here). Similarly, we are now realising that young corals “smell” their way to their new home.
These solutions increase coral settlement, helping the reef rebuild itself. This is like advertising for more players in the orchestra, looking to bring in new talent. But what if we take that further?
So, how can we help the corals? By collecting the eggs and sperm during spawning events and taking them back to the lab. There, they have the best chance at fertilisation, and the larvae can be reared until they are ready to settle. Then, they can be released back to the reef.
We can protect the coral at their most vulnerable stage of life.
In the wild, less than 1% of coral larvae will make it to settlement. Of those that do, up to 90% won’t survive the first few months. The proportion of larvae to survive to a juvenile coral is minute, somewhere between 0.001 – 0.1%.
Through assisted reproduction, the success rates are still low, but much higher than the wild. Some studies have shown survival rates to a year to be 0.1-1%. That might seem small, but it’s at least ten times better than the chances for a wild coral larvae. Others show an increase in coral cover after nearly three years. Even more promising? Drop the young corals in, rather than manually fixing them to the reef (a seeding approach), survival rates after a year can reach a whopping 9.6% while the costs remain low.
Here’s the real magic: these methods keep the gene pool diverse and interesting.
We’ve already discussed fragment-growing methods like coral gardening and micro-fragmentation. But unlike fragment growing (which is basically coral cloning), assisted reproduction gives us reefs with genetic variety – think coral cousins rather than identical twins. And that variety? It makes reefs more resilient long term.
This would be the equivalent of sponsoring a musical training programme, nurturing the next generation to guarantee the success of our orchestra.
Where’s the catch?
All the data here comes from projects with scientists doting on every need of the corals. Basically: If we were to strip back the money and the monitoring, the survival rates of corals will probably take a hit.
Assisted reproduction works with the natural reefs, which is its strength as it maintains diversity and avoids the risks of disrupting the ecosystem with new species. It’s also a weakness, as some reefs have lost too many sexually mature corals to rebuild themselves.
While it may not be the most efficient way to resurrect a reef, assisted reproduction could make the difference on degraded reefs needing a boost.
Are artificial reefs the answer?
Like corals, people are great builders. Like us, corals need a good foundation to build on. Some of the most fun coral reef projects focus around providing those foundations, through concrete blocks and 3D printed units.
These foundations can encourage our polyp pals (AKA: coral babies) to settle down and make their home. We can build a new concert hall for our orchestra.
Plus, it works quickly and can be scaled up easily. Like coral gardening, artificial reef building is accessible enough for local communities to get their hands wet. And there’s nothing like a concrete reef structure to make conservation visible *literally* and raise the profile of reef protection efforts.
But we don’t have a silver bullet here. There is concern that they could act as an ‘ecological trap’. They are fish magnets, not factories – they concentrate, not create.
Natural reefs and their residents settle and thrive not just because of a hard surface, but because there are good water conditions, plenty of food for their inhabitants and their populations are balanced.
A reef in a poor location could end up negatively impacting the local fish. Imagine a new housing estate, but with no water and no shops. And acid rain. And bears. This is not a good housing estate.
For artificial coral reefs to work they must be designed AND located with care and understanding. Don’t build a concert hall with terrible acoustics, no electricity and no public transport links. You need to know the area you are building in.
Can we make super corals to survive climate change?
None of the approaches so far tackle the root issue. The main threat to coral reefs is that the Ocean is changing faster than they can cope with.
Could the answer then lie in us accelerating their adaption, selecting the more heat-resistant corals as evolution does, but faster?
Our orchestra can experiment with new instruments and compositions to make a new sound.
What is a super coral?
Through selective breeding (choosing corals that can take the heat and breeding them) and microbial manipulation (like giving corals a probiotic yogurt, with beneficial bacteria and other tiny friends), we may be able to create ‘super corals’.
But temperature isn’t the only thing at work. These super corals have shown decreased resistance to Ocean acidification, the co-conspirator to Ocean warming. Think of a triathlete that can swim *like a fish* but also cycles like one. One-trick ponies aren’t what we’re going for when it comes to building healthy coral reefs.
Another simple hesitation is the amount we don’t know. How could the super corals fit in? Will they outcompete naturally evolving corals? Disrupt ecological balances we don’t yet understand? Will our new music find an audience?
Despite these challenges, assisted evolution remains a promising way for reef conservation in a rapidly warming world.
As one researcher memorably put it: “We’re not playing God with corals; we’re simply giving evolution a helping hand when we’ve rather inconsiderately moved the finish line.”
But if we are making new music, maybe we need a different orchestra set up.
Is coral reef restoration the way to go to save reefs?
New approaches and ways of thinking suggest that we should embrace our changing world.
We may not be able to ‘restore’ our reefs to the way they were, as our world is not the same as it was. Instead of spending time, money, and effort trying to build the reefs that used to exist, we could help build a reef that can thrive in the future conditions of the Ocean.
To play to the tune of the future, maybe we need more woodwind and brass. Think more jazz improvisation than classical recital.
This could offer a more pragmatic approach, acknowledging that full restoration is not feasible in the long term. It focuses on ecosystem function rather than maintaining the old reefs and could integrate the use of ‘super corals’.
But this comes with the issues of the unknown.
Ecosystems are notorious for their chain reactions. Tweak one thing, and something you thought completely unrelated is affected. Bring wolves back to Yellowstone? Suddenly the rivers change course. Remove tiger sharks from an area? Watch the dugongs reduce the seagrass to mud flats since they don’t have to watch their backs.
How would the new ecosystem function and effect the life around it? What if the new saxophonist doesn’t get on well with the trombone players? What if the audience don’t like it?
So how are we doing with coral reef restoration?
One estimate calculates that less than 0.1% of degraded reef area is under active restoration. Most projects are small-scale (100m2 or less) and short-term, with monitoring lasting less than 18 months.
But reef restoration is a stark reminder – humanity can act.
Coral bleaching is among the most visual representations of our changing climate. But the time, effort and care that is devoted to restoring coral reefs around the world shows the desire to protect our natural world.
For us to have healthy coral reefs, to have our orchestra really sing, we need to combine approaches. We can’t focus only on strings or on bringing in the young talent. We need to support the whole orchestra so we can enjoy the music.
As corals have been a poster child for the degradation of our world, so too could they be the success story. Every young coral nurtured today could be the foundation of a healthy future reef, different to yesterday’s maybe, but no less important for our blue planet.
Why is the sound of coral reefs important? Explained.
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Take a deep breath. Immerse yourself. Imagine diving onto a coral reef. Multicoloured arms reach up from the seabed, fish fly by on their busy way, shrimps clean their clients, anemones wave in the water.
Energy and movement surround these bustling underwater cities. Let us explore the sounds of coral reefs (and let’s see how many synonyms for noise we can get in).
Had we asked you to put yourself in the jungle, or on a busy city street, you would have probably filled your ears with the calls of unseen birds and insects, or the honking of a taxi and chatter of fellow bipeds. The sounds of bustling coral reefs are just as diverse and entrancing.
What sounds can you hear on a coral reef?
Whistles, pops and hums. This background noise often stays as exactly that: background, largely unnoticed. Yet through advancements in bioacoustic research, we have begun to dissect the noises coral reefs make and realise their importance.
Video by Will Steen
If you take deliberate notice you will begin to hear the background crackle produced by the sharp pops of pistol shrimp. Pistol shrimp produce sounds exceeding 200 decibels at the source – a conversation is around 60 dB, city traffic 85dB and a jet engine 30m (100ft) away is approximately 150dB. Using their specially modified claws, they rip the water apart, creating cavitation bubbles that briefly reach temperatures comparable to the sun’s surface (up to 4,700°C).
Then you hear the grunts of clownfish families talking to each other in their anemones. Gradually the other croaks, growls and even fish blowing raspberries come to your attention, and where there was only white noise is now a rich tapestry of sound. Coral reefs are bursting with sound and life. In fact, reefs support over a quarter of all marine life.
Pistol shrimp: Arthur Anker/Flickr
Why is sound so important for coral reefs?
The coral reef soundscape is crucial not only for the individuals communicating with each other, but for the survival of the reef itself.
Residents of coral reefs use sound in different ways. The Ambon damselfish can be heard singing to attract a mate; saddleback clownfish grunt to other members of their colony, warning of potential predators. And predators use sound to co-ordinate their hunts.
We now understand that young animals will listen out from the open sea and select their future home by listening to it.
This means that the health and resilience of coral reefs depends (at least in part) on their residents’ din. Recently, even coral larvae have been shown to move towards the sounds of a healthy reef, called home by the hubbub.
There are some new faces on the coral reef: us. Say what you will about people, but we are rarely subtle.
Our visitations to the marine world bring our own katzenjammer. Motorboats busy themselves buzzing around, whilst seismic surveyors searching for oil and gas fill the water with explosions, and construction work hammers the seabed with steel piledrivers.
Most of the noise on coral reefs comes from our boats – engines chugging and rattling, propellers producing bubbles through cavitation just as the pistol shrimp do – these bubbles bursting with a screech. We create an ‘acoustic fog’ – as described by bioacoustic researcher, Steve Simpson.
We are realising with more clarity the effect of our racket. When motorboat noise is present, fish are more vulnerable to predation, perhaps due to warning calls being drowned out, or confusion slowing reaction times.
Fish show signs of stress and stop their usual activities, including parents fanning their eggs with oxygen-rich water. This can mean young fish don’t develop properly and less of them will survive.
As healthy reefs are noisy, the opposite is also true: damaged or dying reefs lose their song.
As our fog of noise descends and reefs quieten under the stresses created by us, young crabs, coral and fish listening as they drift in the Ocean can’t hear their homes call to them. Less offspring to fill these underwater cities puts their future in further doubt.
What can we do to protect coral reef soundscapes?
But hope isn’t lost! Whenever we give it a chance, nature exceeds our expectations to recover.
The growing research in bioacoustics is pushing our understanding of the noisy world under the waves. As we learn more about our Ocean’s audio, the desire and ability to protect it grows too.
“Sound is a pollutant we have the most control over, and we can really fix things” – Prof Steve Simpson
Ongoing research is decreasing the noise of our engines, and protection of our marine areas is growing. We now know minimising our audio footprint will improve feeding and mating behaviours of the animals on the reef, allow parents to feed and nurture their young better, and give fish a better chance to avoid predators.
We can now listen to a reef and learn how healthy it is. Phonic richness – the diversity of animal produced sounds – is greater on a healthy reef.
Early experiments with acoustic enrichment show promise. When speakers play healthy reef sounds, they attract significantly more juvenile fish and some invertebrates than areas where no sound was played.
While still experimental, this approach could potentially become one tool in the coral reef restoration toolkit. Read more about the other approaches to reef restoration here.
Our Ocean is resilient and, as we deepen our understanding of it, we can more effectively protect it.
Dunk your head again onto your imaginary coral reef, take a deep breath. Close your eyes. Just listen to the Ocean sing.
White branches reaching out, stark against the blue. Where there was colour, now only ghostly white. This haunting transformation isn’t just a visual tragedy – it’s the silent SOS of some our Ocean’s most spectacular ecosystems. This is coral bleaching.
Coral reefs aren’t just beautiful — they’re nurseries for fish, protect coasts from storms, and feed millions of people. When coral reefs bleach, their whole ecosystem is at risk. But what is coral bleaching? What causes it, and why does it damage reefs?
Are corals animals, plants or rocks?
Corals are animals. Some may have stone skeletons and live with plants. But all corals are animals.
Corals are tiny animals called polyps. Each polyp has a soft body and a mouth surrounded by tentacles, like a little sea anemone or an upside-down jellyfish. All these animals are related – they are cnidarians (silent c), named after their cnidocytes – special cells that can sting.
Where does coral’s colour come from?
Corals are incredible animals. They build immense structures that provide homes for marine species, protect the coast and create oases in the ‘desert’ of tropical seas (there are very few nutrients in the waters of the tropical Ocean).
To be able to do all this, they need some help. Corals have symbiotic algae called zooxanthellae living in their skin cells. Think of zooxanthellae as tiny solar-powered chefs living inside coral homes.
They catch sunlight, cook up energy, and share over 80% of the meal with their coral landlords. The coral provides protection and prime real estate with an Ocean view. It’s a win-win (this is what symbiotic means) – until climate change cranks up the thermostat.
It’s zooxanthellae that gives coral its colour. The magical, vivid world of coral reefs is painted by these little algae. Without them, corals are translucent, and the white of their calcium carbonate skeleton shines through.
Why do corals bleach?
The happy relationship between coral and zooxanthellae can be disrupted. When it is, this can lead to the expulsion of the algae from coral tissues, leaving the coral gleaming white (it is a spectrum, coral can partially bleach).
The most common cause of coral bleaching is thermal stress AKA temperature. If conditions aren’t right, the systems that make photosynthesis (plants turning sunlight into food) can break.
When these systems break, they can produce reactive oxygen species (ROS). ROS are produced in normal function, but too many ROS harm the coral. When the coral detects this build up, it acts in self-defence and throws the algae out.
Usually, this is from it being too hot, but the system can be broken when it is too cold, or in too much sunlight, or exposed to harmful pollutants.
That’s a bit abstract. Let’s make an analogy.
Imagine the coral as a battery, and the algae as a solar panel. Normally, the algae are providing energy to the battery from the sunlight. But if the solar panel gets too hot or is exposed to too much sunlight under a magnifying glass, it might start to malfunction. It starts to spark, so to protect itself the battery disconnects. Without its solar panels, our coral battery can only run on emergency power for so long before it’s completely drained.
History of coral bleaching – how long has bleaching been about?
Places like the Maldives, Seychelles, and reefs in the Indian Ocean lost nearly half their coral cover. 2023 saw the start of the fourth global coral bleaching event, that over the next two years saw an estimated 84% of the worlds coral reef areas bleached.
Sounds bad, but this isn’t the end.
Image credit: Great Barrier Reef Foundation
Does bleaching mean coral is dead?
No. A bleached coral is still alive, it just doesn’t have its friend feeding it. This leaves the coral more vulnerable to disease, but also to starvation. Unless our battery reconnects to its solar panel, it will eventually run flat.
Having repeated bleaching events reduces corals’ ability to recover. It’s like punching them while they are down.
When the coral eventually dies, it loses its white look and will begin to get covered with other algae and seaweed.
However, corals have shown us again and again they have an amazing ability to recover when given the chance.
Different species of coral are more tolerant, and different species of zooxanthellae can take more heat too.
Some species of coral bounce back faster than others; the marine equivalent of those friends who somehow recover from a night out while you’re still nursing a headache. The massive boulder corals? They’re the slow-but-steady marathon runners. The branching corals? More like sprinters – quick to bleach, but sometimes quicker to recover.
There is a lot of work going into understanding corals, and reef restoration methods continue to be tested and implemented (read here for more.)
Corals are the poster child of Ocean health. They are impacted by all our Ocean threats, which means you can help wherever you are.
Every time you switch off an unnecessary light, choose a reef-safe sunscreen (free from oxybenzone, octocrylene or octinoxate), or select a sustainably caught fish dinner, you’re casting a vote for coral survival.
The future of coral reefs could be written in bleached white, or in vibrant technicolour. The pen, rather excitingly, is in your hands.
Or more accurately: Why do blue-footed boobies have blue feet?
The Galápagos Islands are full of the weird and the wonderful. One of their most iconic species is the blue-footed booby (Sula nebouxii), a marine bird that is found all along the Pacific coast. It is best known for its blue feet (which it was very creatively named after), making it really cool to look at but, why are they blue? To answer this question, let’s break it down into the how and the why.
The how: What are the mechanisms that cause blue-footed boobies’ blue feet?
Our first answer is potentially a killjoy one; they’re not actually blue, they just appear that way!
Colours most often come from pigments, which absorb specific wavelengths of light, but the blue in blue-footed boobies doesn’t seem to come from a blue pigment. Blue pigments are actually very rare in nature – the funky blue mandarin fish is one of the few examples of an animal that makes any.
Instead, the blue in blue-footed booby feet is likely a structural colour which comes from light being reflected. The way different structures on animal surfaces are organised can affect the way that wavelengths of light reflect off their surface – like in the diagram:
The blue-footed booby has a layer of collagen under its foot skin, and the structure of this collagen likely makes them appear blue by reflecting only blue light wavelengths. This is the case for the majority of blue animals.
Pigments might still play a role though because blue-footed booby feet sometimes appear slightly greener which might be due to yellow pigments (blue + yellow = green!). These pigments are carotenoids which animals can’t actually make themselves. Instead, they get them from their diets and the food they eat can influence what colour they are.
For example, flamingos aren’t born pink – they’re born grey but become pink because of the carotenoids in their food. Similarly, if you eat too many carrots you could turn orange (but please don’t, that would be bad for you)
.In blue-footed boobies, these carotenoids from their diet can affect how bright their feet are. Biologists tested this by changing how much food blue-footed boobies were given – when they didn’t get food, their feet became duller but when they were fed again with fresh fish, their feet became brighter.. This is super cool and also super important to keep in mind for our next question…
The Why: Why have blue-footed boobies evolved blue feet?
The reason that anything in nature looks or works the way it does is because of evolution. Darwin’s theory of natural selection says that traits that increase survival will be passed on so the fact that blue-footed boobies have evolved blue feet suggests they might be helpful in some way. But what advantage do blue feet give them? To answer this we need to understand sexual selection.
What is sexual selection?
Great question! It can be thought of as a special type of natural selection where traits that increase reproduction (instead of survival)will be passed on. This can include animals choosing a mate based on preferences for certain traits, which increases the chances of animals with those traits reproducing and so, the trait is passed on. For example, peahens prefer peacocks that have larger, more colourful tails which means large colourful tails get passed on over time!
As it turns out, female blue-footed boobies prefer brighter feet!
We know this because biologists carried out some fun experiments – they used make-up to make male feets look duller (who says biology isn’t a very serious science?). When males had duller feet, the females were less likely to mate with them. Brutal!
Biologists also did this to males that had already mated with females (because blue-footed boobies don’t lay all their eggs at once). When the feet of these males were made duller, females actually made their second eggs smaller so that they’d hatch smaller chicks. Even more brutal!
This suggests to us that females are deciding who to mate with based on foot colour and if the blue isn’t as bright as they like they want to reproduce with those males less. So, foot colour might be a sexually selected trait because it increases the chances of reproduction for the males!
Why do female blue-footed boobies like blue feet?
As lovely as the blue is, it’s not just that they really like the colour. The stakes are quite high for them; they are choosing males to father their offspring and want to make a good decision. So, if they are basing this off foot colour, foot colour likely contains information that is quite valuable. It is likely a signal.
What are signals? Signals are behaviours or structures that have specifically evolved to change the behaviour or state of others by conveying information. The response of the receiver must also have evolved due to signals – it is important to understand what receivers have to gain from responding to signals.
As we already know, carotenoids from their diet can influence blue-footed booby foot colour. What’s even more interesting is that these carotenoid changes can influence the immune response and foot colour also correlates to immune response.
Females might also be interested in how good of a parent males might be and foot colour might also signal this. When biologists swapped baby birds between nests, they found that the foot colour of the foster father was a pretty good indicator of condition (even though they weren’t genetically related).
So, to summarise: blue feet have potentially evolved because male foot colour might signal their condition, females want to reproduce with good condition males so they choose males based on foot colour.
What about female blue-footed boobies’ foot colour?
Male blue-footed boobies also seem to prefer brighter feet on females but the story is slightly less straightforward.
When female feet were made duller, the effects are mostly after they’ve already formed a pair, Blue-footed boobies form pairs then lay eggs but there is a courtship period before they lay an egg. In this period, females with duller feet received less courtship nest presentation (when birds add materials to nests) both from males they were paired with, and other males.
In the period after egg-laying, making the female foot colour duller also had impacts on how much males incubated eggs. However, this was also affected by egg colour and size, which can indicate offspring quality. When females had duller feet, males incubated more in nests with a large egg but when they had colourful feet, males incubated both small and large eggs. Males also spent less time incubating small-dull eggs than small-colourful and large eggs.
So it seems that female foot colour is signalling something about their condition (and as an extension, the offspring’s) and the way males respond depends on the phase of reproduction they’re in. However, it also seems that foot colour isn’t the only useful indicator; egg size also is.
One explanation might be that females have to decide between investing in their offspring (egg size) and signalling (foot colour) so foot colour might not give the whole picture. The mechanisms and reasons for this aren’t completely understood yet which just means there’s more left to learn about blue-footed boobies – exciting!
It’s not just blue-footed boobies that use signals
Nature is full of quirks! Beyond blue-footed boobies, evolution has brought about an array of interesting signals throughout nature. Animal signals are incredibly cool and incredibly diverse; they come in all shapes and sizes (literally) and some of them are also less honest than others. For example, some mantis shrimp display a claw that looks threatening to scare off intruders even when they are actually weak.
The signals that animals display will evolve to reflect the context in which animals live, which might be the environment or how they interact with species.
For example, yellow warblers (a species of small bird) produce alarm calls to scare off parasites. However, the yellow warblers that live alongside blue-footed boobies on the Galapagos don’t produce these calls. Why? They don’t need to!
They have been geographically isolated from their parasites for thousands of years, while the warblers on the mainland have not. These alarm calls either evolved before the Galapagos warblers became isolated, and they then lost the behaviour, or the calls evolved only in the mainland warblers afterwards. Either way, they reflect the lack of parasites on the islands!
Understanding why animals look or behave the way they do could be very valuable to us. For example, in the blue-footed boobies, their feet could show when their condition is declining. Since we know feet colour has likely evolved to signal their condition, if the foot colour changes, this could be because their food quality and availability has changed. This could signal to us that they’re in trouble!
So, as well as being incredibly interesting, learning more about nature and how species have evolved could also be important to protecting them.
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