Fish that break all the rules by living in the Ocean and streams: 

Look into a river and you will find very different animals to the Ocean, even if they are just a few miles apart. Why are these wet worlds so different? In short – it is all about osmoregulation (explained below). 

Whether you live in the Ocean, in a river, on a mountain or in Thneedville (yes, that’s a Lorax movie reference) – everywhere has its challenges. One of the main challenges of living in saltwater (read more about why the Ocean is salty here) is maintaining the balance of water in an animal’s cells.

What is osmosis?
Water will travel from areas of high concentration to low concentration in an attempt to balance them (this is called osmosis). Salty water has lower water concentration than freshwater. 

Join us to explore the difficulties of swimming between the two worlds, some of the incredible journeys of the fish, like salmon, eels and bull sharks, that overcome them and crown the winner of the wet.  

What is osmoregulation? 

All living things need water, and they need salts. Maintaining the balance of both is tricky – too much or too little of either is fatal.  

Imagine a balloon full of water, but this balloon can let water in and out of it. This is our cell. The water in the balloon (our cell) has a little bit of salt in.  

If you put the balloon in a bucket of freshwater, water enters the balloon (by osmosis) to balance the concentration. This could end up bursting the balloon. Alternatively, putting the balloon in salty water will lead to the water leaving the balloon, shrivelling it.   

Animals living in these environments have to adapt to avoid bursting or shrivelling – neither sound particularly fun.

Fish living in freshwater have to hold on to their salts and avoid water intake. Saltwater fish take in as much water as they can and excrete the extra salts.  

How do freshwater and saltwater fish stay hydrated AKA: do fish drink the water they live in? 

To maintain a good balance of water and salt, fish in different environments alter their drinking, gill function, kidneys and excretion (waste removal).  

Marine fish will constantly drink sea water, getting as much water in as possible. They actively remove salt from the water through cells in their gills. The pee of marine fish is highly concentrated urine (if you get dehydrated, your body does the same – your pee will be very yellow, with little water diluting it), minimising water loss.  

Freshwater fish, on the other hand, don’t drink water. They don’t need to. Think of the balloon example – they are saltier on the inside, so water wants to move in. Freshwater fish easily absorb water through their gills. They use energy to pump salts in, against the concentration gradient – they actively ingest salts. Their pee is very diluted, ensuring they don’t become swamped by discarding lots of water.  

Why can’t freshwater fish live in the Ocean?  

Knowing all that, let’s see what would happen now if we put a marine fish in freshwater. A marine fish wants to lose salt from its body and keep water. Think of the balloon – a marine fish invites water in, pushing salt out. This means the balloon will lose all its salts and get over filled with water. That is one unhappy fish.  

For a freshwater fish in the Ocean, the opposite happens. Used to a world with plenty of water and little salts, the balloon will shrivel as it is filled with more salts and loses water. The bottom line is the same – an unhappy fish.  

Are there fish that can live in both freshwater and salt environments? 

Amazingly, yes. There are examples of fish that can live in both marine and freshwater all over the world. There are two main types.  

1. Anadromous fish are born in freshwater, spend most of their lives in the Ocean and then return to freshwater to spawn.  
2. Catadromous fish live in freshwater most of their lives, returning to the Ocean to spawn. 

We will explore these groups through a couple of their most famous members, as well as a shark that makes it all look easy.  

How do salmon survive in both fresh and salt water?  

Salmon are incredible fish.  

Not all salmon are anadromous: there are Atlantic salmon in North America called sebago, named after one of the lakes they are found in. More Atlantic salmon live in Norwegian, Swedish and Russian lakes; and yamame are a landlocked Japanese masu salmon.  

But some salmon travel thousands of miles between fresh and salt water over the course of their lives.

Chum salmon have been estimated to complete total migrations of over 10,000km (6,200 miles) across the North Pacific from feeding grounds to the Yukon river or streams in Japan.  

Anadromy appears to have evolved at a similar time that the Ocean cooled and became richer in food. This, coupled with the existence of landlocked variations, suggest that salmon were a freshwater fish that took to the sea, although this is not confirmed. What is certain is the incredible journeys and transformations many salmon go through to mate. 

For salmon, the movement from river to Ocean and back to river is integral to their life cycle.

The first few years of a salmon’s life are spent growing in the river, before they go to the food-rich Ocean. Here they gorge themselves, growing very quickly. After travelling many thousands of Ocean miles, they will return to the rivers they were hatched in, to spawn themselves.  

But how do they manage to conquer both environments?  

Through hormonal changes, salmon make behavioural and physiological changes to the ways they manage their osmotic balance. In freshwater, they won’t drink water – when in salt water they will drink a lot. Hormones change the fish’s physiology, increasing the number of ion transporters in the gills and kidneys to process the salt balance.  

The change is a costly one though, as salmon won’t feed during their return to freshwater, relying on fat reserves built up through years in the Ocean. They battle up their rivers, overcoming waterfalls, predators waiting on the banks and their own failing bodies to reach the same spot they hatched in. Here, they will spawn.  

For most of these fish, it is the last thing they do.  

What can salmon teach us? 

Just as rivers are the connection between us and the Ocean, salmon are among the clearest species to bridge that gap. And they feel the impact of people more keenly. Rivers are the frontlines, and salmon are in the trenches.  

Salmon rivers are best in old forests, as the tree roots hold the banks together and keep the rivers form – holding it narrow and fast flowing. Where forests are lost, the river can widen and the salmon population diminishes. And as we build dams to harness the power of the rivers, we block the salmon from getting home.  

The populations of salmon in different rivers show far more genetic variation than between people. Each salmon is genetically coded for its river home. Climate change, pollution, human development and fishing – salmon deal with a lot.  

But their adaptability is shown time and again. The genetic diversity they show allows them to overcome the challenges they face. Just as they are able to thrive in these two different worlds, they can take on the new world we are shaping.  

What do you call returning to the Ocean to reproduce? 

Catadromy is the mirror of salmon – starting life in the Ocean, living in freshwater and returning to the salt to spawn.  

European eels begin life as eggs riding Ocean currents, drifting through the Sargasso Sea near the Bahamas. They hatch into small, transparent, leaf-shaped larvae called leptocephali. Like so many (hungry, well-teethed) leaves in the wind, the Ocean carries the eels to the coasts of Europe, a journey taking 2-3 years.  

On reaching the coast, they metamorphose (change body shape) into glass eels – still small and see-through but eel-shaped. After up to a year, they change again into elvers (juvenile eels) and begin to travel up rivers. Here, they change again into yellow eels and can remain in freshwater for up to 20 years until they reach sexual maturity. 

This means an eel can be 23 years old before reproducing. When their time comes, they become silver eels, migrating down rivers towards the Ocean.  

How do eels switch between living in fresh and saltwater? 

For the elvers and glass eels, they need to do the same as our salmon. They alter the salt uptake of their gills via specialised cells, increasing it in freshwater and decreasing in saltwater.

For many years, European eels were characterised by mystery. They were well known in the rivers of Europe, yet no one could find baby eels. Greek philosopher Aristotle suggested that they just appeared out of the mud, and this was the general belief for almost 2,000 years.  

It was Johannes Schmidt, a Danish biologist working in the early 20^th century, who began to unveil the elusive eels. By finding progressively smaller eels across the Ocean, he followed the trail of breadcrumbs to the Sargasso Sea. He couldn’t find any spawning, but he drew the metaphorical arrow.  

It wasn’t until 2022 that we found the first direct evidence of adult European eels travelling to and reaching the Sargasso Sea. This study also shows us just how far the eels travel – up to 8,000km. If you’re ever lucky enough to see one of these eels, appreciate just how far it has come, and how far it still has to go.

The eels adapt twice, changing their whole bodies to swap salt for fresh and back. On the way back, the silver eels don’t feed. As with salmon, they rely on fat reserves for their journey, and their bodies slowly disintegrate, and once they have reached their spot, they reproduce and then die.  

But the switch doesn’t always have such dire consequences.  

Are bull sharks the best sea-swappers? 

Yes. Bull sharks (Carcharhinus leucas) are the aquatic conquerors supreme. As we have seen, moving between fresh and salt water is tough. Most salmon only do it once, some can manage it a couple of times, their bodies failing them under the stress. Eels change their whole bodies when they make the switch. Yet bull sharks can move between fresh and saltwater with apparent ease.  

They have been found in unexpected places. In Africa, bull sharks are known as Zambezi sharks as they are found deep into the Zambezi river. They were initially described as a different species* – because no one expected a bull shark there. In Brisbane a bull shark was spotted swimming the streets after flooding in 2011, and they have been to Baghdad up the Tigris. They have even been found in Alton, Illinois, 2,800 km (1,740 miles) from the Gulf of Mexico.   

The ultimate tourist? A bull shark was reported in the upper reaches of the Amazon, in the Ucayali River, Peru. Nearly 5,080 km (3,157 miles) from the Ocean.  

How do bull sharks do it? 

Ready for some high-density science?  

They change how salty they are (in the balloon). In the Ocean, bull sharks’ blood is at least as salty as the water they are in due to the levels of urea and trimethylamine oxide (TMAO). But when in freshwater they excrete much more urea, lowering the salt concentration of their blood to minimise the gradient (the difference in saltiness).  

However, they are still more salty than freshwater, so they absorb water and lose salts through their gills. They change their salt and water processing to match their environment.  All sharks have rectal glands through which they excrete excess salt when in the Ocean. When in freshwater, bull sharks reduce the activity of their rectal gland (which normally gets rid of all the extra salt a shark absorbs when in the Ocean) to preserve salts. The kidneys of bull sharks in freshwater go into overdrive, producing large amounts of dilute urine to avoid the balloon-popping scenario. Both the kidneys and the gills are triggered to actively uptake salts, while the liver changes urea production. 

On top of all this, bull sharks have to deal with the different densities of salt and freshwater. As anyone who has visited the Dead Sea will tell you, more salt = floaty. So, bull sharks in freshwater reduce the densities of their livers to counter their reduced floaty-ness. Still, living in freshwater really does drag them down, which may be why they still mostly prefer the Ocean (can’t say we blame them).  

Why do these species matter? 

These fish, as with our rivers, are great connectors. Their journeys are important to all those they encounter. By travelling between the separate biomes, they transport nutrients and link ecosystems, strengthening them.  

They are used as indicators of water quality and ecosystem health and provide food sources. Something harder to measure is their cultural importance, which resonates through many different social histories – they bring us closer together as well.

The challenges of moving between the Ocean and its fresh-water fingers are staggering. Yet these fish tackle it head on.  

Which do you find more impressive; the salmon battling bears and waterfalls to return to its river home; eel larvae drifting thousands of miles and swimming back, changing their whole body to tackle each step; or the bull shark that is just at home in the heart of the Amazon as a reef in the Indian Ocean?

From the legend of the salmon to the mystery of the eels to the euryhaline hero the bull shark, these fish are truly conquerors of the coast.  

Book recommendations from our Marine Scientist 

When I am writing my articles, I use a variety of sources. One of the most engaging are the books. Here are a few I used for this article, do let us know if you have a read, and watch out for more recommendations.  

Blowfish’s Oceanopedia 

Salmon by Mark Kurlansky

Sharks of the World  

Additional sources:
*Peters, W. C. H (1852): Hr. Peter legte einige neue Säugethiere und Flussfische aus Mossambique vor. – Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich Preussischen Akademie der Wissenschaften zu Berlin. Aus dem Jahre 1852. Berlin, pp. 273–276. (not available online)

Post by

Will Steen

Our planet is known as the blue planet, over 70% of it is covered in water, most of which is the Ocean.

This water shapes our landscapes, influences where life thrives, affects the health of our Ocean and the weather in our skies. 

The Ocean is always closer than you may think (not in a sinister, about-to-jump-out-at-you way. It’s more of a realising-it-is-Thursday-and-the-weekend-is-only-round-the-corner-kind-of-way). 

Take a moment, think: what is different from the water you drank this morning (if you haven’t had any, this is your reminder to drink some) and the water lapping up a warm tropical beach? Every drop of water, from what’s come out of your tap to the water five kilometres deep in the middle of the Pacific, is connected.   

It is all just at different points in the water cycle. 

How does the water cycle work? 

There are four processes that drive the water cycle: evaporation, transpiration, condensation and precipitation.  

Water is warmed and evaporates, becoming water vapour. Amongst the many good things plants do, they release water into the atmosphere through transpiration. These two processes are responsible for putting water vapour in our air, our atmosphere.  

Water vapour is invisible.  

The steam we see when we boil the kettle (or the clouds in the sky) is water becoming liquid again, on contact with the cooler air. That is condensation, the transition back from gas to liquid. When enough of this cloud cools and turns to water, it will clump together and fall as precipitation (snow, hail and rain).  

How is the Ocean connected to the water cycle? 

This water then starts its journey back to the centrepiece of the cycle: the Ocean. 

The Ocean holds 97% of the Earth’s water – approximately 1.34 billion cubic kilometres. 86% of evaporation is from the Ocean, and 78% of precipitation re-enters the Ocean, directly. You can’t have the water cycle without the Ocean. 

Ice holds 2% of global water and just 0.001% is in the atmosphere – that is all the clouds in the sky.  

But if we add all that up, there’s a little still on the table – or more accurately, on land. That is the groundwater, lakes, swamps and the rivers. Rivers make up only 0.0002% of the total water on Earth.

What does the water cycle do? Why is it important? 

There are five main points of importance for the water cycle: 

1. Regulating Climate:  
The water cycle helps distribute heat around the globe, influencing weather patterns and climate conditions. It absorbs and releases energy during evaporation and condensation, which affects temperature and weather. 

2. Sustaining Ecosystems:
The water cycle provides the water necessary for plant growth and supports all forms of life by delivering freshwater to ecosystems through precipitation.

3. Shaping Landscapes:  
The water cycle contributes to erosion and sedimentation, reshaping geological features over time. 

4. Circulating Minerals and Nutrients:
Water transports minerals across the globe, enriching sea and soil and supporting plant life. 

5. Maintaining Freshwater Supplies:
The cycle replenishes freshwater sources, such as rivers and lakes, which are essential for human consumption and agriculture. 

Imagine a world without a water cycle – what would it look like?  

How is the water cycle changing?  

Human activity is interfering with the hydraulic cycle at every stage.  

Deforestation means less trees to transpire and absorb rainfall. Urbanisation interrupts drainage and can increase surface runoff. When it rains, the water that would have been absorbed by the ground now hits tarmac and runs down the road. 

The single greatest threat to the water cycle, and therefore to all life on Earth, is climate change.  

How is climate change impacting the water cycle?  

Climate change is intensifying the hydraulic cycle. Higher temperatures lead to more evaporation, more water vapour in the atmosphere, which results in more intense storms and rainfall. At the same time, droughts are becoming harder to predict and more severe.

These changes directly threaten our lives. 

Water is the life blood of our planet, and the water cycle is the pulse that keeps it alive. 

The hydraulic cycle regulates our climate, fertilises and maintains our ecosystems and shapes our world. We are changing it through our actions and activities.  

Understanding this cycle is the first step, but acting to protect it is the most important. The question is: what will we do to safeguard the blue heart of our planet? 

Post by

Will Steen

Everyone knows the Ocean is salty. But how did it get salty? Where did the salt come from? Is it getting more salty?  

These are all great questions to bring up as you ask for the salt over dinner. And after this explainer, you can answer them.  

Why is the Ocean salty: Explained 

Imagine a bowl. Now pour some slightly salty water into the bowl and put it into the sun on a hot day. Eventually, the water will evaporate, leaving that little bit of salt behind.  

Now, add some more slightly salty water to the bowl. The left-behind salt dissolves and mixes, making saltier water. Leave it in the sun again, the water will evaporate and leave salt behind. If you now attach a constant stream of slightly salty water into the bowl, you have a little model of our Ocean.  

Just like in the above example, rivers (the stream) bring tiny amounts of salt into the Ocean (the bowl) and the sun evaporates the water, leaving behind the salt. These amounts have built up over huge periods of time.  

Where does the salt in the Ocean come from? 

Most of the salt in our Ocean comes from rocks on land. Carbon dioxide in the atmosphere dissolves into rainwater, making it slightly acidic. When it rains, this slightly acidic water can dissolve the rocks it falls on and over, in the form of ions (charged molecules).  

These ions, mostly sodium and chloride, are carried into rivers, which carry them into the Ocean.  

Some salt also comes from volcanic activity, where elements from the Earth’s core can be released into the Ocean through underwater volcanoes and hydrothermal vents.  

Why aren’t rivers salty? 

Rivers are, very slightly salty. Depending on what the water has run over on its journey (rocks, decomposing plants, your ex’s belongings etc.), the contents of each river, including salt levels, varies. 

For water to be considered freshwater, its salt content must be less than 0.05% salt (saltiness is also commonly shown as parts per thousand or ppt: 0.05% is 0.5ppt). This means freshwater can still have a little salt in. 

Between 0.05 and 3% salt content is brackish water, and saltwater is between 3 and 5% salt. Above 5% (or 50ppt) salt is brine.

What are the saltiest bodies of water in the world?  

One of the saltiest bodies of water is the Dead Sea. It was cut off from the river Jordan by damming in the 1950s, so there is no significant freshwater input. This means the water is gradually disappearing, as the water level drops close to 1.21 metres (4 feet) every year.  

Think back to our bowl of water example – the water evaporating leaves its salt behind, so the sea is getting more salty. Salinity is roughly 337ppt (33.7% salt) – ten times the average of the Ocean.  

But it isn’t the saltiest – that title goes to the Gaet’ale Pond in Ethiopia. It is a volcanic spring, with a salinity of 433ppt. You wouldn’t want to swim there – CO2 bubbling up presents the risk of suffocation and the hot, acidic water could leave painful burns.    

Does the Ocean vary in saltiness? 

Yes. Where there is more freshwater entering the Ocean, it’s less salty. This can be in places that rain a lot, have lots of rivers entering, or have ice melting. On average the Ocean has a salinity of 35 ppt. 

Have a look at the picture below. The red areas show high salinity, purple areas are low salinity. Try and work out why each area is the colour it is.

The Baltic Sea is very enclosed, has lots of river input and rain, and little evaporation, so the Ocean surface can be around 10ppt. The Red Sea is much higher, 40ppt. This is due to very little rain or river input, and high evaporation.  

Is the Ocean getting saltier? 

The Ocean is now more in balance. If we go back to our bowl example, there is a bit we didn’t tell you about. Salt can mineralise at the bottom of the bowl – solidifying into rock, leaving the water. The amount of salt that mineralises is the same as the amount entering, so the Ocean stays the same level of salty.

So, with the next salty mouthful of Ocean water you get – thank the rocks and the rivers (and the rain and the sun).

Post by

Will Steen

Approximately 926 km (575 mi) off the coast of Ecuador lie the Islas Encantadas: the Enchanted Islands.

Better known as the Galápagos Islands, this collection of islands is named after the tortoises that once covered their shores.

Now, fewer in number (reduced to 15,000 from an original 250,000), these giant shelled residents reflect the degradation that the islands are experiencing. 

However, not all hope is lost. As our knowledge and appreciation of these incredible ecosystems has advanced, the Galápagos tortoise and the Galápagos Islands are becoming successful conservation stories. 

What is so special about the Galápagos Islands?

Below is a quote from the renown naturalist Charles Darwin. He is attributing the inspiration of his theory of evolution to the animals of the Galápagos Islands. Indeed, they are described as a ‘laboratory for evolution’, as they have a small number of species in distinct habitats, making them easy to study. 

Explore who Darwin was and how the Galápagos featured in his work here. 

“I have been now ever since my return engaged in a very presumptuous work and which I know no one individual who would not say a very foolish one. 

I was so struck with distribution of Galápagos organisms and with the character of the American fossil mammifers (AKA mammals) […] At last gleams of light have come, and I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable.”- C Darwin, 1844 to Hooker 

Starting with Darwin’s visit in 1835, the islands have continued to be a focal point for scientific research and tourism.

Carrying his legacy are Peter and Rosemary Grant in 1973.  The two scientists lived the dream, moving to a remote island and watching birds. They studied the finches of the Galápagos and how populations responded to environmental conditions (for example, drought). Their observations were the first measurements of evolution in action.  

Made a UNESCO World Heritage Site in 1978, the Galápagos Islands are a place that showcases the wonders of the natural world.  

The unique species capture the imagination. They also act as a reminder of the stewardship humans have for our natural world.  

What threats do the Galápagos face? 

The Galápagos biosphere face human-made threats. Invasive species, direct human impacts such as building and pollution, climate change and overfishing all contribute to the decline of the species that make the islands unique.

How do invasive species threaten the Galápagos Islands? 

Humans have explored the world, linking remote places like never before, and  with us, we have brought some hitchhikers. According to the Charles Darwin Foundation, there have been 1,978 introduced species in the Galápagos, and of these, 1,898 have become established on the islands.  

Some were intentional: early pirates left goats and pigs on the islands as a food source they could come back to. Later, ornamental plants were brought for gardens, and cats and dogs for companionship.  

Others were stowaways. Rats and fire ants are two examples that managed to catch a ride into this haven, via ships or in delivered goods.  

This has made life harder for the residents. The Galápagos tortoises now have to compete with herds of goats for the vegetation they eat and hatchlings can be attacked by fire ants, cats and rats. Blackberry bushes out-compete native plants, killing off more food for the tortoise. Spanish cedars (a mid-sized tree) grow in thick stands making it challenging for the tortoises to gain access.  

Their world is changing faster than they can keep up with.  

What direct human impacts affect the Galápagos? 

More people live on and visit the Galápagos islands than ever before. The population has grown by 300% since 1990 and in the first half of 2024 alone the Galápagos accepted 142,473 visitors. 

As humans settle, we use land for agriculture and residence, reducing the land available for resident animals. This phenomenon is called land-use-change and is one of the biggest threats to global biodiversity today.  

How is pollution impacting the Galápagos Islands?  

The islands waste collection grew 66% over the last decade to 28.6 tonnes per day, which needs shipping back to the mainland.  

But it is the waste that isn’t collected that causes more of an issue. According to Plastic Pollution Free Galápagos, over 8 tonnes of plastic is removed from the beaches each year, and 38 species have been entangled in or ingested plastic. Much of this plastic pollution this comes from the mainland, following the same route as the residents’ ancestors.  

How is climate change impacting the Galápagos Islands? 

The Galápagos thrives because of the Ocean surrounding it. Fed by nutrient-rich currents from the deep, the Ocean is full of life.  

However, climate change is slowing Ocean circulation, increasing the acidity and lowering oxygen levels of the water, reducing the amount of food supporting life on these islands. It also interferes with El Nino.  

What is the El Nino event?  

El Nino is a naturally occurring event, characterised by changes in Ocean upwelling and climate.  

Climate change is predicted to vary the strength and frequency of this event. Species on the Galápagos islands have adapted in incredible ways to deal with El Nino. For example, marine iguanas can shrink; reabsorbing bone mass, to deal with the scarcity of food.  

Climate change has major influence over the way our planet functions, coupled with the loss of population and resilience caused by other factors, populations will be stressed more than before.  

How does overfishing impact the Galápagos? 

The waters of the Galápagos are exceptionally rich and contain some of the highest densities of reef fish anywhere in the world.  

Largely, high densities of sharks (lots of sharks usually means a healthy Ocean). It is also a key spot for the largest fish in the Ocean, the whale shark – with 700 adult females passing through every year, most of them pregnant.  

We suspect this could be the location whale sharks come to give birth – hidden around the Galápagos could be the nursery for baby whale sharks!! 

Fishing has destroyed the majority of the coral reefs in this archipelago (an extensive group of islands), and sharks are targeted for their fins.  Hammerhead populations have seen a 50% decline since 2000. 13 of 28 species tracked over the last 20 years have declined sharply. 

In 2020, the tag of a whale shark called Hope suddenly logged fast movement above the surface of the water, indicating she had been caught by a fishing vessel. In 2017, a fishing boat containing the fins of 6,620 individual sharks was seized.  

The fish lover in us doesn’t like this. Losing sharks and habitats can disrupt the ecosystem, meaning less fish for feeding people. Most people like people, so most people also won’t like this.  

What is being done to protect and restore the Galápagos Islands? 

But the Galápagos is proving we can make a difference.  

As a focal point for nature and evolution, it is only fitting that the Galápagos Islands are also a focal point of conservation efforts.  

Tourism is utilised to support the islands, with an entry fee of $200 per person. 40% of this goes directly to conservation efforts, ensuring the attraction of the islands is preserved by those attracted to it.  

Conservation efforts in the Galápagos: 

Conservation efforts use camera traps, satellite tags and intense gardening to give the natives a hand.  

The Galápagos Conservation Trust is spearheading an incredible citizen science project, Barcode Galápagos, aiming to describe the genetic profile of all species in the Galápagos. Employing local people, the venture will enable identification of new invasive species, tracking of the health of the Galápagos and tracking of illegal pet or shark fins. 

In light of the impacts of overfishing, Ecuador has protected 198,000 square km in the Galápagos Marine Reserve, including a 30,000km² area where any fishing is prohibited. Research is being used to guide fishing practices. The aims are to reduce by-catch (the accidental trapping of unwanted marine creatures by commercial fishing nets) and waste. This ensures sustainable fishing practice, producing more fish with less effort. 

For our Galápagos tortoises, new conservation efforts aim to eradicate the invasive species threatening them, and even bring back species that were driven to extinction. 

Genetic analysis of surviving tortoises on the islands has found traces of Floreana tortoises, a species declared extinct in the 1850s. Through selective breeding programs, the Floreana Giant Tortoise could soon be roaming the islands again. 

Project Co-Galápagos targets a growing global issue – dependence on tourism and how to make it more environmentally friendly.  Co-Galápagos aims to be the global example of developing local communities in symbiosis (what a great word) with nature.

What does symbiosis mean? Symbiosis the interaction of different organisms living in close physical association, but in benefit to them both. 

How does the Galápagos help us protect our world? 

Our abilities to understand the natural world have increased since Charles Darwin first sketched a marine iguana. We know and understand so much more about the Galápagos Islands, and the world, than we once did.  

This enables us to better protect it. The Galápagos are a unique environment due to their isolation, distinct habitats and rich biodiversity. They give us a microcosm of our planet. Charles Darwin realised this, and the islands gave him a chance to better understand the world by observing them.

Now, our world is changing, and again the Galapagos is the perfect place to understand the effects of those changes. 

The Galápagos Islands have provided inspiration in our understanding of the natural world, they are giving us the chance to understand how best to protect it.  

Post by

Will Steen

A fresh breeze, the sounds of gulls calling, cold sea spray touching the cheeks, the slightest hint of rotten eggs in the air.

What was going through the mind of 26-year-old Charles Darwin on 15 September 1835, as he stood on the deck of HMS Beagle with the shapes of the Galápagos islands approaching? 

His letters home suggest two things. First, that he was homesick. Understandable after nearly four years away from England, which he had left at 22 years old – he truly was the pioneer of the gap year. He was also incredibly excited.

What Charles Darwin observed during his five week visit to the Galápagos would plant the seeds that would eventually grow into his Theory of Natural Selection.   

In this article we will explore who Darwin was, how he came to be on the Galápagos, and the sparks of inspiration that he found there for his theory of evolution.  

Who was Charles Darwin? How did he end up on the Galápagos? 

Charles Darwin was nearly a little-known priest in Shropshire, in England. His father wanted Charles to get good employment, either following his footsteps to become a doctor or to become a man of the church. Aged 16, his father sent him to medical school in Edinburgh. His foray into the medical world was brief, however. After witnessing the brutality of surgery without anaesthetic (on a child), Charles knew he was not to be a doctor. He left the course after only two years.  

In those two years, Edinburgh did give him some important foundations; Darwin was taught geology, biological classification and taxidermy. He was also exposed to the radical ideas of the day. These denied the Divine design of humans and suggested that animals shared human mental abilities, like thinking, remembering or making decisions.  

On leaving Edinburgh he went to Christs College, Cambridge University, to complete a degree and take holy orders – ministry beckoned. He breezed through the degree and enjoyed his time at Cambridge. He would go out drinking, shooting and beetle collecting. College folklore claims the sounds of his shotgun would ring out as he fired blanks to extinguish candles in his rooms. 

It was at Christs that he met Professor John Stevens Henslow. Professor Henslow encouraged discussion around natural philosophy and introduced Darwin to some of the greatest minds of the era.  

It was Professor Henslow who got Charles Darwin on the voyage to the Galápagos. The Professor had been approached to be a naturalist and gentleman companion to accompany Captain Robert FitzRoy on a ship called HMS Beagle. His wife was… unwilling to let him go, so he instead recommended his protege, Charles Darwin.  

What was the mission of the HMS Beagle? 

The Beagle was sent on a two-year mission to map South America. It ended up being a five-year circumnavigation of the globe. Captain FitzRoy had completed a similar mission the year previous, and had thought a ‘naturalist’ would benefit the scientific productivity of the voyage. Few could argue with the scientific output of the Beagle.  

It was the Ocean that really started Darwin’s thinking about evolution.

While at Edinburgh Charles Darwin would collect sea slugs and sea pens, and was mentored by Robert Grant, an expert on sponges who encouraged him to study marine invertebrates. He began exploring classification and gave talks on his findings at the university.  

Onboard the Beagle, he made himself a plankton net with which he drew up trawls full of Ocean life. He wrote, “Many of these creatures, so low in the scale of nature, are exquisite in their forms and rich colours. It creates a feeling of wonder that so much beauty should be apparently created for such little purpose”.  

If the accepted worldview of the time was correct, and God made everything for humankinds’ benefit, why do these tiny organisms exist out at sea where no one sees them? The Ocean was creating Darwin’s first glimmers of insight.  

What are the Galápagos Islands? 

About 1,000km off the coast of Ecuador in the Pacific, are a group of islands called Islas Encantas, or Enchanted Isles. They are better known as the Galápagos.

The initial descriptions of the islands are at odds with the image of “enchanted islands”. The first man to discover the Galapagos, Fray Tomás de Berlanga, speaks of the inhospitality and lack of water on the islands.  

Captain Fitzroy, leader of the expedition Charles Darwin was part of, describes the first viewing of the Galapagos: “Black, dismal-looking heaps of broken lava, a shore fit for pandemonium”. Darwin himself compares them to the iron-foundries of Staffordshire, or the furnaces of Wolverhampton. Hardly flattering for either party.

So, not a tropical paradise. 

The word galápagos comes from the Spanish word for saddle, the shape of some of the shells of the most famous residents of the islands – tortoises.  

Darwin reported that locals could determine the island tortoise by the shape of its shell. The implications of this did not occur to Darwin until later.

Unfortunately for science, and the tortoises, they were an excellent food source for long voyages. The Beagle collected 50, none of which made it back to England.  Tortoises became extinct on the island of Floreana in the 1840s, just ten years after Charles Darwin’s visit. However, careful genetic analysis and targeted breeding has created the possibility of de-extinction (click here for more). 

The names of the islands and the tortoises immediately hint at the special nature of the Galápagos.

From their discovery, the Galápagos were renowned for their rich biodiversity. 

Whalers came to benefit off the many sperm whales that gathered there, and tales of the lizards that lived there reached across the globe. 

It is important to clarify that Darwin was not struck with a bolt of genius immediately on seeing the islands.  

He was inquisitive, curious and observant about the natural world. He saw many things in the Galápagos, and documented and collected evidence he would later use to build and justify his arguments for evolution. 

But what was Charles Darwin’s theory of evolution? 

Darwin’s thinking was radical at the time. He was opposing the accepted position that species were ‘fixed’ – unchanging. This was tied into the strong Christian influence of the time – God had created all life, and it hadn’t changed since – with humankind superior to all. 

His work was an attack on the accepted views of his time: that man was supreme by divine making, and the order of the world was fixed. 

Observing the animals of the Galápagos and beyond, Darwin’s theory of natural selection proposed that the natural world was ever-changing, evolving.  

Within this, the idea that species change over time. Further, he suggested a world in which animals were not below humans, but simply different, surviving using different strategies.  

Darwin himself recognised that his theories opposed widely held beliefs. He likened publishing his work to confessing a murder. 

What did Charles Darwin find on the Galápagos? 

Darwin was in the archipelago (an area that contains a group of islands) for five weeks. During that time, he explored the islands, at one stage camping for nine days with only a few others, and collected specimens.  

Birds, reptiles, plants and plankton were all stashed in crates on board the Beagle. He was intrigued by what he found, writing in his journal, “the natural history of these islands is eminently curious, and well deserves attention”.  

What’s the deal with Darwin and finches? 

If you have heard of Darwin, you have probably heard something about finches. He collected loads of finches from the Galápagos, and they became an iconic example of his theory of natural selection.  

The birds would even come to be named after the naturalist – Darwin’s finches. 

Far from being an example of his genius, the finches are an example of Darwin being human.  

He misidentified many of the finches he collected as blackbirds, wrens and “gross-bills”, and did not write down which bird came from which island. It was ornithologist John Gould of the Zoological Society of London who reported that this collection were all finches.  

After this realisation, Darwin looked again, and the differences in their beaks does lead him to comment “one might really fancy… [that] one species had been taken and modified for different ends”. However, his poor documentation meant they could not be used as evidence in his work, and they do not appear in his book.  

Modern work has made the beaks of finches a poster child for natural selection. It was a clear visual example of the adaptions that can allow different animals to survive.  

On the Origin of Species: Darwin’s work, published 

Darwin held the Galápagos dear for the rest of his life. On The Origin of Species, his seminal work on natural selection, was not published until 1859, 23 years after returning to England.

The first sentence of the book affirms the importance of the voyage in developing his theory of evolution:  

“When on board H.M.S. ‘Beagle,’ as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers.” 

In the interim, Darwin had been gathering evidence and forming arguments, bracing for the backlash and interrogation his theory would receive.  

How was Charles Darwin’s theory of evolution received?  

Darwin’s theories certainly made a splash.  

The book sold out the first edition before being released, and divided opinion.  

Predictably, the Church took a strong stance against it, along with some prominent scientists such as Darwin’s former Cambridge peer, Adam Sedgewick. International press put out cartoons and insults, often focused on the idea that humans descended from apes.  

But many scientists, especially geologists, supported Darwin’s work. Atheists were especially enthusiastic.  

Charles Darwin kept in close correspondence with supporters and opponents alike. Debate continued for decades after, until his theory was general accepted in the 1940s. 

The book went to six editions during Darwin’s lifetime and is now seen as one of the most important scientific books ever written.  

It fundamentally changed how people viewed the natural world and the place of humans within it; a lifetime’s work, from a man that explored and observed, inspired by the Ocean and the Galápagos.  

Quotes from Charles Darwin: Even the best scientists have bad days  

We can all relate to Darwin, on a very personal level, after reading some of his journal inserts and letters. Here are a few quotes that remind us even the brightest minds have down days:  

“But I am very poorly today & very stupid & hate everybody & everything.” – C. Darwin, letter to Charles Lyell 1861 

“I am rather low today about all my experiments, – everything has been going wrong” – Letter to W. D. Fox 1855 

“I beg a million pardons. Abuse me to any degree but forgive me- it is all an illusion (but almost excusable) about the Bees. I do so hope that you have not wasted any time for my stupid blunder. – I hate myself I hate clover & I hate Bees-” Letter to John Lubbock, 1862 

“I am very tired, very stomachy & hate nearly the whole world. so good night, & take care of your digestion which means Brain” – Letter to T. H. Huxley, 1860 

Thank you to Prof David Norman of Christ’s College for his time and writing. 

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Will Steen