Discover the Unique Creatures Living in one of Earth’s Most Biodiverse Marine Environments

One of our planet’s most biodiverse marine environments lies in the middle of the Pacific Ocean, around 1,000 kilometres from the South American continent. This isolated outpost is home to a rich array of marine species whilst the islands here are also house some incredibly unique life. Can you guess where it is?

Of course, it is the Galapagos Islands, which achieved their well-known status after Charles Darwin published his theory on natural selection after spending time studying the wildlife on the islands. In total, 127 islands make up this archipelago, although only four are inhabited and many are mere rocks home to a few seabirds. However, this collection of volcanic rock is almost all classed as a national park, with only 3% of the land area designated for human settlements. The ocean here is protected by one of the largest marine reserves in the world which covers all the islands and extends 40 nautical miles out from their coastlines, totalling an incredible 133,000 kilometres squared. This area is filled with unique endemic species which live nowhere else on the planet and is often referred to as a living museum which helps showcase how the evolution of many species played out millions of years ago.

So why is there so much biodiversity here? The main reason for the incredible variety of marine species is because three large ocean currents all congregate near the islands. Two of these currents carry deep cold water which holds a large amount of nutrients. When these currents hit the sharp walls of underwater volcanoes which help make up the Galapagos, they are forced to rise to the surface, making these precious nutrients available for more marine species. The third current carries warm water and this rare mix of warm and cool water allows a wide range of species to thrive here. The diverse habitats, including coral reefs, wetlands and lagoons also support a variety of species. At the bottom of the seafloor beneath these incredible islands lie the meeting point of three tectonic plates, the Nazca, the Cocos and the Pacific. This means the region sees large amounts of tectonic activity, such as earthquakes and volcanic eruptions and it is actually this activity which formed the islands in the first place. In terms of evolution, these islands are very young, ranging between one and five million years old, meaning we can see species colonising and evolving on them today. Combine all these factors with the islands’ extreme isolation meaning there is no threat from predators and you get some of the unique species we see living there today, such as the giant tortoise, flightless cormorant and marine iguana. Incredibly, more than 20% of the marine species here are found nowhere else in the world! 

Researchers have estimated that an astonishing 2,900 marine species pass through the Galapagos islands, including sharks, turtles, tropical fish and whales but let’s look at some of the more unusual inhabitants. The marine iguana is possibly one of the most famous as it is the only aquatic lizard in the world. It is thought that iguanas may have rafted over to the islands from the continent via a piece of driftwood. Once the survivors landed on the island, they discovered very little to eat and so slowly adapted to eating the seaweed and algae which clings to underwater rocks and tree roots. These scary looking yet gentle creatures can dive under the waves for up to ten minutes at a time in their search for food, reaching depths of around nine metres. However, as these creatures are cold-blooded, they must make their way back to shore before the cold seawater cools their core temperature too much, leaving them sluggish and slow moving. This is why they are often seen sunbathing on rocks, their dark coloured bodies intended to absorb as much of the sun’s heat as possible. They have also evolved to have special glands which clean their blood of the seasalt they ingest whilst diving and their laterally flattened tails allow them to move live crocodiles through the water. Sharp teeth help scrap algae from the rocks and long claws help them grip when strong currents and waves arrive.

A slightly cuter inhabitant is the Galapagos penguin, an endemic species which is the only species of penguin found north of the equator. There are around 2,000 individuals living here and they spend their time hunting for schooling fish such as sardines, reaching a top speed of 35 kilometres per hour! However, these comical birds are actually endangered and are having a hard time surviving on the islands. In 1982, the area was hit by a particularly strong El Nino year, a weather event which caused high temperatures in the area. This meant there were fewer fish to feed on, which lead to a less successful breeding season and as a result, 77% of the penguin population disappeared. Even now, 40 years on, the population has not bounced back to its former size. These penguins are very similar to those found in other areas and dig burrows in which to live. However, the lack of soft ground here means they opt for caves and crevices in the coastal lava. Scientists decided to give these birds every possible chance of survival and began chiselling out small holes in the rock themselves, giving penguin couples a large choice of suitable nests in the hope it would lead to greater breeding success. As this species really struggle to survive in captivity, they only exist in the Galapagos and so conservation efforts here are more crucial than ever.

The seal populations on the islands similarly struggled with the 1982 El Nino event which left food in short supply. The Galapagos fur seal population saw almost all their young lost that year along with 30% of the females. This was particularly devastating for this species, partly because they only give birth to one seal at a time but also because their population was bouncing back from being hunted to near extinction in the 20th century. These animals can be found lolling around on the beaches during the day before hunting at night when prey is easier to catch. Their large bulging eyes help them see well in the darkness, allowing them to keep an eye out for predators but they have been found to avoid hunting under a full moon, knowing they will be too easily spotted by hungry sharks or whales. Many visitors often confuse these fur seals with the Galapagos sea lion but sea lions are not technically true seals as they are able to rotate their hind flipper, allowing them to gallop across land faster than a human can run across the rocks, so think twice before getting too close! Males can weigh as much as four times more than the females but once in the water, they are elegant swimmers diving to depths of 600 metres. As well as contending with warming waters and shark predation, the Galapagos seal populations also have the threats of ghost fishing gear and discarded plastic which they can easily become entangled in. 

These islands are also home to a slightly unusual bird. Of the 29 cormorant species, the Galapagos is home to the only flightless one, whose wings are only a third of the size they would need to be in order for them to fly. For this reason, they are restricted to the beaches of just two islands. This adaptation developed due to the lack of predators on the islands, meaning they never had to fly away from danger. What was much more useful however, was the ability to swim well, allowing them to dive deeper and spear eels and octopus from the sea floor. This is a clear case of the survival of the fittest, as those with powerful hind legs and flexible necks ready for spearing were the most well-fed and physically fit of the population, meaning those were the genes which were passed down to the next generation and the next. However, as the size of their wings shrunk, so did the level of oil produced by them which reduces their waterproofing and this is why you can often see them holding out their wings to dry. This species is particularly vulnerable to fishing lines however, which they can easily become entangled in whilst diving for food. Their nests, located only a few metres from the ocean, are threatened by flooding whilst they would suffer incredibly if an oil spill occurred in the area.

Despite all the protection the national park and marine reserve tries to offer, there are sadly still many threats facing the rare Galapagos wildlife. One of the greatest is the threat of invasive species, with dogs carrying dangerous diseases whilst cats and rats hunt iguanas and seabird eggs. Having evolved in a completely isolated environment for thousands of years, the species here simply are not adapted to contend with new diseases or competition. It is the invasive species that arrive under our noses that pose the greatest potential danger however, as plant spores are carried in on tourists’ shoes, barnacles hitch a ride on boat hulls and algae drifts over the ocean on waste plastic. Already, alien crabs, mussels and worms have made their home here. Soft corals threaten to grow faster than native corals, moss has the ability to kill seagrass and lionfish travelling via the Panama Canal from the Caribbean are known to decimate fish populations due to their large appetite. 

Illegal fishing is also rife in the area as the rich diversity of species here offers a poacher’s dream as they hunt sea cucumbers, lobsters, turtles and sea lion teeth, many of which are used in popular Asian cuisines or traditional medicine. With the marine reserve covering thousands of kilometres, the area is hard for conservation groups to fully patrol. The islands are also becoming ever-more popular, with 30,000 inhabitants and an astonishing 170,000 tourists every year, all of which place pressure on the limited waste infrastructure, meaning pollution incidents are an ever-looming threat. Thankfully, due to the precious and celebrity-like status of these islands, conservation plans are constantly adapting and evolving, much like the islands themselves, giving us hope for the fragile and fascinating life which lives here.

By Neve McCracken-Heywood