Galapagos Marine Iguana – Galapagos Islands
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The Galapagos Marine Iguana is one of the more curious creatures found at the Galapagos Islands. It is the only lizard in the world to have learnt how to swim and dive. They can physically shrink in size when times are tough. Marine iguanas are found in contrasting colors and sizes on different islands. Plus they sneeze salt from their nostrils. Curious creatures indeed! Marine iguanas are a common Galapagos sight, and very popular with tourists. So, let's get to know the Galapagos marine iguana a little better.
Read on for everything you need to know about the Galapagos marine iguana. Where and when can you them? What unique evolutionary adaptations have they made? Plus lots of interesting marine iguana facts.
The Marine Iguana is a Galapagos ENDEMIC SPECIES.
Conservation Status: Vulnerable
Scientific Name: Amblyrhynchus Cristatus
How To See A Marine Iguana At Galapagos?
The Galapagos Islands is the only place in the world where you can see Marine Iguanas. They are common sightings right across the archipelago, so the best option to see them is aboard a Galapagos Cruise, or a Land Tour. Marine iguanas can be spotted in large colonies on land, or when snorkeling.
These amazing reptiles are popular with tourists for their tame nature and Godzilla-like appearance. But not all visitors have been equally impressed. Famous botanist Chares Darwin referred to marine iguanas as: “most disgusting, clumsy lizards”, and “Imps of darkness” during his voyage on the HMS Beagle. So opinions are divided, but few can fail to be impressed by their unique evolution and adaptations.
Where to find marine iguanas?
Galapagos marine iguanas live right throughout the islands. Cruise visitors can see particularly large colonies on Fernandina, Española, Santa Cruz and Isabela Islands. If you are on a land trip then check out Tortuga Bay Beach and Puerto Villamil Beach.
Typical Galapagos marine iguana habitat is on sandy shorelines close to black lava rocks. They need sandy terrain to dig their burrows, while the black lava provides protection during the day. Of course they also need to be close to the sea, for daily dives for food.
When to see a Galapagos marine iguana?
Marine iguanas can be spotted all year round, they are always active. Mating season is typically from January to March, with baby marine iguana hatchlings emerging 3 months later.
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Everything You Need To Know About Galapagos Marine Iguanas
Marine Iguana Appearance
Marine iguanas are most easily differentiated from their Land Iguana cousins by color and size. While Land Iguanas are yellow, Marine Iguanas are a shade of black or grey. This is necessary for these cold-blooded reptiles to to absorb sun and maintain warmth. Marine iguanas are also smaller than land iguanas.
In appearance, marine iguanas look like large lizards. They have long tails, a spikey dorsal fin, heavily scaled face and strong clawed feet.
Size and color varies between different marine iguana subspecies on each island (see facts section below).
Galapagos Marine Iguana Adaptations
Marine Iguanas are descended from a South American mainland Iguana species. They originally arrived to Galapagos long ago, floating on logs or foliage along ocean currents. But the volcanic habitat at Galapagos is harsh, so they needed to adapt and evolve to survive here.
The main priority of course is food. The original iguana arrivals were land iguanas, but the only green food source was found in the sea. So they had to learn to swim and dive in order to eat, and evolved into the Galapagos marine iguana species we find today.
Various Marine Iguana adaptations were necessary to make this leap into the water. Their respiratory system transformed to allow deep diving. They evolved a special blood pigment that holds more oxygen, essential for long dives. Their teeth became sharper to saw algae away from the rocks. Long claws developed to grip onto slippery rocks underwater. Tails became streamlined to steer expertly when swimming. A flatter snout gave easier access to food on the rocks. Their unique nostril glands allow them to desalinate after swimming. Their skin also turned darker for better sun heat absorption to keep them warm in the cold Galapagos waters. All in all, quite a remarkable transformation!
So why did the land iguanas that we see today at Galapagos not evolve in the same way? Land Iguanas descended from a second wave of mainland iguana arrivals a long time afterwards. So perhaps they have not had enough time to adapt to the same extent. Also land plants had begun to colonise the islands by that time, so cacti and other plants provided more convenient food for them.
Marine Iguana Behavior
Marine Iguanas live together in large colonies. Visitors can often observe them lying one on top of another in group photogenic poses. This behavior is very important to increase body temperature. In the morning marine iguanas sunbathe together in this fashion, until their body temperature is high enough to enter the cold water. This often takes up to several hours.
Now it's time for food! Marine iguanas dive searching for algae on volcanic rocks. Their strong claws grip to the slippery surface, while sharp teeth pull off food.
Galapagos marine iguana mating season begins in January. At this time it common to see males battling over turf, charging each other and "locking horns". Every male wants to control his own harem of females, and size it turns out is important after all. Females often select larger males. Each female lays 2 or 3 eggs, which she buries in a burrow, her job is now over.
Marine iguana baby hatchlings emerge 3-4 months later, and are on their own from the off. Baby marine iguanas have a long list of terrifying predators, from Galapagos hawks to snakes. Generally speaking, larger babies have a higher probability of survival. The reward for marine iguanas that do reach adulthood is that they no longer need to worry about getting eaten on land.
One final noteworthy marine iguana behavioral trait is that they are extremely tame. They have no fear of humans whatsoever. Charles Darwin noted this back in 1835; that if he threw a marine iguana into the water, it would return to land at the exact same place again. Tourists love this about Galapagos marine iguanas as it makes closeup photography a breeze.
Marine iguana diet
What do Galapagos marine iguanas eat? They are herbivores, feeding on a diet of green algae and seaweed. They usually dive for up to one minute at a time, with their heartbeat slowing to half its normal rate to conserve energy in the cold water.
Why is the Galapagos Marine Iguana endangered?
Today the marine iguana population at Galapagos numbers between 200,000 to 300,000 individuals. They are listed as Vulnerable and in decline by the IUCN Red List. But why is this?
Firstly, baby marine iguanas have a long list of predators. Hawks and snakes in particular hunt them in large numbers during hatching season. Invasive species like rats, cats and dogs are also a threat, feeding on marine iguana eggs and young. Galapagos conservation projects are ongoing to eradicate introduced species, and return habitats back to their original state.
The El Niño weather phenomenon is another big risk for Galapagos marine iguanas. El niño occurs every decade or so, affecting the whole coast of South America. It causes a small rise in sea temperatures, which in turn reduces the important nutrients found in the ocean. Fewer algae, plankton and nutrients means fewer fish, which also means hungry marine iguanas. Severe El Niño events mean that no hathlings survive, and also causes a huge dent in adult population numbers (70% loss in El Niño 1982/3). It takes many years afterwards for marine iguana colonies to recover.
Interesting Marine Iguana Facts
• A Marine Iguana sneezing salt is a funny sight at Galapagos. After swimming in the sea they need to expel sea salt from their bodies. So marine iguanas have special glands in their nose to filter out salt, and sneeze it out. Visitors can often see an accumulation of salt on top of their heads, encrusted in white as a result.
• There are a total of eleven different Marine Iguana subspecies at Galapagos. The largest marine iguanas live on San Cristobal island, measuring over one meter in length. Rather appropriately they have been named the Godzilla Marine Iguana (Amblyrhynchus Cristatus Godzilla).
• Galapagos marine iguanas vary in color between each island subspecies. The most colorful are the Christmas iguanas on Española Island, in wonderful bright red and green combinations. Genovesa has the smallest and blackest marine iguana. Fernandina and Northern Isabela have the largest marine iguanas, colored dull green and red. On Santa Cruz they are red and black. Marine iguana coloring also changes through the seasons, becoming brighter during mating season, before returning to black.
• In times of scarce food the Galapagos Marine Iguana has developed an ability that almost no other animal can do: it shrinks! Quite literally, bones become smaller and their skeleton retracts. This means that they can eat less without becoming malnourished. As soon as food returns they then grow back to their original size again.
Check out our seperate posts for more interesting Marine Iguana facts or to learn about more Galapagos Reptiles & Animals.
In conclusion, the Galapagos marine iguana is one of the most fascinating characters at the Galapagos islands. They are hugely photogenic for visitors when they huddle together in groups. They have an incredible story to tell, of evolution and adaptation against all the odds. They demonstrate unique and quirky behavior. Plus you never get tired of spotting them because they come in different colors and sizes on each island. We hope you enjoyed learning about Galapagos marine iguanas, now it's time to go meet them for yourself!
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