Conservation Status: Vulnerable
Scientific Name: Amblyrhynchus Cristatus
The Marine Iguana is one of the more curious creatures found at the Galapagos Islands – the only lizard in the world to have learnt how to swim, and dive into the ocean. These 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 refered to them as “most disgusting, clumsy lizards” as well as “Imps of darkness” during his voyage on the HMS Beagle.
So opinions are divided, but surely few can fail to be fascinated by their unique adaptations in physiology and diet. Marine Iguanas are believed to have descended from a mainland Land Iguana species, that most likely arrived to Galapagos by floating on logs or foliage in the currents. In their new volcanic habitat, they were forced to evolve the ability to swim in order to forage for food and survive, eventually transforming into the unique species we find today.
The Marine Iguana is most easily differentiated from it’s cousin, the Land Iguana, by colour. While Land Iguanas are yellow, Marine Iguanas are a shade of black or grey – necessary for these cold-blooded reptiles to to absorb sun and maintain warmth. During mating season they change colour, turning brilliant shades of red, orange, pink and green. Colour and size also vary across different islands, where different Marine Iguana subspecies are now recognised.
Where to Find Them: Throughout the islands, with especially large colonies on Isabela and Fernandina Islands.
When to See Them: Year Round. Mating season is typically from January to March.
The Galapagos Islands are the only place in the world where you can find a Marine Iguana – a Galapagos Land Trip is the perfect opportunity to observe them at close quarters, with Puerto Villamil Beach on Isabela, or Tortuga Bay on Santa Cruz being great spots.
Marine Iguanas live in large colonies, and are commonly sighted sunbathing together in groups, often lying one on top of another in photogenic poses. They huddle together to increase body temperature, before going for short excursions into the cold sea to feed.
Sandy shorelines close to black lava is very typical Marine Iguana habitat, where they like to live, mate and nest in burrows. During mating season dominant males fight for control of harems of females. Each female lays 2 or 3 eggs, which she buries in a burrow, and hatch 3-4 months later.
Various Marine Iguana adaptations were necessary in order to be able to swim (and therefore feed). Their respiratory system transformed to allow diving under water, sharp teeth evolved to saw food from the rocks, skin became darker for optimal absorption of sunlights, long claws developed to grip onto slippery rocks, tails became streamlined to steer expertly in the water, a flatter snout gives easier access to food, and their unique nostril glands allow them to desalinate after swimming. Quite a remarkable transformation!
What do Marine Iguanas eat? they are herbivores, feeding on a diet of green algae and seaweed. They use their strong tails to swim like crocodiles in the sea, and sharp teeth to chew algae from lava rocks. They can 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 Marine Iguana endangered? While total population numbers are between 200,000 to 300,000, the Marine Iguana does have various enemies. In particular introduced predators like rats, cats and dogs as well as native species like hawks and herons, feed on their eggs and young.
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