The Marine Iguanas of the Galapagos Islands

Charles Darwin's study of wildlife in the Galapagos Islands opened the world's eyes to an exotic array of wildlife that had never been seen before. Many of its inhabitants are endemic, including the Galapagos giant tortoise, penguin, hawk, sea lion, and shark, to name a few. But perhaps the most compelling of its natives are the marine iguanas of the Galapagos Islands.

Like most lizards, the marine iguanas of the Galapagos are covered in scales. A row of spikes along the spine combined with long claws and whip-like tails makes this reptile seem like a fearsome predator, but any interest they show in humans is out of mere curiosity.

In fact, no warm or cold blooded creature need fear the marine iguanas of the Galapagos, for despite their rough exterior, they are vegetarians. They primarily feed on red and green algae occurring in the subtidal zone, but will very rarely feed on insects and crustaceans if their food sources are sparse.

There are 11 subspecies of marine iguana distributed among the Galapagos Islands, each of which have distinguishing characteristics that correspond to their location. They typically live in colonies, but territorial disputes tend to arise during the three-month breeding season.

Because they spend a great deal of time diving underwater to feed, the marine iguanas of the Galapagos have adapted their behavior to aid in thermoregulation. As cold-blooded creatures, they cannot generate their own body heat. Instead, they cluster together at night to sleep in order to conserve precious heat, and time their expeditions according to water temperature so as not to endanger themselves.

Their dark coloration also increases heat re-absorption as they bask on rocks under the tropical sun.

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Image via VSmithUK