The marine iguana is a unique species. It is thought that they are the ancestors of land iguanas that arrived to the Galapagos millions of years ago after floating from mainland South America on rafts of vegetation or debris. Some of the land iguanas that made their way to the Galapagos later gave rise to the marine iguana.
Marine iguanas feed on marine algae and they must swim in the cold waters surrounding the Galapagos to forage. Because these iguanas rely on the environment to maintain their body temperature, they must bask in the sun to heat up before diving. Their dark gray-black color helps them absorb sunlight quickly and thus warm their bodies.
The marine iguana's natural predators include hawks, snakes, short-eared owls, hawkfish and crabs and also faces threats from introduced predators such as cats, dogs, and rats (Roy 2000).