The marine iguana is endemic to the Galapagos Islands. They are the only lizards who can swim and find food in the water. There are 11 different subspecies on the different islands. Male lizards change color from black to red or green during mating season, depending on the subspecies of marine iguana. Marine iguanas are very uncoordinated on land, but they are very fast in the water. Marine iguanas are excellent swimmers, and have claws to grab algae to eat from rocks. Smaller iguanas stay close to shore in small tidal pools, while larger iguanas swim further out to sea against the current. In water, the heartbeats of the marine iguanas are half of their normal heartbeats to conserve energy. Marine iguanas often bask in the sun and absorb heat to gain energy. Marine iguanas are very unique to the Galapagos Islands.