Galapagos Iguanas

Iguana is the common name for a large "New World" lizard. "Iguana" a Spanish word of Indian origin also serves as the scientific name for the family. Iguanas are diurnal. They have distinctive eyelids, external eardrums, dewlaps (throat pouches), each limb has 5 toes with sharp claws allowing them to climb. Unlike most lizards, Iguanas are vegetarians.

The Galapagos Islands are home to Marine Iguanas, Land Iguanas and a Hybrid mix of the whose father's are Marine Iguanas and mother's are Land Iguanas.

Marine Iguana (Amblyrhynchus Cristatus)

Growing to approximately 3 ft (1 m) in length these sea-going Iguanas exist only in the Galapagos Islands. Living on the black lava shore rocks they have developed into efficient swimmers feeding off shore mostly on marine algae and seaweed.

The cold waters of the Galapagos provide both the necessary food for the Marine Iguanas and its most deadly threats. The cold temperatures can immobilize an iguana if it remains in the water too long. Until the arrival of man, Marine Iguanas only threats were that of larger fish and sharks encountered while swimming.

When Marine Iguanas are not feeding they seek safety and warmth of the land. In the 19th century when Charles Darwin visited the islands he found thousands of Marine Iguanas living along the rocky shore. He picked one up and threw it into the ocean it instantly swam back to the shore. This was repeated several times and the Iguana continued to seek the safety of the shore when it could have easily swum off to escape Darwin.

The black rocks under the equatorial sun provide needed warmth for the iguanas. On a warm day these rocks can heat up to deadly temperatures. Yet, territorial male Marine Iguanas, remain in the sun during the day. Cooled by a circulatory heat shunt carrying heat from the back to their bellies where the sea breezes coming off the cool ocean waters can cool them by convection. At night the iguanas pile by the hundred in order to provide heat for one another.

Galapagos Land Iguana (Conolophus Subcristatus)

Land Iguanas grow to a bulky girth and 3 ft (1 m) in length. Their yellowish-orange belly and brownish red back make them more colorful then their cousins the Marine Iguana. The Land Iguanas live in the arid portion of the islands.

The mainstay of its diet is the Prickly Pear Cactus. They eat the pads and fruit including the spines. The cactus provides both food and water for the Land Iguanas can go without fresh water for a year. Part of the adaptation to the drier environment includes a conservation of energy by slow movement. This makes the animals seem lazy or stupid. Land Iguanas burrow into the ground creating tunnels which provides a place for nesting, shade during the day and protection at night.