Amblyrhynchus cristatus    (Iguanidae)

 DISTRIBUTION: Found only on the Galápagos Islands. It has spread to all the islands in the archipelago.

HABITAT: has the ability, unique among modern lizards, to live and forage in the sea, making it a marine reptile. A. cristatus can dive over 30 ft (10 m) into the water. It mainly lives on the rocky Galapagos shore, but can also be spotted in marshes and mangrove beaches.

APPEARANCE: Not always black; the young have a lighter coloured dorsal stripe, and some adult specimens are grey. The iguanas living on the islands of Fernandina and Isabela are the largest found anywhere in the Galápagos. On the other end of the spectrum, the smallest iguanas are found on the island on Genovesa. Adult males are up to 1.7 metres (5.6 ft) long, females 0.6–1 metre (2.0–3.3 ft), males weigh up to 1.5 kilograms (3.3 lb). its laterally flattened tail and spiky dorsal fins allow it to swim further and faster, while its long, sharp claws allow it to hold onto rocks and other materials around it when there are strong currents so that it doesn’t drown or get lost/too far away from land.

DIET: The marine iguana feed almost exclusively on marine algae. Larger members of the species feed more often by diving at high tide while smaller animals are restricted to intertidal feeding at low tide.

REPRODUCTION: Males defend mating territories during the three-month annual breeding season. Females lay one to six eggs in burrows dug 30 to 80 cm deep. The eggs are laid in sand or volcanic ash up to 300m or more inland. Females guard the burrow for several days then leave the eggs to finish incubation, which is approximately 95 days. Nesting months are January through April depending on the island.

REMARKS:  As an ectothermic animal,  A. cristatus can spend only a limited time in the cold sea, where it dives for algae.  However, by swimming only in the shallow waters around the island they are able to survive single dives of up to half an hour at depths of more than 15 m.   After these dives, they return to their territory to bask in the sun and warm up again.

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