Main Characteristics

Marine Iguanas are between 50 and 100 cms (20 - 39 inches) in length and they weigh up to 10 kgs (22 lbs), although there is a vast size difference between the iguanas from different islands. The largest Marine Iguanas are found on Fernandina and Isabela Islands where as the smallest Marine Iguanas are found on Genovesa Island.

They are black or grey in colour but during the breeding season adult males develop red and green colouration and young Marine Iguanas have a lighter coloured dorsal stripe.

They have triangular shaped dorsal scales and a long tail that they use to propel them through the water while swimming. They are often encrusted in a white substance which is mainly excess salt that has been excreted from their nasal glands.

Marine Iguanas can lose up to 10°c of body heat during a dive into the sea, so after each dive they return to shore to bask in the sun and warm up. During this period they are unable to move effectively and can be highly aggressive towards any potential predators as they are unable to run away until their body temperature has risen.

Habitat

Marine Iguanas are found on the Galapagos Islands. When they are not foraging in the sea, they spend their time basking on rocks and often several thousand individuals can be seen together on the same stretch of shore.

Diet

Marine Iguanas mainly feed on marine algae. Larger Iguanas dive into the sea to forage and can dive down to depths of 12 m (39 ft) and stay submerged for over an hour, however, under normal conditions they make shallow dives that usually last around 10 minutes. Smaller Iguanas do not enter the water, instead they feed on algae from the rocks in the tidal zone.

Breeding

The breeding season begins in December and males develop red and green colouration, and fight aggressively for the opportunity to mate. Females move inland and lay 1 - 6 eggs in a sandy burrow. Thousands of females can be found nesting in the same area as suitable nesting sites are scarce.

Females will stay and defend their burrow for several days then they leave the eggs to incubate. After 2 - 3 months the young iguanas dig their way out of the nest and move to the intertidal zone to feed.

Predators

Predators of Marine Iguanas and their young include hawks, owls, rats, seabirds, cats and dogs.

Subspecies

There are seven subspecies of Marine Iguana that are found throughout the Galapagos Islands. They differ in size and colour depending on which island they are found on.

Amblyrhynchus cristatus albemarlensis
Amblyrhynchus cristatus cristatus
Amblyrhynchus cristatus hassi
Amblyrhynchus cristatus mertensi
Amblyrhynchus cristatus nanus
Amblyrhynchus cristatus sielmanni
Amblyrhynchus cristatus venustissimus

Interesting Facts

Marine Iguanas are also known as:
Galapagos Marine Iguana
Sea Iguana

Marine Iguanas are the only lizards that forage for food in the sea.

Similar Animals

Galapagos Land Iguana