‚ÄčGalapagos Marine Iguana (Amblyrhynchus Cristatus)
Galapagos Marine Iguana (Amblyrhynchus Cristatus) downloaded 10/5/09

Location and Habitat:
The Galapagos Marine Iguana live on the Galapagos Islands- volcanic islands that form an archipelago off the coast of South America. The marine iguana lives in areas where there is a large intertidal zone (space between low tide line and high tide line) and rocky coastlines. The islands have never been attached to a land mass, so it is thought that they rafted over water from South America 10 to 15 million years ago. They bask in the sun on low cliffs 2-5 meters above sea level, but may climb as high as 80 meters. The iguanas also need access to sandy areas, where they bury their eggs.
Location of Marine Iguana downloaded 10/6/09

The Galapagos Marine Iguana is the only species of marine lizard in the world, and one of the few species of the Galapagos that can be found on all of the islands. They are small, about .75 meters (2.46 feet) in length, and black in color, and are usually regarded as being extremely ugly. They have adapted to their environment, evolving blunt noses to eat seaweed, flattened tails to assist swimming, and strong claws to cling to rocks. The iguanas feed mainly on seaweed in the intertidal zone, although larger individuals will swim out to feed underwater. The waters around the islands are cold, and being exothermic, they can usually only spend a short period of time in the water. After feeding, they will spend time laying on rocks in the sun to regain body heat. As a species, the Marine Iguana breeds every year for a period of 3 months, starting around December on most of the islands. Individual iguanas breed once every 2 years. Females lay between 1 and 6 eggs in burrows up to 300 meters inland, and between 30 and 80 centimeters deep. The females will guard the burrows for several days, then leave them to finish incubation which takes about 95 days. After hatching, the young look and act like miniature adults, and recieve no parental care.
Marine Iguanas are diurnal and spend several hours after sunrise basking in the sun to prepare for activity. They become less active between noon and evening, and retreat into crevices or underneath boulders before sunset. Marine Iguanas live in colonies for most of the year, but become territorial during the breading season.
The biggest threats to the Marine Iguanas come from hawks, and introduced specied such as dogs, cats, and rats. They have adapted some anti-predator behaviors towards the hawks, however, the wild dogs, cats, and rats feed on eggs and young hatchlings. The iguanas are very tame, and will lay out in the sun, even though there are predators that will attack them. They also have a very small flight distance, because a lot of movement will cost them a lot of energy. The environmental changes caused by El Nino can cause the availability of certain foods the Marine Iguanas eat to decline, and damage their population.
Marine Iguana at the entrance of a burrow downloaded 10/6/09

Population Expansion
The Marine Iguana could easily fill the niche of the Land Iguana if it were to go extinct. The animals that prey on the Land Iguana- hawks, dogs, cats, and rats- can also prey on the marine iguana. Both species of iguana live in similar crevices, and dig burrows to store their eggs. The Marine Iguana feeds primarily on seaweeds, so it is not known if they could eat the cactus fruit that the Land Iguana eats.

Species in Competition
It is estimated that there are between 5,000-10,000 Land Iguanas, and around 50,000 Marine Iguanas. However, the El Nino effects cause periodic declines in the Marine Iguana population. In general, the Marine Iguana should be able to take over the Land Iguana's niche fairly quickly, as predators would most likely go directly after the Marine Iguana if the Land Iguanas were gone.

Works Cited
//All About Marine Iguanas//. (n.d.). Retrieved October 15, 2009, from http://www.associatedcontent.com/
//Galapagos Marine Iguana//. (n.d.). Retrieved October 15, 2009, from http://www.arkive.org/