Animal Case Profile: Marine Iguana

By CherryFranklin, 23rd Feb 2012 | Follow this author | RSS Feed | Short URL http://nut.bz/xgpwipb6/
Posted in Wikinut>Guides>Nature>Reptiles

This lizard can stay submerged underwater for over half an hour and one of the many animals discovered by Charles Darwin, the marine Iguana.

Quick Facts
Taxonomy
Appearance
Habitat & Distribution
Diet
Behaviour
Reproduction
Threats
Conservation
Facts

Quick Facts

Marine Iguana

Name: Marine Iguana
Latin: Amblyrhynchus cristatus
Classification: Reptile
Origin: Galapagos Islands
Lifespan: 5-12 yeas

Image copyright to wikipedia.com

Taxonomy

Kingdom: Animalia (Animals)
Phylum: Chordata (Vertebrates)
Class: Sauropsida (Reptiles)
Order: Squamata (Scaled Reptiles)
Family: Iguanadie (Iguanas)
Genus: Amblyrhynchus (Marine Iguana)
Species: Amblyrhynchus cristatus (Marine Iguana)

Appearance

Length: 4-5ft (1.2-1.5m)
Weight: 1-3.3lbs (0.5-1.5kg)

The marine iguana is dull black or dark grey in colour as to camouflage in with the seaside rocks it loves to bask on. It’s cold-blooded (or ectothermic) and uses its whip-like tail for swimming. It has wide set eyes, a flat face, spiky dorsal scales and a knotty, salt-encrusted face.
Charles Darwin described the creature as ‘hideous-looking’ and ‘most disgusting, clumsy lizard’ when he encountered the reptile.

Habitat & Distribution

The marine iguanas are found only on the Galapagos Islands and nowhere else on the Earth. They live on the western islands of the archipelago. This is where the water is coldest, but is also home to the species of seaweed that they eat.

Diet

The marine iguana eats certain species of red or green algae which grows close to the rocks that they bask on. Its mouth is rounded as to let it eat the seaweed easier. The marine iguana can stay underwater for a miraculously long time for a lizard. Charles Darwin conducted an experiment to see just how long they could. He submerged a large male in a bucket of seawater for over an hour, and the lizard seemed fine when released.
Females and smaller individuals feed close to the surf and at low tide at any time of day, and rarely is ever feed underwater. Large males wait until the middle of the day to feed. They spend the entire morning warming on the rocks to prepare themselves for the cold waters. An iguana can lose up to 10’C of heat during a dive, so after feeding it swims back up to the rocks and basks in the sun again.
Young sea lions like to hassle the iguanas while they are feeding by nudging them and pulling their tails, only to be ignored by the reptiles.

Behaviour

Marine iguanas are ‘cold-blooded’ meaning that they cannot regulate their body temperature like mammals and birds, instead they rely on the external environment i.e. the sun and the black rocks, which absorb the heat from the sun. The constantly bask in the sun to warm up in the morning and after a dive, and they move to the shade to cool down.
On a particularly cold morning, the iguanas have to wait for the midday sun to warm up enough for a dive. On hot days, the iguanas will cover each other for shade. At night they gather in large numbers to conserve body heat.

Reproduction

During the mating season, Male marine iguanas will develop red patches all over their scales, the extent of which varies from island to island. The males from Hood Island sometimes turn completely red during this season. Like many other animals, the male iguanas will butt heads to determine dominance and superiority, sometimes drawing blood.
Females will dig burrows in the soft sand in which their eggs are laid. A female can lie from 1 to 4 eggs and they take about four months to incubate. The young hatch at 3 to 4 inches long and are vulnerable to animals such as hawks, owls, herons and mockingbirds. When fully grown, their only real predator is the Galapagos Hawk.

Threats

Natural predators of the marine iguana can pose a threat to their survival. Wild animals such as hawks, owls, herons, mockingbirds and especially the Galapagos hawk eat the eggs and young of this reptile. Also, introduced feral animals, like cats, rats and dogs, steal and eat the marine iguanas eggs.
Being a cold-blooded animal, environmental fluctuations can be extremely harmful to the marine iguana, such as the ones cased by El Nino. The failing of trading winds causes an increase of sea temperature (4.3’C), an increase in sea levels and increased precipitation. El Nino occurs every 12.3 years. It causes an invasion of alga that takes over the normal food species of the iguana. Sometimes, as much as 50% of the marine iguana population can be wiped out during an El Nino.
Oil spills and marine pollution are a big threat to the marine iguana’s survival as they destroy food reserves and nesting beaches. In January 2001, millions of litres of oil was spilled in the waters of the Galapagos Islands by a Ecuadorian tanker. Then, during the following year, around 15,000 marine iguanas on the island of Santa Fe died (60% of the population there). Scientists believe that the oil killed the bacteria needed for the iguanas to digest the algae, making it impossible for them to absorb nutrients.

Conservation

Conservation Status: Vulnerable

Thanks to their biodiversity, the Galapagos Islands have long since been studied and protected. In March 1998, a 133,000km2 area was designated to be the Galapagos Marine Reserve (GMR), one of the world’s largest protected areas.
The conduct detailed conservation and research programmes which studies the islands ecology and the effects of environmental fluctuations. This includes the study of the species that live on the islands and also the effects of humans on the native wildlife. The GMR also tackles the problem of introduced feral animals.

Facts

Male: Bull
Female: Cow
Young: Hatchling

•Marine iguanas sneeze frequently to get rid of salt from glands near their noses.
•They live only on the Galapagos Islands and can be found no where else on Earth.
•If a marine iguana remains in the water too long, the cold temperatures could immobilize it.

Meet the author

CherryFranklin
I'm a 20 year old student studying animal management at college, so most of my writing will most likely be about animals. However, I also like to read and watch moviesso I may write some book and movie reviews, and I love Folkestone, the town where I...(more)