Galapagos land iguana

Appearance

Charles Darwin described the Galapagos land iguana as "ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance." The Galapagos land iguana grows to a length of three to five feet with a body weight of up to twenty-five pounds, depending upon which island they are from. Being cold-blooded, they absorb heat from the sun by basking on volcanic rock, and at night sleep in burrows to conserve their body heat. These iguanas also enjoy a symbiotic relationship with birds; the birds remove parasites and ticks, providing relief to the iguanas and food for the birds.

Distribution

It is estimated that between 5,000 and 10,000 land iguanas are found in the Galapagos. These iguanas were so abundant on Santiago Island at one time that naturalist Charles Darwin remarked when it was called King James Island that "...when we were left at James, we could not for some time find a spot free from their burrows on which to pitch our single tent". In the years since then, entire populations have been wiped out by introduced feral animals such as pigs, rats, cats, and dogs.

It has been suggested that a pink morph of the Galapagos population is actually a genetically distinct subpopulation. This would warrant a separate species designation for the pink subpopulation. Subsequent genetic analysis of the pink morphs have suggested that the subpopulation split off from the main ''C. subcristatus'' one at least five million years ago.

Reproduction

Galapagos land iguanas become sexually mature anywhere between eight and fifteen years of age, depending on which island they are from. Mating season also varies between islands, but soon after mating, the females migrate to sandy areas to nest, laying 2–25 eggs in a burrow 18 inches deep. The eggs hatch anywhere from 90 to 125 days later.

On South Plaza Island, where the territories of marine iguanas and land iguanas overlap, the two sometimes interbreed, resulting in a mixture of features from each species; resulting in what is known as a hybrid iguana. The most likely unions tend to be between male marine iguanas and female land iguanas. Despite their long separation time and their being two distinct species from different genera, the offspring are viable, although likely sterile.

Food

Land iguanas are primarily herbivorous; however, some individuals have shown that they are opportunistic carnivores supplementing their diet with insects, centipedes and carrion. Because fresh water is scarce on the islands it inhabits, the Galapagos land iguana obtains the majority of its moisture from the prickly-pear cactus that makes up 80% of its diet: fruit, flowers, pads, and even spines. During the rainy season it will drink from available standing pools of water and feast on yellow flowers of the genus ''Portulaca''.

It is estimated that the Galapagos land iguana has a 50 to 60-year lifespan.