Conolophus subcristatus (Gray, 1831)

Initial Species Description

Charles Darwin, who observed Galápagos land iguana (Conolophus subcristatus), described the species as ugly animals yellowish-orange on the underside and brownish-red above, with a singularly stupid appearance from their low facial angle.

Size and Weight

This species is one of the largest lizards in the world, growing 0.9 to 1.5 m (3–5 ft) long and reaching a maximum body weight of 13 kg (29 lb), with size varying by the island a individual comes from.

Thermoregulation

As cold-blooded animals, Galápagos land iguanas raise their body temperature by basking on volcanic rock and other dark-colored stones that naturally absorb solar heat. At night, they sleep in burrows to conserve the body heat they have absorbed.

Symbiotic Relationship

These iguanas share a symbiotic relationship with birds: the birds remove parasites like ticks from the iguanas, giving the iguanas relief while providing the birds with food.

Sexual Maturity

Galápagos land iguanas reach sexual maturity between eight and fifteen years of age, with the age of maturity varying by island.

Mating Season

Mating season also differs between islands.

Nesting Behavior

Shortly after mating, females migrate to sandy areas to nest, laying between 2 and 20 eggs in a burrow approximately 50 cm (20 in) deep.

Incubation Period

The eggs hatch between 90 and 125 days after laying.

Interspecies Hybridization

On South Plaza Island, the territories of marine iguanas and Galápagos land iguanas overlap, and the two species sometimes interbreed to produce hybrid iguanas that show a mix of features from both parent species. Most interbreeding occurs between male marine iguanas and female land iguanas.

Hybrid Viability

In spite of the long separation between the two lineages, and that these are distinct species belonging to different genera, hybrid offspring are viable, though they are most likely sterile.