Galapagos – Animal Expedition – Iguanas and Lizards
When Charles Darwin visited the Galápagos Islands, some areas were teeming with iguanas that he had difficulty setting up his tent. Today they are only numerous on Fernandina. On Santiago, for example, they were completely exterminated by introduced rats and feral pigs. During the mating season, the males engage in fierce fights, which usually end bloodlessly. If the opponent takes a position of humility, the winner lets him pull off generously.
There are 14 subspecies of the lava lizard, with the Espanola species being endemic. They grow up to 30 cm long here. The female lava lizard is smaller and has a bright red spot on her throat. Males and females have their own territories that must be defended, with only same-sex invaders being fought.
Land iguanas live singly, in pairs or in small groups. They can grow up to 1.20 m long. They look like they are from another time.
Prickly cactus leaves suit them just as well as tender green plant leaves. They take the vital moisture from the thick cactus leaves, because fresh water is lacking on many islands. The fruits are a treat. Since they are quite prickly, the iguanas roll them over the stones until the last sting has broken off.
A male that distinguishes itself from others by its striking colors has a greater chance of choosing a partner and thus more offspring. During mating season, the males fight for the best and largest territories, because the females only like strong supermales. This ensures that only the strongest can reproduce. However, the fights are more ceremonial in nature, the animals do not hurt each other. The fight is initiated by a vigorous nod of the head, the rivals stand erect opposite each other. They collide with their foreheads and try to push each other off the pitch. The weaker one gives in and goes his way. The situation is different with the females: they have to dig deep holes in the earth to lay their eggs there.
Loose soils are therefore very popular and where these places are rare, they often fight each other to the death. Only the strongest of them can reproduce.
Marine iguanas are cold-blooded animals, their body temperature rises and falls with the ambient temperature. When the tide comes and they have recharged enough energy on land, they go in search of food on the seabed, where they graze on algae carpets. No other lizard in the world feeds on the sea, and they are one of the few animals that can drink seawater. They have glands in the nasal region with which they excrete the excess salt.
