In the pages about the Galapagos islands, the word "endemic" is often used to describe a species that only occurs on these islands. Endemic animals or plants are restricted to a particular geographic region and found nowhere else in the world. Endemism usually occurs in areas that are isolated in some way. Since the Galapagos were never connected to the mainland which lies 960km away, all species had to reach the islands either by swimming (fish, sea lions etc.), by flying (birds, insects etc.) or on rafts (land animals, mammals, reptiles etc.). Once here they evolved and occupied different ecological niches. The endemic species in the Galapagos are specially adapted to the harsh conditions on the archipelago like the scarcity of fresh water, the availability of only certain food and the dark volcanic rocks.

Conditions for marine animals

Marine life in the Galapagos is very rich, though not so varied as in warmer tropical waters. Due to the cold water there are only a few species of corals and those grow mostly in the subtidal zone. There are nice reefs near Floreana (Devil's Crown, Onslow island), Bartolomé Island, Champion island and Wolf and Darwin.

In the warm season (from May to December), the chance to see whale sharks is very high (in the northern islands), and you can also observe them in the central islands. In the cold season (December to May) the chance to see whale sharks is about 50 percent, and you see more rays like mantas, mobula, and eagle rays, since they get together in schools to mate. Hammerheads can be found throughout the Galapagos Archipelago year-round. The large schools of fish, sea turtles, sea lions, iguanas and penguins are also found during the whole year