Among about 6,000 species of frogs, salamanders and caecilians (legless animals, pronounced like "Sicilians") are some of the world's most bizarre animals: Giant Chinese salamanders, two meters (6 feet) in length; the "hairy frog" of Cameroon, which not only looks like it sports hair, but also can break its own bones to grow claws (an ability discovered just last month); the Surinam toad, which carries its eggs embedded in its back; and, even more macabre, the Sagalla caecilian, which feeds its own skin to its young.

Amphibians are also among the most colorful animals: The tiny, bright-yellow poison frog (with the spectacular scientific name Phyllobates terriblis) from Colombia, which is, gram for gram, the most poisonous vertebrate in the world; the black-dotted yellow frogs of Panama, which communicate with adorable hand waves; and the charismatic red-eyed tree frogs, aptly nicknamed "swimsuit calendar frogs."

These make up just a small sample of the amazingly diverse amphibians, which have the longest history on earth. They predate all other terrestrial vertebrates.

Yet the first group of animals to colonize the land is also the first that humans are driving off it. Amphibians are disappearing faster than any other animals since the dinosaurs: 32 per cent of all species are threatened with extinction, compared with 23 per cent of mammals and 12 per cent of birds. Almost half are in decline.