Long-nosed chameleons like this one in Madagascar sometimes use their snouts to joust. Their noses also help similar species identify each other.

A remote camera catches the tail-end of a crocodile crawling into its den at Zakouma National Park in the central-African nation of Chad.

Jameson’s mambas, like this one in Mbanjong, Camroon, contain venom that may combat heart disease.

An agamid lizard sits above a muddy creek in the Danum Valley Conservation Area of Borneo Island, Malaysia.

A hawksbill sea turtle swims with a tracking tag on its flipper in the Little Bahama Bank of the Bahama Islands. Hawksbills get their name because of the sharp edges of their mouths.

A leaf-nosed crested lizard keeps its head up in the Danum Valley of Borneo Island, Malaysia.

A rare white alligator swims in New Orleans, Louisiana. The Audubon Aquarium of the Americas< estimates that less than 15 American alligators are leucistic, a condition that reduces their skin pigmentation.

The Galápagos tortoises of the Galapagos Islands are the largest tortoises on Earth. Some can grow to or exceed 5 feet (1.5 meters) in length and weigh as much as 550 pounds (250 kilograms).

A green turtle snake swallows a gecko in a rainforest.

This two-foot-long (0.6 metres) Oustalet’s chameleon in Allee des Baobab, Madagascar, is one of the larger kinds in the region. Other chameleons in the country are less than an inch long.