Many reptiles make their homes in the rivers and streams that drain the Earth's rainforests.

Most of these lie partially submerged beneath the river's surface, where they feed on fish, invertebrates or plants.

However, some, such as the anaconda, the largest snake on Earth, and the freshwater crocodiles, can present a danger to human beings.

The larger crocodiles and caimans will attack forest hogs and pacas when they come to the river for a drink.

The huge, powerful tails of caimans and crocodiles provide them with grace and precision of movement. The attacks made by these reptiles are usually successful.

Crocodiles seldom attack on dry land.

Several species of turtle can be found in the rivers of South America.

The arrau turtle, Podocnemis expansa, one of the largest turtles in the world, can weigh up to 130 pounds (60kg).