While we know that some reptile groups are particularly diverse, others occur in low densities compared to similar areas in the Asian tropics. For example, turtles, tortoises and venomous snakes are poorly represented when compared to many other humid tropical areas of the world.

Amazon reptiles occupy a very wide range of habitats (e.g. creeks, oxbows, rainforest canopy) and also show differences in their feeding habits.

Most reptiles, such as the boa, are carnivorous (they feed exclusively on other animals) while others, such as the green iguana, are primarily herbivorous (they eat mostly plant matter).¹

Boas²

Boas are collectively referred to as  boines  in South America, and they are without a doubt  the most famous snakes in the world. The widespread  boine  fauna of the Amazon River Basin and the Guianas includes five species, namely the boa constrictor (Boa constrictor), the emerald tree boa (Corallus caninus), the common tree boa (C. enydris), the rainbow boa (Epicrates cenchria) and the green anaconda (Eunectes murinus).

These species have overlapping distributions on the South American  mainland, and often occur with overlapping ranges.

To kill their prey,  boas  lie in wait until a suitable prey is in sight, wrap themselves around the victim and suffocate them. Prey may include fish, turtles, lizards, crocodiles, birds and even mammals, including deer.

Snakes need to swallow their prey whole. A large snake such as the boa can eat a 210 gr roof rat or a 9kg capybara. Different boa species use different habitats (e.g. trees, rivers), and by each specializing on different prey, they are able to co-exist with limited competition from each other.

Crocodiles and alligators (caimans)

Most active at night, these animals eat fish and other water dwelling animals, such as capybaras, birds and snakes.

True crocodilians and alligators/caimans look the same, but “crocs” have snouts that are more pointed than the “gators”. Crocodiles also have the upper fourth tooth visible when the jaws are closed. Alligators/caimans avoid saltwater. They are also more abundant.
 

Turtles

Turtles found in the Amazon River Basin belong to an ancient group called side-necked turtles. The head is tucked sideways rather than being hidden inside the shell. Only about 20 species are found.

The South American river turtle (Podocnemis expansa), also known as arrau and charapa, is the largest freshwater turtle in South America, with shells over 80 cm long reported for some females. Males are smaller and measure 40 cm on average.

These turtles have inhabited the earth for more than 158 million years and have a wide distribution. The species can be found in the Amazon and Orinoco river basins in Venezuela, Ecuador, Colombia, Peru, Bolivia, Brazil and Guyana.