Amazon Horned Frog

The first thing that stands out about the Amazon horned frog is its size. These rotund amphibians can grow to 8 inches (20 centimeters) in length and would cover a good-size tea saucer. They are found in freshwater marshes and pools throughout the Amazon Basin, from Colombia to Brazil.

Amazon horned frogs achieve their enormous girth by being generally indiscriminate about what they eat. Typical ambush predators, they squeeze their bodies into the forest substrate or leaf litter so only their heads protrude. When anything smaller than their own bodies happens by, they spring from the mud and swallow their prey whole, locking it in their jaws with their sharp teeth.

They are aggressively territorial and voracious to a fault. Some have been found dead in the wild with the remains of an impossible-to-ingest victim still protruding from their mouths. Their ravenous appetite and huge mouths have earned them and other horned frogs the pet-trade nickname "Pac Man frogs."

Females are generally larger than males, but males are more ornately colored, ranging from dark green to lime-colored. Females are usually tan. Scientists are unsure what purpose their namesake horns serve, but it is likely they aid in camouflage, resembling leaf stems in the wild.