Leptodactylid Frogs: Leptodactylidae

Physical characteristics: Also known as the horned frog, Amazonian horned frog, or packman frog, the Surinam horned frog is a large, fat-looking frog. Its round, rather flat body has the shape of a doughnut without the hole. Its wide head has an immense mouth that stretches from one side to the other, light tan eyes, and pointy eyebrows that resemble little horns. The body, which has small, scattered, cone-shaped warts across the back and down the sides, is green to yellowish green. Its back is patterned with brown, blotchy stripes, and a thin, brown band runs across the head from one eyebrow horn The Surinam horned frog is an opportunistic hunter, which means that it will eat just about anything that it can grab and swallow. (Photograph from the Kansas University Natural History Museum. Reproduced by permission.) to the other. The frog usually sits with its rather small hind legs tucked up against the body and its short but thick front legs held pigeontoed, or facing inward. Both its front and hind legs are lime green with brown to dark green bands. The toes on the front feet are un-webbed, while those on the hind feet are partly webbed. The belly is smooth and cream-colored, and the throat is dark brown to black. Males and females look alike except during the mating season, when the males develop rough pads on the inner toe of each front foot. Adult females can grow to as much as 4.7 inches (12.0 centimeters) long from snout to rump. The males are smaller, reaching 3.1 inches (8.0 centimeters) in length.

Geographic range: The Surinam horned frog lives in the Amazon Basin, which is a large, low area of northern South America. In this region, heavy rains, small creeks, and streams all eventually drain into Amazon River. It also can be found in the small countries of French Guiana, Guyana, and Suriname.

Habitat: During most of the year, the horned frog stays on land and among the thick plants of the rainforest floor. In the breeding season, however, it moves into small pools of water, which may or may not dry up later in the season.

Diet: The Surinam horned frog is an opportunistic (ah-per-too-NIS-tik) hunter, which means that it will eat just about anything that it can grab and swallow. Prey includes grasshoppers and other insects, spiders, other frogs, and even quite large animals like snakes, lizards, and mice. The tadpoles, which have a long tooth-like poker on the bottom jaw, are also good hunters. They eat tadpoles, including other Surinam horned frog tadpoles, by opening their mouths and sucking them in. With a chomp of the jaws, the poker spears the prey, and the tadpole quickly swallows it.

Behavior and reproduction: Although it is a large frog, the Surinam horned frog can do quite a vanishing act. The ground of the rainforest is cluttered with growing plants and mounds of fallen leaves. This frog hops to such a mound, shuffles its body back and forth until all but its head is buried in the leaves, and then stops moving. With its pointy eyebrows that look like the edges of curled leaves and its camouflage colors, the frog nearly disappears. From here, it can watch for prey animals to walk unknowingly past. When one approaches closely enough, the frog lunges out, opens its immense mouth, and snaps it up. The frog may continue this style of sit-and-wait hunting, called ambush hunting, for several days from the same spot. It usually waits until dark on a rainy night to move to a new place.

Breeding season for this species is short, with all of the frogs mating and laying eggs when the first, heavy spring storms soak the land. The males hop to pools of water, sit on the edges, and make their deep calls. Some people describe the call as sounding like the "moo" of a cow or the "baa" of a sheep. When a female responds to a male's call, he climbs onto her back and hangs on by her front legs. The female lays up to 2,000 small eggs in the water. The eggs develop into tadpoles, which grow to about 2.5 inches (6.5 centimeters) long from head to tail before changing into froglets.

Surinam horned frogs and people: People see this frog more often in the pet store than in the wild.

Conservation status: The World Conservation Union (IUCN) does not consider this species to be at risk. Some of the areas where this frog lives are protected places, such as refuges and parks, but some are not. As more forests are logged and otherwise cleared, this frog's habitat is shrinking. ∎