Narrow-Mouthed Frogs: Microhylidae

Most narrow-mouthed frogs eat only small invertebrates (in-VER-teh-brehts), which are insects and other animals without backbones. Many species have small mouths that come to a point at the end and can only eat tiny invertebrates. Ants are a favorite food for these frogs, but they will also eat other insects that are small enough to fit in their mouths. The Bolivian bleating frog is one of many species that are especially fond of ants. Other narrow-mouthed frogs have slightly larger mouths and are able to eat larger invertebrates. The New Guinea bush frog has a large head and especially wide mouth, which allows it to eat insects, as well as larger animals, like other frogs and lizards.

Scientists have not seen most of the frogs feeding, so they have to guess about how they go about eating. Some of the frogs probably eat insects that they find while they move about in trees or along the ground, but scientists think that many of these frogs may hunt by ambush. In this type of hunting, the frog sits very still. An insect that does not notice the frog may approach closely enough for the frog to grasp it and eat it.

Not all narrow-mouthed frog species have a tadpole stage, but in those that do, the tadpoles suck in water, sift out tiny microorganisms, and eat them. Microorganisms (MY-crow-OR-gan-izms) are living things that are too small to see. Scientists call this type of eating filter feeding, because the tadpoles sift, or filter, their food from the water. Some of the tadpoles have funnel-shaped mouths that are perfectly designed for filtering food from the surface of the water.