Ranidae is one of the five families of frogs and toads that belong to the order Anura. Known as the true frogs, there are over 600 species of frogs found world wide that are part of this family. The remaining four families include Ascaphidae (the tailed frogs), Pelobatidae (the spade foots), Bufonidae (the true toads), and Hylidae (the tree frogs). Salamanders, mudpuppies, and newts, like frogs and toads, are also amphibians but are classified into their own order which is the order Caudata.
Because true frogs are found world wide, individual species may vary greatly from one to the next, but all members of Ranidae share specific characteristics not found in the other families. These characteristics include horizontal eye pupils, bony breast bones, teeth on the upper jaw, webbed hind feet, and an excellent jumping ability. Other characteristics include a slender waist, dorsolateral folds along their backs, long legs with pointed toes, and a strictly carnivorous diet. As with most organisms belonging to a large family, there will be exceptions as some species lack the dorsolateral folds or have bodies that are more on the stocky side.
Frogs belonging to the Ranidae family are also found in a huge range of sizes. The largest true frog is called the Goliath frog (Conraua goliath) which can measure 12.5 inches long from nose tip to rump and up 24 inches long or more when its legs are stretched out. Goliath frogs can weigh up to 7 pounds and easily dwarf the largest Bullfrog. This giant member of the Ranidae family is only found in fast moving streams and near waterfalls in the West African rainforests of Cameroon. Once widely sought after in the pet trade, Goliath frogs do not do well in captivity as they never seem to adjust to being away from their natural environment. Unlike other animals that grow large, the eggs and tadpoles of Goliath frogs are similarly sized to other smaller frog species. During its tadpole stage, the diet is exclusively vegetarian as the Goliath frog tadpoles feed off of water plants found growing in the fast moving streams that they subside in. As an adult, the Goliath frog is carnivorous and eats a variety of prey including fish, crustaceans, insects, small reptiles, and smaller amphibians including other frogs.
The smallest member of the Ranidae family is the Micro frog (Microbatrachella capensis) which is found in the moist woodlands of South Africa. The size of an adult Micro frog ranges from 0.4 to 0.7 inches from nose tip to rump. This tiny frog is on the critically endangered list as its environment is shrinking due to human encroachment and the introduction of non-native species of plants that use up the water that the Micro frog depends on for breeding.
Another well known member of the Ranidae family is the Bullfrog (Rana catesbeiana). Native to North America but introduced to many other locations world wide, the Bullfrog has all of the characteristics of a typical example of the Ranidae family. It has well webbed hind feet, horizontal pupils, and can jump to great heights and lengths. Its habitat includes ponds, lakes, and slow moving water where it hunts for its prey of insects, crustaceans, small reptiles, birds, small mammals, and even smaller Bullfrogs. Growing to a length of up to 8 inches long, the Bullfrog is North America’s largest species of frog.
The family Ranidae is a large and diverse family of frogs that contains the world’s largest and some of the world’s smallest species known to currently exist. The true frogs also come in a huge range of colors and can thrive in different types of habitats depending on their breeding habits and choice of prey.