Squeakers and Cricket Frogs: Arthroleptidae

The squeakers and cricket frogs have smooth skin without the large warts seen in toads and many other types of frogs. A few, like the Ugandan squeaker, have some warts, but the warts are so small that they almost look like grains of sand. Depending on the species, some of the members of this family are reddish, greenish brown, brown, or almost black. Their toes have no webs between them, but the toes in some species end in large pads. Most have thin front and back legs. A few are burrowers, though, and have heavier legs to help them dig. Some of the burrowers also have thick, shovel-like bumps, or tubercles (TOO-ber-kulz), on the heels of their hind feet, which are also used in digging. Many species in this family grow to less than 1 inch (2.5 centimeters) long from the tip of the snout to the end of the rump, but some can grow much bigger. In many species, the adult's size is enough to tell a male from a female. In some, like the crowned forest frog, the male is much larger than the female, but in others, like the common squeaker, the female is bigger than the male.

Squeakers and cricket frogs are usually split into two groups, called subfamilies, although some scientists think the two subfamilies are so different that they should instead each have their own family. Others think the squeakers and cricket frogs should not have their own family at all and should instead be combined into the large family of true frogs, known as Ranidae. Many people disagree with this idea because of the breastbone. The breastbone, or sternum, is made of bone in the true frogs, but is different in the squeakers and cricket frogs. The sternum in squeakers and cricket frogs has some flexible material, called cartilage (CAR-tih-lej), in it. In this volume the squeakers and cricket frogs are all listed together in one family, separate from the true frogs. Inside this family are two subfamilies.

The larger of the two subfamilies is called Arthroleptinae and contains about two-thirds of the 77 species in the entire family. This group includes such species as the common squeaker, Tanner's litter frog, the Bush squeaker, and the Ugandan squeaker. Some of the features that most of these frogs share are a thin crease or ridge of skin that runs down the middle of the back and a dark pattern on the back that may be a row of diamonds, an hourglass, or something similar. The back of Tanner's litter frog, for instance, has a row of V-shaped markings. These patterns may be difficult to see on very dark-colored frogs.

The adult males also have a very long third toe on each of their front feet. Toes are counted from the inside to the outside, or from the big toe to the little toe, if compared to humans. This third toe on the West African screeching frog is as long as its thigh. In some species, the toe may be almost half as long as the frog's entire body. Many of the frogs in this subfamily, which as a group are called arthroleptins, have no teeth. Most of these frogs are small, but the female Tanner's litter frog grows to 2.4 inches (6 centimeters) in length, sometimes longer.

The second subfamily is called Astylosterninae and contains species like the crowned forest frog and the hairy frog, among others. Most of the frogs in this group have large bodies. The male crowned forest frog, for instance, grows to 2.7 inches long, and the male hairy frog can reach 5.2 inches in length. In both of these species, the males are bigger than the females. Members of this subfamily also have sharp, curved bones at the ends of their front toes. These bones poke out of the flesh at the tips of the toes, and sometimes look like claws. The front toes are also usually bent. All of these frogs have teeth on the upper jaw.