Ghost Frogs: Heleophrynidae

With colors and patterns that almost perfectly match the forest floor where they live, the ghost frogs live up to their name and, when they are very still, seem to vanish into the background. The Cape ghost frog, also known as Purcell's ghost frog, has a brown back and head that are covered with black blotches—almost as if someone had shaken out a wet paintbrush and splattered black paint on the frog. When in its habitat where the green mosses and plants and dark clumps of dirt and pebbles form a patterned blanket on the ground, the frog blends in well enough almost to disappear. People and predators can walk within a few feet of this frog and never notice it.

The other five species of ghost frog also have such camouflage, or cryptic (CRIP-tik) coloration. The frogs may be tan, brown, purplish brown, gray, or green, usually have darker blotches on the back and head, and may have dark bands around the front and back legs. The blotches may be purple, brown, or nearly black. The Natal ghost frog has the opposite coloration with a brown to black head and back and yellowish to green markings. The ghost frogs' undersides are typically lighter colored and almost see-through, giving them another ghost-like quality. Sometimes they have dark markings on the throat.

All ghost frogs have front and back toes that end in large, triangle-shaped pads. They have long, thin hind legs and shorter front legs on bodies that are slightly flattened. Their back toes are webbed, sometimes all the way to the tips. Their large, bulging eyes have catlike, vertical pupils, and their snouts are rounded in front and somewhat flattened overall. In their mouths, the tongue is disk-shaped, and small teeth line only the upper jaw.

Ghost frogs are small- to medium-sized frogs, reaching 1.4 to at least 2.6 inches (3.5 to 6.5 centimeters) long from the tip of the snout to the rump. Males and females look mostly alike, but the females usually are larger. Females of the largest species sometimes reach lengths a bit longer than 2.6 inches (6.5 centimeters). Males of the species called Rose's ghost frog also have small black spines on their lower front and rear legs, back, and thighs, and male Natal ghost frogs develop pads on the lower front legs and little spines on the toes of their front feet during breeding season.

The ghost frogs were once grouped in another family that includes the Surinam horned frog and other leptodactylid frogs, but they now have their own family. Although scientists believe that the ghost frogs are a very ancient group, they have not yet found any fossils of species in this family.