status: Vulnerable, IUCN Threatened, ESA
range: Cameroon, Equatorial Guinea
Description and biology
The Goliath frog is the largest frog in the world. It can weigh more than 7 pounds (3.2 kilograms) and measure almost 30 inches (76 centimeters) long with its legs extended. Its body alone can measure more than 12 inches (30.5 centimeters). The frog's upper body is greenish-brown in color, allowing it to blend well with the wet, moss-covered rocks on which it sits. Its underparts are pale orange or yellow. Its eyes can measure almost 1 inch (2.5 centimeters) in diameter. Males and females are very similar in appearance.
Adult Goliath frogs feed on insects, crustaceans, fish, and amphibians (such as newts, salamanders, and smaller frogs). Goliath tadpoles (immature or newly hatched frogs) eat only one particular plant found near waterfalls and rapids in their range. While smaller adults spend most of their time in water,
larger adults frequently come out to bask in sunlight on rocks. The frogs are more active during the night, when they search for food along river edges.
The Goliath frogs' eggs measure about 0.3 inch (0.8 centimeter) in diameter and are surrounded by a jellylike substance. After mating, a female Goliath frog lays her eggs attached to grass or other vegetation along streams or the margin of rocky pools. Upon hatching, Goliath tadpoles are no larger than tadpoles of other frog species. The tadpole stage, in which the young frog has external gills and a rounded body with a long tail bordered by fins, lasts about 70 days. The tail and gills disappear and legs develop by the end of this period.
Habitat and current distribution
The Goliath frog has a very small range. It inhabits only a strip of dense rain forest in coastal sections of Cameroon and Equatorial Guinea in Africa. This area measures about 150 miles (241 kilometers) long by 55 miles (88.5 kilometers) wide. Within this forest strip, the frog is found only among a few swift-moving rivers flowing to the coast. These rivers are clean and well-oxygenated, and have an average temperature of 65°F (18°C).
The total number of Goliath frogs in existence in the wild is unknown.
History and conservation measures
The Goliath frog was first identified in 1906. Since that time, private collectors have paid large sums of money to own a specimen. In America, an adult Goliath frog has sold for as much as $3,000. There are no restrictions on the international trade of these animals. Luckily, they are not easy to find, despite their large size. Currently, Goliath frogs are found in only two zoos in the United States.
The primary threat to Goliath frogs is the destruction of their limited habitat. Many areas of the rain forest have been cleared to create farmland. To supply water to newly created farms and villages throughout the region, dams have been built across many rivers inhabited by the frogs.
Finally, as human populations have increased in the Goliath frogs' range, so has the demand for them as a food source.