- Status: Threatened, USFWS
- Endangered, IUCN
- Family: Ranidae (True frogs)
- Description: The world's largest frog.
- Habitat: Near rapids and waterfalls of tropical rivers and streams.
- Food: Smaller animals.
- Reproduction: Lays externally fertilized eggs in water.
- Threats: Habitat loss and hunting.
- Range: Cameroon and Equatorial Guinea.
The Goliath frog is a giant among amphibians and the largest frog in the world. Its maximum weight is nearly 8 pounds (3.6 kg) and the body length (with legs extended) is almost 30 inches (76 cm). It has a granular, greenish brown skin on the back, and is effectively camouflaged amid the wet moss-covered rocks on which it often sits. Its underparts are pale orange or yellow. The eyes can be nearly 1 inch (2.5 cm) in diameter. The sexes are similar in appearance. Its eggs are large, up to 0.3 inch (8 mm) in diameter (including the jellylike surrounding), and are attached to vegetation along streamsides or around the margin of pools among rocks. The tadpoles are not larger than those of other large frogs, so the enormous size of the adult frog reflects growth after the tadpole stage, which lasts for around 70 days. The feet of adults are extensively webbed, reflecting the aquatic habits of the species. The Goliath frog is more active during the night, when its searches for food along river and wetland margins.
The tadpoles graze on aquatic vegetation, and are able to cling to rocks in fast water using their sucker-like mouthparts. It is thought that the tadpoles feed exclusively on one particular plant during the first weeks of life, and this may limit the spread of the species. Adult frogs feed on a variety of prey, including insects, crustaceans, mollusks, other amphibians, and small mammals. Smaller adults spend most of their time in water, with perhaps just the snout emerging. Larger adults frequently come out to bask on moist rocks.
The Goliath frog has rather narrow habitat requirements. It occurs in humid tropical forest, in the vicinity of rapids and waterfalls of streams and rivers flowing to the coast. The presence of key larval food plants may further limit the species. Rivers investigated have clean, well-oxygenated, slightly acidic water. The average air temperature in a typical locality is 87°F (29°C), and the water temperature around 67°F (17°C).
The Goliath frog occurs in Central Africa, in a relatively small range about 150 mi (241 km) long by 55 mi (88 km) wide, near the coast in Cameroon and Equatorial Guinea (and possibly Gabon). Its range extends from the region of Nkongsamba in southwestern Cameroon south to Monte Alen in mainland Equatorial Guinea.
The Goliath frog is highly valued as food among local people, and excessive harvesting is the most important threat facing this species. There has been much concern about the collection of these huge frogs for the international pet and zoo trade, as large specimens have been on sale for several thousand dollars. In addition, the Goliath frog is at risk because of its highly restricted range and habitat requirements, which make it vulnerable to damming or pollution of its water-courses and to clearing of the surrounding forest.
Conservation and Recovery
Goliath frogs are not currently a protected species, and their international trade is not yet regulated or banned by CITES. There are almost no restrictions on the hunting or trade of this rare species. The species is known to occur in at least one protected area--Monte Alen National Park in Equatorial Guinea.