Thursday, November 8, 2012

Goliath Frog

The massive goliath frog (Conraua goliath), has greenish granular skin with a yellowish-orange underside, and the feet and hands are webbed. In a sample of 15 individuals, weights ranged between 600 grams and 3250 grams, and snout-vent lengths were between 17 and 32 cm. Their eyes can be nearly 2.5 cm in diameter. The conspicuous tympanum has a diameter of about 0.5 cm and is separated from the eye by about 5 cm in adults. The next largest extant anurans are the Cane toad, about a third smaller than the Goliath in the largest specimens, and the African bullfrog, which is just over half the size of the Goliath. Goliath frog eggs and tadpoles are about the same size as other frogs despite its very large adult form.

A lateral fold extends from the eye to the posterior portion of the tympanum. Toes are fully webbed, with large inter digital membranes extending down to the toe tips. The second toe is the longest. Dorsal coloration is green sienna, while the abdomen and ventral part of the limbs are yellow/orange. They have acute hearing but no vocal sac, and also lack nuptial pads.

 Did You Know
The goliath is the world's biggest frog with a body length of about one foot and weighing approximately 7 pounds! These frogs live in Western Africa along fast moving rivers that run through the rainforest.

Scientific Classification


Other Names

Goliath Frog
Grenouille Geante
Goliath Frosch

           The goliath frog is classified as Endangered (EN) on the IUCN Red List.

           The IUCN sites goliath frogs as an endangered species because of a 50% decline in population size in the last three generations. The population studies been carried out and will be published soon. (Expected to be 1000 adults).

It lives in or near fast-flowing rivers and streams in rainforest, preferring warmer, slower rivers than Conraua robusta, though faster rivers than C. crassipes. It can survive in secondary habitats close to rivers, as well as in forest, but not in very heavily degraded areas (farm bush). Breeding occurs in streams and small rivers. The young rest by flowing water during the day.

        The world's largest frog is known only from south-western Cameroon from the region of Nkongsamba, and south to Monte Alen in mainland Equatorial Guinea. It is generally found at low to medium altitudes, below 1,000m asl.

Like most amphibians, water is vital for their reproduction. Because the goliath frog lacks a vocal sac, it does not produce mating calls, a behavior unusually absent among frogs and toads. Males construct spawning and breeding areas alongside and within rivers by pushing rocks into semicircular patterns. The egg masses consist of several hundred eggs, approximately 3.5 mm each, attached to vegetation at the bottom of rivers. Larval development takes between 85 and 95 days. Goliath tadpoles are vegetarian and feed on a single aquatic plant, Dicraeia warmingii, found only near waterfalls and rapids, which may help explain their restricted range. Adult goliath frogs feed on worms, and insects, such as dragonflies and locusts. They also eat smaller frogs, crabs, baby turtles, and young snakes. The goliath frog can live up to 15 years in the wild. In captivity, they can live up to 21 years. It is preyed upon by snakes, Nile crocodiles, and Nile monitors.

Much of the dense rainforest of the goliath frog's habitat has been deforested for timber and to make way for agriculture. The construction of dams also threatens the breeding habitat of these frogs and this species is particularly vulnerable to habitat alteration due to its highly restricted range. Additionally, goliath frogs are considered a delicacy and are collected by local people for food; their large size has also encouraged collection for the pet trade in the past.

Conservation Measures
The goliath frog is not currently protected under any trade restrictions and collection continues to threaten remaining populations. Captive breeding programmes have not proven successful and the only method of effectively preserving this amphibious giant is to safeguard areas of remaining habitat. It presumably occurs in several protected areas, and is confirmed from Monte Alen National Park in Equatorial Guinea. Measures are needed to work with local communities to manage the harvest at sustainable levels.


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