Pyxicephalus
Encyclopedia
Pyxicephalus is a genus of true frog
True frog
The true frogs, family Ranidae, have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on most continents except Antarctica...

s from Sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

, commonly referred to as African Bull Frogs. Also known as the Pixie frog, which was derived from its genus name. It is the largest frog in South Africa. It lives in open grasslands, can be found in puddles. In the dry season it burrows under ground. This frog eats insects of various kinds, fish, mice, lizards, and some times other frogs. If threatened the frog puffs up in an attempt to frighten the offender.

Physical Characteristics

The most obvious characteristic that differentiates Pyxicephalus adspersus from other frogs is its size; its one of the biggest, second only to the Rana goliath of the Congo basin
Congo Basin
The Congo Basin is the sedimentary basin that is the drainage of the Congo River of west equatorial Africa. The basin begins in the highlands of the East African Rift system with input from the Chambeshi River, the Uele and Ubangi Rivers in the upper reaches and the Lualaba River draining wetlands...

. Individuals can weigh up to 2 kilograms (4.4 lbs). Unlike most other species of frog, the P. adspersus male is larger than the female. The male can be up to 24 cm (9.5 in.) long and the females are about 12 cm (4.45 in.). Their skin color is a dull green; the males have yellow throats and the females throats are cream-colored. Juveniles differ in that they are bright green and have a yellow stripe down their back. This stripe fades away as they mature in about one and a half to two years. Also, older frogs have more obvious skin folds than the younger ones.

The body of the frog is very broad, with a short rounded snout, protruding jaw, and tooth-like projections in its lower jaw. It has a large mouth, sharp teeth and very little webbing on its feet. Another way that this bullfrog differs from other frogs is that it has very strong hind legs, which it uses to dig holes in ground, so that it can estivate
Estivation
Aestivation is a state of animal dormancy, characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions...

 during the dry season. It makes a dry, watertight cocoon for itself, which prevents the evaporation of body fluids; it loses approximately half of the water that a frog without a cocoon would lose. The frogs can actually survive for several months in dry soil by absorbing water stored in the bladder. Once the rainy season starts, the moisture will seep into the ground and soak the cocoon. Once it softens enough to split open, the frog eats it.

Distribution and Habitat

This type of frog is found mostly in open grasslands and at low elevations in the sub-Saharan African countries of Malawi
Malawi
The Republic of Malawi is a landlocked country in southeast Africa that was formerly known as Nyasaland. It is bordered by Zambia to the northwest, Tanzania to the northeast, and Mozambique on the east, south and west. The country is separated from Tanzania and Mozambique by Lake Malawi. Its size...

, Zambia
Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....

, Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

, Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...

, Mozambique
Mozambique
Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...

, Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...

, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 (except for the southwestern Cape Province
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...

), Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

, Zimbabwe
Zimbabwe
Zimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...

, Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

 and the Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...

.

Diet

The African bullfrog is carnivorous. It will feed on anything it can fit into its mouth, including insects, small rodents (such as mice), reptiles, birds, and amphibians (including other frogs).

Behavior

It is quite aggressive, and has been known to jump at things that it views to be a threat. Because of its sharp teeth, its bite can be quite serious. The male bullfrog will also aggressively defend his eggs if an animal or a human should approach. The males make calls only during the rainy season, which is when they come out of estivation to breed in pools of water. They tend to congregate around watering holes, including ones occupied by large animals like elephants. The call of Pyxicephalus adspersus is composed of loud, throaty bellows and deep grunts. These frogs can get rather territorial during mating and begin their mating calls only when they have established their territory. The African bullfrog can be quite lazy but will eat anything around it.

Reproduction and Growth

The African bullfrog lays about three thousand to four thousand eggs in shallow water. The tiny eggs are only about 2 mm, are black and white and are encased in a 4 mm jelly capsule. These eggs hatch about 2 days after being laid. The tadpoles are fat, heart-shaped, grey to black in color and their eyes are very close to together, situated on the top of their heads. About 18 days after hatching, the small frogs are 20 mm long and are able to leave the water to live on dry land. After this happens, these frogs have occasionally been known to eat each other. There is not a very good survival rate for these frogs; only about 20% of young adult females survive.

Conservation Status

Pyxicephalus adspersus is not listed among the world's endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

. Even though many indigenous peoples consider them to be a delicacy, their hunting has not had a significant effect on the size of the population.

Species

  • Pyxicephalus adspersus (Tschudi
    Johann Jakob von Tschudi
    Johann Jakob von Tschudi was a Swiss naturalist and explorer.Tschudi was born in Glarus, and studied natural sciences and medicine at the universities of Neuchâtel, Leiden and Paris. In 1838 he travelled to Peru, where he remained for five years exploring and collecting plants in the Andes...

    , 1838)
  • Pyxicephalus edulis (Peters
    Wilhelm Peters
    Wilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...

    , 1854)
  • Pyxicephalus obbianus (Calabresi
    Enrica Calabresi
    Enrica Calabresi was an Italian zoologist, herpetologist, and entomologist. Her family was part of the Jewish community which has played an important role in Ferrara, continuously since the Middle Ages....

    , 1927)

External links

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