African bullfrog

800px-Pyxicephalus_adspersus,_Boston_Aquarium

Profile

African bullfrogs are large frogs living in central Africa. Both males and females are olive green in color on their back, but their throats are different from their backs and from each other. The males have a yellow or orange neck, while the females have a cream or light brown throat. Because of this, you can tell that the African bullfrog pictured above is a female. The frog’s belly is about the same color as its throat. Their coloring helps these frogs stay hidden from not only potential predators but also prey. This helps them be undetected as they ambush their next meal.

These frogs have very large and powerful hind legs, which help them jump far and dig burrows. African bullfrogs also have large metatarsal tubercles, a part of their foot that help them dig better. Both the males and the females have ridges on their back. You can see some of these in the picture above. They run from front to back, but they don’t usually go all the way from front to back. On the lower jaw, these frogs have a set of three spike-shaped teeth. They have two uses which I will talk about later. Another name for this frog is the pixie frog, not given because they look like fairies. Instead, this name comes from their scientific genus Pyxicephalus.

Size

African bullfrogs are rather large for frogs, however they are not the largest frogs. That title belonging to the goliath frog, which also lives in Africa. The males especially can be very large, reaching up to 9 inches (23 cm) long, and weighing up to 4.5 pounds (2 kg). Females are usually about half this size, and most males are smaller than these measurements also.

Diet and hunting

African bullfrogs are not picky at all when it comes to food. They will consume almost any animal that will fit in their mouth. Their prey includes insects, fish, mice, small birds, lizards, and even other frogs. The young tadpoles are cannibalistic, as their first meal usually consists of frog eggs or other tadpoles. Because they are so big, African bullfrogs can overpower most small animals. When hunting, these frogs curl their tongue up in their mouth. When their prey is within striking distance, they quickly drop their lower jaw, forcing their tongue out at a high speed. This hits the unsuspecting victim; the stickiness holds it, and the frog then brings it back into its mouth. This is where one of the uses of the three teeth comes in to play. Struggling prey is restrained by the teeth until the frog can kill it.

Status and threats

The IUCN Redlist has classified this frog as Least Concern, but its population is decreasing. There are a few natural predators of the African bullfrog, even though they are so large. These enemies include turtles and monitor lizards, which prey on the young, and large birds, which can eat adults. Habitat loss is a minor threat, and the worst threat humans give these frogs is harvesting them to eat.

Habitat and range

African bullfrogs typically live in central Africa. They do not live in the North where the Sahara Desert is, and they are not as common in the far south. Although they do not prefer desert areas, these frogs live in almost any habitat, including extremely dry areas. African bullfrogs are considered to be one of the most adaptable amphibians on earth. They can survive temperatures as high as one hundred degrees Fahrenheit (38 C) as well as temperatures below freezing! They do hibernate during this time, however.

Hibernation

Unlike most other animals that hibernate, African bullfrogs do not hibernate in the winter, as Africa doesn’t usually get very cold. Instead they hibernate during the dry season as African lungfish do. They also have a similar hibernation technique. When the rain begins to come less frequently, they will burrow into the mud and form a cocoon of mucous around themselves. The mud and the cocoon dry, and as the cocoon dries it hardens, forming a protective barrier. When the rains eventually come again, the cocoon and the mud soften letting the frog wake up and crawl out of the ground. They can survive hibernating for up to two years at once! When the African bullfrogs wake up, they begin their mating season. Click here to watch a video about their hibernation and mating rituals.

Reproduction

Male African bullfrogs are extremely aggressive when it comes to mating. They fight each other for the right to mate, and their fights do not always end well. They will attack each other, jump on each other, and even bite each other, another use for their three conical teeth. Some large males will even eat smaller ones! Large males push their way to the center of a group with the smaller males around the outside, and the males then begin to call. The females hear the call and come to the group. They then swim under the outside of the group, which is formed in a pool of water, and surface in the middle where all the larger males are. African bullfrogs are ready to mate by three years of age.

Once a female chooses a male, she will mate in shallow waters where the pair doesn’t need to swim to stay afloat. The female lays up to 4,000 eggs while mating. The male is the parent that watches over the eggs, which he does for the two days before they hatch. After they hatch, the tadpoles eat small fish and invertebrates as well as each other. Sometimes the small part of the pool where the eggs are laid starts to dry up. At this time, the male, who is still caring for the young, will dig a channel from the small part to the main body of the pool. This releases the tadpoles into a larger area that has more predators but also more water. The tadpoles take up to three weeks to fully metamorphose into their adult from. Although the male is meant to protect the young he sometimes forgets his purpose. If he gets a little hungry the tadpoles can become too tempting and become his next meal. If the tadpoles survive this and their other predators, they can live up to twenty-five years.

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Iguana_marina_(Amblyrhynchus_cristatus),_Las_Bachas,_isla_Baltra,_islas_Galápagos,_Ecuador,_2015-07-23,_DD_23

Sources:

Photo credits:

  • African Bullfrog – Steven G. Johnson
  • Mystery animal – Diego Delso
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