African Clawed Frog (Xenopus laevis)
Perhaps the most well known frogs from scientific experiments and biology dissection, the African Clawed Frog is actually quite unusual. Many of the regular organs and functions of frogs are modified in the African Clawed Frog.
For starters, the frogs do not have a tongue or visible ears. They use a throat pump to suck in food. Males do not have a vocal sac. They use their throat muscles to produce a clicking noise. It is the females of the species that makes an answering call. She can make two different kinds of answering calls; one for rejection and one for acceptance.
The African Clawed Frog does not have three eyelids like most frogs. In fact, they do not have any. A transparent film covers the eye and it does not blink.
Most frogs are known for their extraordinary hopping ability. Not the African Clawed frog, they dont even hop at all. They crawl.
Mottled a dark or light color, African Clawed frogs are color morphs and can make subtle changes in their camouflage. The front limbs have fingers while the hind legs have claws on the innermost three toes. They are not real claws, but cornified tips. Even so, they are sharp and the frog uses them to shred its prey. People have been cut by the claws.
The African Clawed frog is larger than most frogs with females being almost twice the size of males. They range from 5-12 cm (2-4.5 in.). Their heads appear smaller than their bodies and are wedge shaped.
The African Clawed Frog is native to the Rift Valley in Africa and also parts of eastern and western Africa. The species is invasive to many parts of the world. During the 1940s and 1950s the frog was used for human pregnancy testing. An amount of urine from a woman was injected in a female frog and if the woman was pregnant the hormones in the urine would cause the frog to produce eggs. Consequently, the African Clawed frog was shipped all over the world. When technological advances were made and pregnancy tests were conveniently available at the drugstore or doctors office, the frogs were released into the wild.
Since that time, the frog has spread to several countries, including Australia, America, and Europe. They are an unnatural predator for many species and are causing extinctions and disrupting the food chain. Not only did these releases cause ecosystems to be at danger, but the African Clawed Frog is thought to be the carrier of the chytrid fungus. The fungus has caused thousands of frog deaths the world over and has been responsible for the extinction or near extinction of a great deal of frog species.
Like most invasive frog species, the African Clawed Frog is very adaptable. They are hearty and large for a frog. They will eat anything small enough to get in their gaping mouths, including native species of frogs.
They can live in temperatures ranging from 0-30 degrees Celsius. The frogs spend most of their time underwater making it hard to capture them. They can survive in up to 40% salt water and have been found even along sea cliffs. If their entire wet habitat dries up, the African Clawed Frog can aestivate (hibernate) for up to eight months and not eat for a year.
The frogs can reproduce at a very quick rate with females laying up to eight thousand eggs per year as compared to some frogs like the strawberry dart frog that lay on average of five eggs per year. They also have long lives for frogs with an average of 15 years in the wild.
The African Clawed frog isnt all bad though. They secrete an antibody called magainins that can heal wounds rapidly. Perhaps it will someday be adapted for humans to use.
Fun Frog Fact:
A: Yes, the African Clawed Frog uses smell to aid in hunting.