Known in the rest of the world as the African Clawed Frog, there are three kinds of Platannas found in South Africa:
- Xenopus gilli, the Cape Platanna, which occurs only in a narrow strip along the coast from Cape Town to Cape Agulhas. It is considered to be critically endangered due to habitat loss and fragmentation of their population. Grows to about 6cm long.
- Xenopus muelleri, the Tropical Platanna, which occurs in extreme northern Kwazulu-Natal and the Lowveld of Mpumalanga and Limpopo, extending further as far as southern Kenya. Measures around 9cm in length.
- Xenopus laevis, the Common Platanna, found over most of South Africa and our neighbouring states. Can grow to almost 15cm in length.
Platannas are almost entirely aquatic amphibians that will only leave the water to migrate to new water bodies, which usually happens during rainy periods or when their current abode dries out (and in the latter instance they might just as easily dig themselves into the mud to aestivate until the water returns). They’re commonly found in almost every fresh water habitat, whether natural or man-made. Platannas are carnivores that feed on a wide variety of aquatic creatures ranging in size from zooplankton to fishes and even their own young. Unlike other frogs they don’t have long, sticky tongues but will use their hands and fingers to hold onto food and push it into their mouths.
Platannas breed at the start of the rainy season, when the male holds onto the back of the female – a position known as amplexus – and the couple then swims around their pond to deposit several hundred eggs singly on solid objects. The tadpoles hatch within two days and metamorphose quickly, being capable of fully transforming into adult form within 2 to 4 months of hatching depending on temperatures and food supply. Platannas are a favourite food item for many kinds of large fish, reptiles, birds and mammals but may live to 15 years old in the wild.
Between the 1930s and 1960s Platannas were used in crude but reliable pregnancy tests, as the females will start laying eggs within hours of being injected under the skin with the urine of a pregnant woman. They’re still widely used in experiments and biological studies, and this is likely the method by which they’ve become exotic invaders in many places of the world beyond their natural distribution in Sub-Saharan Africa.