The common Platanna - Xenopus laevis

In the nineteenth century European scientists discovered an unusual amphibian in Cape Colony (South Africa). They called it "Le Crapaud Lisse" (smooth skinned toad), and named it Xenopus (strange foot) laevis (smooth). Xenopus laevis - drawing by Tim ColbornThe animal was already well known by native peoples throughout sub-Saharan Africa as a source of protein and an aphrodisiac or fertility medicine (Kobel et al., 1996). Ease of maintenance and breeding with injected hormone, has made X. laevis the standard laboratory amphibian since the 1940's (Gurdon, 1996).  Being aquatic throughout their life Xenopus are easy to keep and are resistant against disease and infection. Although crude, the use of X. laevis as an assay for luteinising hormone, and thus pregnancy testing, led to mass movement of the humble Platanna to laboratories pan-globally. Subsequent use of X. laevis as the laboratory amphibian in schools, universities, pregnancy clinics, medical research establishments, and as pets, has meant that this animal is familiar to biologists the world over, and has even established feral populations.
 
Little has been added on the subject of feeding and diet in Xenopus since the observations made by Leslie (1890), who wrote; "Unlike other frogs, it feeds in the water, on insects, small fishes, or even young and larvae of its own kind, and is apparently unable to feed out of that element. The mode of eating is by forcing the prey into the mouth by means of the hands, which act as a pair of claspers; the deglutition always takes place under water." X. laevis capturing prey out of water - from Measey (1998)A recent review of diet in Xenopus reinforced these observations of reliance on aquatic invertebrates and cannibalism, based on the gut contents of several species in native and feral habitats (Tinsley et al., 1996). However, recent studies of behavioural feeding mechanisms have shown this aquatic frog to be proficient at catching prey out of water with very fast striking movements (around 10 m s-1) which minimise the risk of attack by predators and maximise the chances of capturing prey with rapid escape reflexes. This movement is faster than any other previously recorded for Xenopus (Measey, 1998). The mechanism explains the presence of some of the terrestrial components in the diet of Xenopus, although it seems likely that there are other mechanisms through which terrestrial prey may be acquired.
 
More has been published on Xenopus laevis than any other amphibian, and yet its ecology is still relatively unkown. This is partly due to unusual aquatic nature of this frog, making techniques for studying it unlike those of other amphibians; but also that it's feeding and burrowing behaviours render the water it occupies extemely turbid. A number of techniques have been used to enable the study of extralimital and natural populations.

Take a look at these papers

John Measey, 1998      
Department of Zoology
University of the Western Cape
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Bellville 7535
Cape Town
South Africa

Tel: 021 - 959 2261
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jmeasey@uwc.ac.za