Xenopus laevis it is an important model organism in developmental biology. The species is found throughout most of Africa, and in isolated, introduced populations in North America, South America, and Europe.
Reference: Moss T., Boseley P.G. and Birnstiel M.L. 1980. More ribosomal spacer sequences from Xenopus Laevis Nucleic Acids Research 8(3):467-485