Xenopus laevis

Xenopus laevis, the African clawed frog (also known as platanna), is a species of South African aquatic frog of the genus Xenopus. It is up to 12 cm long with a flattened head and body but no tongue. Its name derives from its three short claws on each of its hind feet, which it probably uses to stir up mud to hide it from predators.

X. laevis is an important model organism in developmental biology. While it is not blessed with the short generation time and genetic simplicity found in many model organisms it does have a large and easily manipulable embryo. This ease of manipulation in amphibian embryos has given them an important place in both historical and modern developmental biology.

X. laevis is also notable as having been a standard method of pregnancy testing. Human chorionic gonadotrophin is a hormone found in substantial quantities in the urine of pregnant women; when injected into the female X. laevis it induces them to lay eggs.