The African helmeted turtle (Pelomedusa subrufa), also known commonly as the marsh terrapin, the crocodile turtle, or in the pet trade as the African side-necked turtle, is a species of omnivorous side-necked terrapin in the family Pelomedusidae. The species naturally occurs in fresh and stagnant water bodies throughout much of Sub-Saharan Africa, and in southern Yemen. This terrapin is typically a rather small turtle, with most individuals being less than 20 cm (7.9 in) in straight carapace length, but one has been recorded with a length of 32.5 cm (12.8 in). It has a black or brown carapace. The top of the tail and limbs are a grayish brown, while the underside is yellowish. The male turtle is distinguished by its long, thick tail. A female tends to have a shorter tail and a broader carapace. A hatchling has a shell size of about 3 cm (1.2 in) in length, and is olive to black in color. It also has two small tubercles under the chin and musk glands in the sides of the carapace. Uniquely, the genus Pelomedusa does not have a hinged plastron (lower shell). All the other species in the family Pelomedusidae, however, do have this feature with which they can, using muscles, close the plastron to the carapace to cover the head and front limbs. Unlike many chelonians, the African helmeted turtle is able, when it finds itself upside down, to right itself with a vigorous flick of its long muscular neck. Recent genetic research suggests that Pelomedusa comprises at least 10 different species, and not only one as previously thought. In the past, the physical differences between populations were not regarded as substantial enough to recognise more than one species. The geographic range of P. subrufa covers a large portion of Africa, from the Cape Peninsula to the Sudan. It can be found as far west as Ghana and as far south as Cape Town. It has also been found in Madagascar and Yemen.