The sitatunga (Tragelaphus spekii) or marshbuck is a swamp-dwelling medium-sized antelope found throughout central Africa. The body and legs of this antelope are specially adapted to its swampy habitat. The hooves of the male are elongated and widely splayed. The rubbery, shaggy, water-repellent coat is minimally affected by slimy and muddy vegetation. The wedge-like shape and lowering of the head, coupled with the backward bend of the horns (in males) provides for easy navigation through dense vegetation. Sitatunga are good swimmers, but limit themselves to water with profuse vegetation in order to escape crocodiles. In some cases, for instance when troubled by flies or pursued by predators, the sitatunga might fully submerge themselves in the water except for the nose and the eyes, which they keep slightly above the water surface. Due to its close association with water, the sitatunga are often described as "aquatic antelopes". Habitat loss is the most severe threat to the survival of the sitatunga. Other threats include the increasing loss of wetlands, that has isolated populations; and long-term changes in the water level, that affects the nearby vegetation and thus bears upon their diet. The inaccessibility of its habitat has rendered population estimates very difficult. In 1999, Rod East of the IUCN SSC Antelope Specialist Group estimated a total population of 170,000, but this is likely to be an overestimate.