The white rhinoceros or square-lipped rhinoceros (Ceratotherium simum) is the largest extant species of rhinoceros. It has a wide mouth used for grazing and is the most social of all rhino species. The white rhinoceros is considered to consist of two subspecies: the southern white rhinoceros, with an estimated 20,000 wild-living animals as of 2015, and the much rarer northern white rhinoceros. The northern subspecies has very few remaining, with only three confirmed individuals left (two females Fatu, 15 and Najin, 25 and one male Sudan, 42), all in captivity.