rhinoceros falls behind only the three extant species of elephant as the largest land animal and terrestrial mammal alive today. It weighs slightly more on average than a hippopotamus despite a considerable mass overlap between these two species. It has a massive body and large head, a short neck and broad chest. The head and body length is in males and in females, with the tail adding another and the shoulder height is in the male and in the female. The male, averaging about is heavier than the female, at an average of about . The largest size the species can attain is not definitively known; specimens of up to are considered reliable, while larger sizes up to have been claimed but are not verified. On its snout it has two horn-like growths, one behind the other. These are made of solid keratin, in which they differ from the horns of bovids (cattle and their relatives), which are keratin with a bony core, and deer antlers, which are solid bone. The front horn is larger and averages in length, reaching as much as but only in females. The white rhinoceros also has a noticeable hump on the back of its neck. Each of the four stumpy feet has three toes. The color of the body ranges from yellowish-brown to slate grey. Its only hair is the ear fringes and tail bristles. White rhinos have a distinctive broad, straight mouth which is used for grazing. Its ears can move independently to pick up sounds, but it depends most of all on its sense of smell. The olfactory passages that are responsible for smell are larger than their entire brain. The white rhinoceros has the widest set of nostrils of any land-based animal. Genome The genome size of the white rhinoceros is 2581.22 Mb. A diploid cell has 2 x 40 autosomals and 2 sex chromosomes (XX or XY). Behavior and ecology White rhinos are found in grassland and savannah habitat. Herbivore grazers that eat grass, preferring the shortest grains, the white rhinoceros is one of the largest pure grazers. It drinks twice a day if water is available, but if conditions are dry it can live four or five days without water. It spends about half of the day eating, one-third resting, and the rest of the day doing various other things. White rhinos, like all species of rhinoceros, love wallowing