There are about 17,000 southern white rhinoceros grazing in the South African wild. The average male is about 5,000 pounds. The largest is nearly twice as heavy. This rhino’s two horns poking out from between the rocks at the Philadelphia Zoo are made from a protein called keratin. This is the same material found in human fingernails. The front horn extends from three to five feet. The rhino is hairless, except around its tail and ears.