Of the five species of rhinos, white and black rhinoceros are native to Africa and the other three Sumatran, Indian, and Javan are found in Asia. Although the black and white rhinos have the same skin color, yellowish brown to slate grey, they are easily distinguished. The black rhino is much smaller and has a pointed mouth which can be used for picking leaves whereas the white rhino has a flat broad mouth for grazing. The African rhinos lack teeth in the front of their mouth so they must grind plants with their powerful molars.

In the wild adult rhinoceros have few natural predators except humans who kill them for their horns, which are illegally traded on the black market for ornamental or medicinal purposes. Rhino horns are pure keratin just like human hair and fingernails. White, black, and Sumatran rhinos have 2 horns while Indian and Javan rhinos have only one horn.

Critically endangered rhinoceros species include the Javan, Sumatran and Black. On November 10, 2011 the Western Black Rhino was declared officially extinct by the IUCN.

Organizations that help:
http://www.rhinos-irf.org/