The rhinoceros’ lineage is an ancient one, and through time there have been close to 100 known rhinoceros species. Today, there are only five species: two in Africa and three in Asia. Rhinos have one or two horns, a broad chest, thick skin, excellent hearing, and a fondness for rolling in dust or mud as protection against sunburn and insect bites. Because rhinos are nearsighted, they may charge when startled, and rhinos have been observed charging at boulders or trees. That’s given them an undeserved reputation for having a bad temper. A rhino’s horn is made of keratin, the same material as our fingernails and hair. Unfortunately, the horn is also what poachers are after, leading to the endangerment of all rhino species.