Their solid horns are made of compressed, fibrous keratin, like our fingernails only much, much stronger. They also have small eyes and short but prominent erect ears. Rhinos have very thick skin and are sometimes called pachyderms, like elephants or hippos. Their thick skin is folded or creased, producing the appearance of riveted armored plates in some species. Basically the only hair on a rhino is on its stiff bristled tail.
Rhinoceroses are basically solitary and territorial except for mothers with young.
Groups of adult cows or bachelor bulls are sometimes formed, and during the mating season pairs of rhinos may stay together for up to 4 months. Female rhinos give birth about every 2 years to a single calf. The calf is active soon after birth and remains with the mother until the next offspring is born. The potential life span is approximately 50 years. African and Asian Rhino are similar in many ways but also have differences.