Wednesday, May 14, 2008

The word rhinoceros is derived from the Greek words rhino, meaning “nose,” and keras, meaning “horn,” a reference to the most eye-catching feature of these huge and often awkward-looking animals. Rhino horns are made of a mass of thousands of fibers of keratin, the same substance found in hair. Unlike the true horns found in, for instance, cows and deer, rhinoceros horns do not have a bony core, and they are embedded in skin rather than in the animal’s skeleton. However, as with true horns, rhino horns are permanent and grow steadily throughout their owner’s lifetime.

Some rhinoceros horns are little more than bumps, but in the white rhinoceros particularly, they can reach an impressive size. The largest one on record, from a female white rhino in South Rhinos sometimes use horns to get at food, but a horn’s main function is for defense With so much muscle-power behind them, horns make formidable weapons. Unfortunately, horns are also the main reason for the rhino family’s endangered plight. On the black market, rhinoceros horns command astronomical prices for use as dagger and sword handles in the Middle East and as an ingredient for traditional Chinese medicine.

Rhinoceros skin is remarkable, both for its thickness and its texture. African rhinos have fairly smooth skin, but in the Asian species skin hangs down in heavy folds. The skin of the Indian rhinoceros forms platelike folds that give the appearance of armor plating. It is covered with tubercles, hard lumps that look like rivets holding the animal’s armor together. Four out of the five rhino species are almost hairless, but the Sumatran rhino is born with a thick coat of hair, which becomes more straggly and bristly as it ages.

Rhinos have elongated heads, with small, puffy-looking eyes. Because their eyes face sideways, they have to turn their heads one way and then the other to look at anything in front. This impediment coupled with their weak eyesight means that rhinos often fail to spot danger—a motionless person thirty mtr ahead is more or less invisible to a rhinoceros. However, rhinos quickly scent anything that is upwind, and their ears flick in different directions to pick up the faintest sounds.

Rhinos have few or no front teeth, but their cheek teeth, or molars, are well developed for grinding up food. A rhino’s lips also play an important part in feeding, and their shape helps to show what it eats. In most species the upper lip is pointed and prehensile (able to grasp), and is used for collecting twigs and leaves. But in the white rhino, the upper lip is wide, enabling this species to pull up mouthfuls of low-growing grass.

Male and female rhinos have a similar physical appearance, although male rhinos are usually larger than females, with the size difference varying between species. In the wild, some rhinos probably live into their late forty's, and they have survived into their thirty's in captivity.