The first rhinoceroses began lumbering around the earth about 50 million years ago. But some of these giant horned beasts -- like the woolly rhino, covered in a thick mat of curls -- looked a bit different than the rhinos that live today.
4. Rhinos communicate with squeaks, snorts and grunts (and poop).[Image credit: Park Street Pro]
Black rhinoceroses use a variety of sounds to convey emotion: snorts for anger, huffs for greetings and even confused squeaks. They also leave behind piles of pungent droppings to mark territory.
5. Rhinos make their own sun block.[Video credit: YouTube]
Rhinos -- which will soak in muck for up to three hours at a time -- rely on mud to protect their skin from biting pests and the blistering sun.
6. Rhinos come in five types.[Image credit: rosshuggett]
There are five species of rhinoceros: black, Indian, Javan, Sumatran and white. Somewhat confusingly, white rhinos aren't white and black rhinos aren't black -- all rhinos have grayish skin.
7. Those horns look impressive? They're really just fingernails.[Image credit: USFWS Headquarters]
Unlike the horns of most animals -- which are mostly bone within a thin envelope of keratin -- a rhino's horn is made of keratin, the same tough proteins that make up human hair and fingernails. That's not to say rhinos are simply sporting curves of stiff hair -- strong mineral deposits run up the core of a rhino's horn like a stick through a popsicle.
Despite persistent myths, ingesting rhinoceros horn powder has the same restorative properties as chewing on split ends -- that is to say, none. But that hasn't stopped poachers from targeting rhinos for their horns, seen as status symbols in places like Vietnam. Which is particularly terrible because:
9. Rhinos are rarer than you think.[Image credit: Lip Kee]
The International Union for Conservation of Nature, which tracks threatened species, lists three out of five types of rhinos as critically endangered: black, Javan and Sumatran rhinoceroses -- with a wild population of fewer than 50, the Javan rhino is the rarest land animal on the planet.