Ursidae- the bear family

The Ursidae, or bear family, is made up of seven genera and about nine species, most of them residing in the Northern hemisphere and and northern South America. For the most part bears are not indigenous to the regions of Africa, Madagascar, Australia, most oceanic islands or the Antarctic. Genus Tremarctos has only one species and is the only bear that resides in South America. This bear is commonly known as the spectacled bear due to the white markings around its eyes. The genus Selenarctos also contains only one bear, the Asiatic black bear. Residing in Asia, this bear lives high in the mountains, far from civilization.

Genus Ursus is, by far, the widest spread and most highly populated genus. It includes the Grizzly bear and the brown bear, both of which can be found across the entire continent of North America, as well as, sparsely across parts of Europe, Asia, and parts of North Africa. Another genus with only one species in Euarcturos, the American black bear. This bear is exclusive to the North American continent and has long been a feature of Indian folklore as a symbol of wisdom and strength. The polar bear also belongs exclusively to its own genus, Thalarctos and is found in the arctic regions of the North Pole. The sloth bear, melursus ursinus, lives in the forested areas of India and Ceylon, have shaggy hair and a y-shaped mark on their chests. The Malayan sun bear is in the last genus Helarctos, and can be found in the forests of the southern Asian continent. It is the smallest bear of all the genus, weighing in at only 55-150lbs and measuring about three and a half to four and a half feet in length.

Bears evolved fairly recently by geological standards. It is believed that they share a common ancestor with the dog and wolf. Around 18 million years ago their ancestors started to change, their skulls becoming heavy and huge, their teeth blunt and short, their legs stocky and tails fading to stubs. It is believed that they evolved this way due to the environment and the way they lived. They no longer chased after their prey, they began to eat tough plant material as well as meat. It appears they sacrificed speed for strength.

Modern bears still retain many of these characteristics. They have large heavy bodies with extremely powerful limbs. Each limb has five strong, sharp claws which are used for tearing and digging. Bears have an unusual gait due to the fact that they walk flat footed like man, instead of on their toes as the Canidae do. Also like man, they can rotate their forearms, giving them great agility and strength when grabbing prey. Most bears are still partly carnivorous, excluding the sloth bear (mentioned earlier) which is a vegetarian. Despite their large, lumbering size, bears can move extremely fast, some running up to 30 miles an hour! Most of the lighter species are also good climbers. Bears who live in the temperate and cold regions, gain quite a bit of weight when winter approaches. Once cold weather arrives, the bears seek shelter and go into a deep sleep resembling hibernation. Despite the freezing temperatures, the polar bear does not hibernate during the winter, except for pregnant females.