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There are six species in the genus Ursus: American Black Bear, Asiatic Black Bear, Brown Bear, Polar Bear, Sloth Bear, and Sun Bear. Species can be distinguished by size, build, coloration, and habitat. I am mainly focusing on the Polar Bear though because it is my favorite!
The Polar Bear's Scientific Classification is Ursus Maritimus, which is Latin for "Sea Bear."
DESCRIPTION
Polar Bears are the largest carnivore and bear species, weighing in at between 440 and 1760 pounds with an overall length of 8' 5". They have a distinctive all white coat, long neck, and small ears. A Polar Bear's nose, lips and all skin under thier fur is black. (Which absorbs heat) Their front paws are very wide fore paddling through Arctic waters, and they use their back paws for rudders. The soles of their feet are covered with vacoules that actually act as suction cups while walking on ice. Their heavy , dense underfur, and thick layer of insulating fat allows them to maintain a normal body temperature when the outside temperature drops to -37C.
FOSSIL RECORD
The oldest known Polar Bear fossil is less than 100,000 years old. Polar Bears probably developed during the Pleistocene era from an ancestral Brown Bear. Polar Bears and Brown Bears are still closely related.
HABITAT
Polar Bears inhabit Arctic sea ice, water, islands, and continental coastlines. They prefer sea ice habitat with elads, next to continental coastlines or islands. Leads are water channels or cracks through ice which may remain open for only a few minutes to several months, depending upon weather and water conditions. Polar Bears hunt in the leads, using ice as platforms.
Air temperatures in the Arctic average -34C (-29F) in winter and 0C (32F) in summer. The coldest area in winter is Northeastern Siberia, where temperauters have been recorded as low as -69C (-92F). The warmest areas in summer are inland regions of Siberia, Alaska, and Canada where temperatures can reach as high as 32C (90F).
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SENSES
A Polar Bear's HEARING is probably as sensative as human hearing.
The EYESIGHT of Polar Bears appears to be similar to human's. Polar Bear's have a protective membrane over their eyes to help protect them from ultraviolet lights.
Little is known about a Polar Bear's sense of TOUCH. However, Polar Bears have been observed delicately moving or touching objects with the nose, tongue, and claws.
Polar Bears prefer certain foods, but researchers don't know how acute the sense of TASTE is or how important it is in food preferences.
A Polar Bears sense of SMELL is very acute, and it is the most important sense for detecting prey on land. a Polar Bear can smell a seal more than 32 km (20 mi) away.
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BIRTH AND GROWTH OF YOUNG
Females need to gain at least 200 kg (441 lbs) for a successful pregnancy. Most adult females give birth once every three years. In some populations, birth occurs once every two years. The most frequent litter size is two, followed by litters of one. Litters of three are less common than twins or singels, and litters of four are rare. At birth, cubs weigh about 16-24 oz. and are about 12 in. long. By the time the mother and cubs emerge from the den at two months, the cubs weigh 22-33 lbs. When the cubs are 30 months old, they may weigh 99 lbs. (Yikes!) The mother is very protective of her young, even risking her own life in her cub's defense. When the cubs are 30 months old, either the mother or her new mate will chase the cubs away.
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