blubber	~layer of fat beneath an animal's skin (such as the polar bear) with the purpose of helping the animal keep its heat in
	carnivore	~animal that feeds on animals
	den	~a cave where a bear goes for shelter and to give birth to its young
	guard hairs	~the long coarse outer hairs (hollow and transparent on a polar bear); the fur with the purpose of keeping a polar bear's body heat next to its skin and shedding water
	habitat	~the surroundings in which an animal lives
	herbivore	~an animal that eats only plant matter
	hibernation	~a time of long sleep that some animals undergo during the harsh time of year
	mammal	~warm-blooded  animal with a backbone and fur or hair, and that feeds its young with the mother's milk
	omnivore	~animal that feeds on both plants and animals
	plantigrade	~describes and animal that walks with the entire lower part of its foot  on the ground, such as a human and a bear
	species	~a group of animals (or plants) that have the same characteristics that make them like each other but different from other types
	torpor	~the state of lethargy (slowed being) into which some animals fall during the colder months  of the year
	underfur	~the short hairs close to a polar bear's skin; the fur with the purpose of keeping a polar bear's body heat next to its skin