AP BIOLOGY

Detailed explanation-1: -Hair is present in differing degrees on all mammals. On adult whales, elephants, sirenians, and rhinoceroses body hair is limited to scattered bristles. In most other mammals the hair is abundant enough to form a thick coat, while humans are among the most hairless of all mammals.

Detailed explanation-2: -Hair (and a coat of hairs, called fur or pelage) is uniquely mammalian. No other creature possesses true hair, and at least some hair is found on all mammals at some time during their lives. Hairs grow out of pits in the skin called follicles.

Detailed explanation-3: -Mammalian skin forms the outer covering of the body and consists of two major layers (Fig. 1) (5). The upper layer is an epithelium called the epidermis, and the lower layer is a connective tissue called the dermis.

Detailed explanation-4: -All mammals have some hair on their skin, even marine mammals like whales, dolphins, and porpoises that appear to be hairless.

Detailed explanation-5: -Hair is important to mammals for several reasons. They use its form and color patterns for displays and camouflage; they use it for its insulating properties, for self-defense, and even as a sensory organ.