Final answer:
Mammalian hair, which contains keratin, has multiple functions including insulation, sensory input, and communication. The fat layer under the skin serves as insulation, energy storage, and aids in temperature regulation by attaching the skin to underlying bone and muscle.
Step-by-step explanation:
The function of hair in mammals is multifaceted. Hair, which is made up of keratin, provides insulation by trapping a layer of air close to the body, preserving heat. This is particularly important as mammals are endothermic, meaning they generate their own body heat. Hair also plays a sensory role, particularly through specialized hairs called vibrissae or whiskers, which connect to nerves that help mammals sense their environment. Moreover, hair aids in protecting the skin from ultraviolet (UV) radiation and can be involved in communication, such as when animals raise their fur to appear larger to predators.
The fat layer under the skin, also known as the hypodermis, holds a significant portion of the body's fat and is crucial for insulation, protecting internal organs, and energy storage. It attaches the skin to underlying bone and muscle while providing nutrients and nerve supply to the skin. The hypodermis also contributes to the regulation of body temperature.