Final answer:
The hair that grows around the neck of some quadrupeds, known as a mane, is made of keratin-filled cells and serves important functions such as protection and communication within mammal species.
Step-by-step explanation:
Hair in Mammals
The hair that grows around the neck of some quadrupeds, often referred to as a mane, is a common characteristic among certain mammal species. Hair serves several homeostatic functions in mammals, including thermoregulation, protection from UV radiation, and enhancing sensory input. It is composed primarily of keratin and originates from follicles in the dermis layer of the skin. As the hair grows, the living cells in the bulb area are pushed upward, becoming the dead, keratin-filled cells that make up the visible hair shaft.
Mammals have unique features such as hair or fur, sweat glands, and mammary glands, among other specialized structures. These features are important for survival and adaptation in various environments. In particular, the mane or neck hair can offer protection, aid in communication, and even be a sign of vitality or attractiveness within a species. This distinguishes mammals from other animals, which do not have hair.
For example, lions are known for their distinctive manes which play a role in protecting their neck during fights and as a display to attract mates. The development of hair in mammals is a complex process involving keratinocytes, and it provides a first-line defense against external factors, as well as aiding in various sensory functions.