A common question arises when observing their thick outer covering: do bears have fur or hair? This query often leads to confusion, as the terms “fur” and “hair” are frequently used interchangeably. While both refer to the filamentous growths covering a mammal’s body, scientific distinctions clarify a bear’s unique coat.
The Nature of a Bear’s Coat
Biologically, “fur” is a dense growth of “hair” that covers most mammals. Both are composed of keratin. From a scientific standpoint, all fur is hair, but not all hair is referred to as fur. Mammals like bears possess a specialized coat often described as fur due to its layered structure and density.
A bear’s coat typically consists of two distinct layers: an outer layer of guard hairs and a dense undercoat. The guard hairs are long, coarse, and stiff, forming the visible outer layer of the coat. Beneath this outer layer lies the undercoat, which is composed of softer, shorter, and finer hairs. This undercoat is also known as down hair or underfur.
Functions of Bear Hair
The hair that makes up a bear’s coat serves multiple functions for its survival. One primary purpose is insulation, important for bears living in cold climates. The dense undercoat traps a layer of air close to the bear’s skin, creating an effective barrier that minimizes heat loss. This trapped air acts as a poor conductor of heat, maintaining the bear’s body temperature even in frigid conditions.
The outer guard hairs also provide protection. They shield the softer undercoat from dirt, abrasion, and moisture. These coarse hairs also offer defense against minor injuries and insect bites. The color and pattern of a bear’s coat also contribute to camouflage, helping the animal blend into its surroundings. For instance, the transparent, hollow guard hairs of polar bears scatter light, giving them a white appearance that allows them to blend with snow and ice.
Another important function of bear hair is water repellency. The guard hairs are naturally structured to shed water, often possessing an oily or hydrophobic surface. This property prevents the undercoat from becoming waterlogged, which would compromise its insulating capabilities. For polar bears, the hair secretes specialized lipids, including cholesterol and diacylglycerols, which actively prevent ice from adhering to their fur, allowing them to remain ice-free even in extremely cold, wet environments. This allows them to maintain insulation even after swimming.