General Characteristics
Grizzly bear (Ursus arctos horribilis) skin is characterized by its thick, shaggy fur. Coloration is highly variable, ranging from blonde to dark brown or nearly black, often influenced by geographic location and individual genetics. The outer fur typically has a coarse texture.
Fur Structure and Composition
The grizzly bear's fur features a two-layered structure essential for insulation and protection:
- Guard Hairs: These are long, coarse outer hairs responsible for the shaggy appearance and the "grizzled" effect due to often lighter tips. They shield the underfur and skin from moisture, dirt, and physical wear.
- Underfur: A dense layer of shorter, finer hairs situated beneath the guard hairs. Its primary role is thermal insulation, trapping air to maintain body temperature in cold conditions.
The underlying skin is thick and durable, hosting the hair follicles and sebaceous glands that produce oils, contributing to the coat's water resistance.
Adaptive Functions
The skin and fur provide critical adaptations:
- Thermoregulation: Excellent insulation from cold via the dense underfur, with seasonal shedding to manage heat.
- Physical Protection: The robust hide and coarse guard hairs defend against environmental hazards and minor injuries.
- Water Resistance: Oily secretions and guard hair structure repel water, keeping the underfur dry and effective.
- Camouflage: Variable coloration can provide a degree of camouflage in diverse environments.
Coloration and "Grizzled" Appearance
The "grizzly" designation originates from the silver or yellowish-brown tips of the guard hairs, most noticeable on the bear's back and shoulders. This creates a frosted or "grizzled" look over the base fur color, which itself varies widely. The extent of grizzling can change with age and season.
Molting
Grizzly bears undergo an annual molt, shedding their heavy winter coat in late spring or early summer. This results in a temporarily patchy or unkempt appearance. A new, dense coat develops by late summer or autumn, preparing the bear for winter.
