Whisker

A whisker, also called a vibrissa, is a long, stiff hair on the face or body of many mammals that serves an important tactile function. Whiskers differ from ordinary fur in their structure, high innervation, and specialized role in sensing the surrounding environment. They are especially prominent on the muzzle, cheeks, above the eyes, and sometimes on the limbs.

Anatomy and distribution: Each whisker is a hair shaft anchored in a deeply innervated follicle, forming a follicle-sinus complex that makes it extremely sensitive to deflection. Movement can be voluntary, aided by small facial muscles that position the whiskers. Whiskers can be located on multiple regions of the head and body, and their growth cycles are separate from other hairs; they can be shed and later regrow.

Function: The primary function of whiskers is tactile sensing and spatial awareness. Deflection of a whisker signals object location, texture, size, and movement, supporting navigation, foraging, and hunting, particularly in low light or cluttered environments. Histories of whisker use vary among species, with some relying heavily on them to compensate for limited vision. Damage or trimming of whiskers can temporarily impair an animal’s ability to judge distance or surface properties.

In science and technology: Vibrissal systems inspire artificial sensing in robotics, where artificial whiskers or sensor arrays detect airflow and contact forces. The concept of whisker fatigue refers to a temporary decline in sensitivity due to prolonged stimulation. In humans, there are no true vibrissae; facial hair does not function as tactile whiskers.