For humans, touch is a sense most often associated with the fingers. But man's best friend, the dog, touches the world a different way — with his face.

Whiskers, or vibrissae, are long, coarse hairs protruding from a dog's muzzle, jaw and above its eyes. The follicles at the base of these hairs are packed with nerves that send sensory messages to a dog's brain.

Highly sensitive to subtle changes in air currents, canine whiskers serve as receptors for important information about the size, shape and speed of nearby objects. This helps dogs — for whom vision is not the most highly evolved trait — "see" objects more clearly, even in the dark. Being able to feel vibrations in the air also helps dogs sense approaching dangers.

Some dog breeds have also been known to use their whiskers in the same way that many smaller mammals do: to determine whether they can fit through small spaces. And while few studies have been conducted to determine whether dogs also use their whiskers to locate food, it is likely that at one time in canine history, this was the case, as rats, seals, walruses and many other nocturnal or aquatic mammals still use vibrissae for this purpose.

Apart from the tactical advantages of whiskers, these special facial hairs can also relay messages about how a dog is feeling. When a dog is threatened, it will often reflexively flare its whiskers and then point them in a forward direction. Some scientists believe this behavior indicates that whiskers play some part in a canine's defense strategy during combative situations with predators and other dogs.

Despite the apparent advantages of having whiskers, many pet owners — particularly those who "show" their dogs — opt to pluck, trim or surgically remove these vital sensory tools. Anecdotal evidence suggests that tampering with a dog's whiskers can lead to confusion and decreased spatial awareness.

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