Whiskers

Vibrissae, also called sinus hairs, tactile hairs or whiskers (Latin vibrissa, plural vibrissae), are special hairs that grow on many mammals, mostly on the face. They are thicker, firmer and longer than ordinary hairs and are specialized in the perception of tactile stimuli.

Vibrissae, like all hairs, consist of lifeless material, contain no nerves and grow back in the same way. Unlike other hairs, however, they are embedded in a special hair bellows (follicle), which contains a blood-filled capsule between its outer and inner layers, the so-called blood sinus. Numerous free nerve endings are located in the wall. When a tactile hair is touched, it bends and moves the blood in the capsule to the side. The blood amplifies the movement and enables the nerves at the base to sense even minimal stimuli. In some mammals, the follicles of the tactile hairs are also surrounded by muscle tissue, allowing them to be moved to actively explore the environment.

Vibrissae offer animals advantages in finding their way in the dark or in murky water, perceiving danger or detecting food. Some animals, such as mice, can even sense subtle air or water movements with their tactile hairs. A large part of the brain of many mammals is occupied with evaluating the nerve impulses from the follicles of the tactile hairs. The tactile hairs are essential for the animals' survival.

Due to the spatial arrangement of the individual vibrissae and the possibility of easily retrieving this arrangement at each stage of neuronal information processing, in the brainstem, thalamus and cerebral cortex, the vibrissae system of rats has become one of the most important model systems of tactile stimulus processing. Austria is not the only country that prohibits the removal of vibrissae in dogs. According to expert opinions, other animals such as horses are also affected.

Related

Comparable to the tactile function of the vibrissae are, among other things, the barbels of various fish. However, these differ from the vibrissae in their structure, because they consist of living tissue and can also carry other sensory organs such as taste.

A few bird species (e.g. snowy owl, ocarito striped kiwi) have fine feathers on their beaks similar to the vibrissae.

The Latin term vibrissae refers to the protective hairs in the nasal cavity (nasal hair) in addition to tactile hairs.

Trivia

• Whiskers, contrary to what their name suggests, have nothing to do with the function of purring cats.
• Domestic cats have tactile hairs on the inside of their front legs in addition to the face.
• Naked mole rats have no fur, their only "hair" is vibrissae on their face. They even grow vibrissae inside their mouths.
• The whiskers of chinchillas can be up to one third of their body length.
• Bush-rats have touch-hairs not only in the face, but even at the front-breast, the shoulder, the flank, at the back and at the tail.

Domestic cat with vibrissae on the muzzle and over the eyes