Vibrissa

Whiskers or vibrissae (/vaɪˈbrɪsi/; singular: vibrissa; /vaɪˈbrɪsə/) are a type of mammalian hair that are typically characterised, anatomically, by their large length, large and well-innervated hair follicle, and by having an identifiable representation in the somatosensory cortex of the brain.

They are specialised for tactile sensing (other types of hair operate as more crude tactile sensors). Vibrissae grow in various places on most mammals, including all primates except humans.

In medicine, the term vibrissae also refers to the thick hairs found inside human nostrils.

Vibrissae (derived from the Latin "vibrio" meaning to vibrate) typically grow in groups in different locations on an animal. These groups are relatively well conserved across land mammals, and somewhat less well conserved between land and marine mammals (though commonalities are certainly present). Species-specific differences are also found. Vibrissae of different groups may vary in their anatomical parameters and in their operation, and it is generally assumed that they serve different purposes in accordance with their different locations on the body.

Many land mammals, for example rats and hamsters, have an arrangement of cranial (of the skull) vibrissae that includes the supraorbital (above the eyes), genal (of the cheeks), and mystacial (where a moustache would be) vibrissae, as well as mandibular (of the jaw) vibrissae under the snout. These groups, all of which are visible in the accompanying image of the Patagonian fox, are well conserved across land mammals though anatomical and functional details vary with the animal's lifestyle.

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