Rat-natomy: Whiskers

Those Wonderful Whiskers

    To the naked eye, the rat’s whiskers may look like just hairs, but to the rat, they are much, much more. Rats don’t see very well with their eyes, but their whiskers more than make up for this. In fact, rats rely more heavily on their whiskers than they do on sight.

   Rat have long whiskers that grow in rows on either sides of the noses, from their eyebrows, cheeks and mouth.  Each whisker grows from a follicle that is sealed by a capsule of blood (called a blood sinus); when a whisker is touched or bent, it moves inside the sinus and triggers nerves that send a message back to the rat’s brain.  The rat can tell which direction and how far each whisker is moved.  Each whisker is extremely sensitive, more sensitive than a human’s fingertips. Scientists have been able to train rats to distinguish between different grits of sandpaper!

   There are also muscles attached to each whisker follicle, and rats sweep their whiskers back and forth constantly to learn about their surroundings.  If they want to, rats can even move their whiskers independently, moving whiskers on the same side of the face in opposite directions during a whisk. They can also extend their whiskers as far as two inches in front of their noses.  These whisker sweeps hit objects around the rat as it moves, actually giving it a 3-D picture of their surroundings.

   New studies have also discovered that whiskers may actually help the rat to hear too; each whisker resonates with a different frequency, much like the strings of a harp.  Low sound frequencies and course textures both cause longer whiskers to vibrate.  High frequencies and fine textures vibrate the short whiskers.  The different sized whiskers help the rat distinguish textures and may also give them the ability to ‘hear’ through the air.  Not much is known about this ability yet, but scientist are studying the rat brain to see just how much a rat can learn from it’s amazing whiskers!

  At short distances, rats rely more on this whisker technology than eyesight; using it to perceive distances, navigate, orient themselves, find and discriminate food, and measure the size of openings.  Rats flourish their whiskers like a shield in a fight, using them to block an attack. Whiskers can feel the wind, measure distances to water (both in and out of it); rats without whiskers will actually drown in water because they can’t tell where the surface is!  A rats without whiskers may be more impaired than a rat who is blind!