Whiskers

Whiskers, also known as vibrissae, are special sensory hairs that help most mammals feel their way through the world. These tiny hairs act like super-sensitive feelers, helping animals notice air movements and objects around them. This helps mammals move, find food, and know where they are without using their eyes.

Whiskers grow in groups on different parts of an animal’s body, like above the eyes, on the chin, and near the ears. Almost all mammals have whiskers, especially those that are active at night. However, a special group of mammals called monotremes do not have whiskers at all.

Even though only mammals grow true whiskers, many other animals, such as birds, fish, insects, and crustaceans, have similar structures that help them sense their surroundings in much the same way.

Etymology

The word "vibrissae" comes from a Latin word meaning "to vibrate." It describes the way these special hairs move when a small rodent is sitting still. In humans, these thick hairs are found inside our nostrils.

thick hairs nostrils

Evolution

The last common ancestor of all mammals today had special hairs called whiskers. Scientists think this ability might have started even before true mammals existed, in ancient animal groups during a time called the Triassic period. Most mammals today, except for great apes, still have these whiskers and the special face muscles that help move them.

Anatomy

Whiskers are special hairs that help mammals feel their way around the world. Unlike regular fur, whiskers are stiffer, thicker, and longer. They grow from special follicles that have many nerves, helping the animal sense things around it.

Many mammals have whiskers in groups on their faces. Land animals like rats and hamsters often have four main groups: above the eyes, on the cheeks, where a mustache would be, and under the snout. These whiskers help the animals navigate, find food, and know where their paws are when they move. Marine animals like whales and dolphins have different whisker arrangements, sometimes around their blowholes instead of their snouts. Whiskers can be very long, sometimes more than a third of the animal's body length, and they help these animals sense their environment in ways that eyes cannot.

Main article: follicles

Main articles: somatosensory cortex, Marine mammals, whales and dolphins, Florida manatee, electroreception, keratin, nerves, blood, sinus, guinea pig, afferent nerve cells, mechanoreceptors, sensory nerve, Euler spiral, chinchilla

Operation

The follicles of whiskers on some animals can move. Tiny muscles at the base of each whisker let mammals change the position of their whiskers.

Whiskers help animals feel their way, especially when they can’t see well, like at night or in muddy water. They can also sense wind and show an animal’s feelings, such as fear or curiosity. Whiskers are important for many animals, including rats, in social behavior and finding food.

Marine animals like seals use their whiskers to feel vibrations in the water, helping them find food even in the dark. These whiskers are very sensitive and can detect fish swimming by. Some seals can follow trails left by fish minutes earlier. Unlike land animals, seals keep their whiskers still to get the best sense of their surroundings. Research continues to learn more about how these whiskers work.

Lines of research

Neuroscience

In many mammals that use whiskers, a big part of their brain works to process signals from these special hairs. These signals travel through the trigeminal nerve to the brain. They first reach a part of the brain called the trigeminal sensory complex in the brainstem. From there, the signals go to places like the thalamus and a special area known as the barrel cortex. Scientists study this system a lot because it is simpler to understand than vision, and lab rats and mice rely more on whiskers than sight.

Evolutionary biology

Whiskers appear in many different groups of mammals, like Rodentia, Afrotheria, and marsupials, and they work in similar ways. This suggests that whiskers might have been a feature in a shared ancestor of all therian mammals. Even some humans have small muscles in their upper lip that are reminders of this ancient trait, showing that whiskers may have been important in the evolution of mammals.

Artificial whiskers

Scientists and engineers have created artificial whiskers to learn more about how real whiskers work and to give robots a sense of touch. These artificial whiskers vary widely, from simple models to robots designed to mimic animals with whiskers, such as ScratchBot and ShrewBot made by the Bristol Robotics Laboratory.

In non-mammals

Some animals that are not mammals have special features that work like whiskers to help them feel their way.

In birds

Certain birds have special feathers near their beaks that act like whiskers. The whiskered auklet has stiff white feathers above and below its eyes. When these feathers were covered, the auklet bumped into things more often, showing these feathers help it sense its surroundings. Other birds with similar feathers include kiwis, flycatchers, swallows, nightjars, whip-poor-wills, the kākāpō, and the long-whiskered owlet.

In fish

Some fish have long, thin feelers near their mouths, often called "whiskers." These are correctly known as barbels. Fish with barbels include the catfish, carp, goatfish, hagfish, sturgeon, zebrafish, and some kinds of shark. The Pimelodidae family of catfishes is known for its long barbels.

In pterosaurs

Anurognathid pterosaurs may have had special textures on their jaws where whiskers could have attached, though no actual whiskers have been found. Recently, special feathers were discovered around the mouths of these pterosaurs.