Animals that live in the dark underground, or in dark murky waters are often blind. They rely on their sense of touch to find food, find a mate, and to move safely around their habitat.
Different animals have different ways of feeling. Insects have touch sensitive hairs on their antennae and all over their body called sensilla. Mammals touch organs are nerves in the skin. Most mammals have whiskers or vibrissae.
Whiskers allow nocturnal animals to feel their way around when their is not enough light to see by. Whiskers can also keep animals out of too- tight spots. Animals whiskers are generally as long as the animals body is wide. If an animals whiskers do not easily clear an opening, the animal knows it should probably not enter.
If you ever see a cat stalking prey, look closely at its whiskers. When a cat pounces on prey, its whiskers shoot forward. Once the cat has caught it, the whiskers curve downward around the prey to keep track of its movements.