How Do Cat Whiskers Know to Stop Growing?

by Melissa Schindler, Demand Media Google
    Kitty's whiskers help him get around in the dark.

    Kitty's whiskers help him get around in the dark.

    If you ask someone to draw a cat, they'll probably draw a round face, pointy ears and a spray of whiskers. Whiskers are one of Kitty's trademark features, and for good reason. His whiskers help him understand the world around him.

    Whiskers Definition

    Whiskers, or vibrissae, are special hairs around Kitty's nose, cheeks, forehead and the backs of his front legs. He has 24 whiskers around his nose, 12 on either side. They're twice as thick as his normal fur, they're rooted much more deeply, and they serve a special function. He uses them like you use your fingertips. These whiskers are extremely sensitive to touch and can detect not only the sizes of openings, but shifts in air currents and minor vibrations.

    Whisker Width

    The size of Kitty's whiskers is genetically predetermined. This means the length of his whiskers was determined before he was born, and they won't grow longer or shorter depending on his actual adult size. They extend to roughly the same width as his body, or at least to as wide as is healthy for him.
    Once he's full grown they are as long as they ever will be, even if he gains weight. If your cat is very obese, his whiskers won't serve him as well because his body will be wider than they are. A fat kitty can get stuck trying to fit through a small space, because his whiskers can't accurately be used as a measuring stick.
    Because his whiskers are attached to muscles, he can move them forward like feelers, allowing him to judge whether he could fit into a space and to avoid bumping into things.

    Night Vision

    It's a common belief that cats can see in the dark, but this isn't completely true. Although a cat can see in much lower light levels than humans can, he can't see in pitch blackness any more than you can. His whiskers help him get around at night, feeling out the world around him. Shifts in air currents and the slightest vibration keep kitty from bumping into the bed when he comes to cuddle with you at night.
    Whiskers are so important to night vision that species that are nocturnal, such as your feline pal or leopards, have longer whiskers than cats who hunt during the day, such a cheetahs.

    Types of Whiskers

    Touching the little whiskers above his eyes and on his cheeks will trigger Kitty to blink. This helps protect his eyes from something that could injure them. The whiskers on his legs help him when he's climbing, and they aid his paws in feeling out prey. Both of these types of whiskers are finer and thinner than the prominent whiskers beside his nose.
    A cat can move his top two rows of whiskers independently from the bottom two rows, and he'll move them forward when he's investigating something or when he's happy. He can also move them out of the way when he's eating or in a fight, so they don't get damaged.

    Regrowing Whiskers

    Even though Kitty's whiskers will only grow so long, they still fall out and regrow like the rest of his fur, no matter how old he gets. But they will always grow to the same length they were before, even if Kitty has packed on some pounds. Remember, his genes -- not his physical size -- determine the width of his whiskers.
    Whiskers are vital to Kitty's abilities to hunt and to understand his world. Never try to cut or trim Kitty's whiskers. If you do he won't be as successful at hunting, and he'll be a little clumsy until new ones grow in to replace them.

    About the Author

    Melissa Schindler has been writing professionally since 2010. She writes about pets, animals, technology and parenting for various websites. Also a fiction writer, she is author of "Houston After Dark." She has a Bachelor of Arts in English from Texas State University.

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