Keep in Touch Here’s something your epidermis doesn’t do. If you cut or scrape it, your epidermis won’t hurt. It won’t bleed, either. It can’t. It takes nerves to feel pain. It takes blood
vessels to bleed. You don’t have any nerves or blood vessels in your epidermis. Don’t breathe a sigh of relief yet. T e next layer of skin tissue is packed with them. T is layer of skin is called the dermis. You
can’t see it. T anks to your nerves, though, you know it’s there. About 72 km of nerves run through this part of your skin. T is network of nerves has millions of endings. Nerve endings sense changes in the environment. If something pokes you, your nerves sense
the pressure. If a band starts jamming, nerves sense the vibrations from the loud music. Pick up an ice cube, and they sense the temperature. T e nerves send signals to your brain. T en
you can feel the sensations. All of this happens faster than you can blink.
These striped catfi sh have very sensitive skin.
This catfi sh’s
sensitive skin helps it fi nd food and avoid
Super Sensitive With all of these nerves, you’d think humans would have the best sense of touch of any creature. T e truth is we’re not even close. Many animals have a better sense of touch
than we do. A catfish is a good example. Unlike many fish, it doesn’t have scales on the outside of its body. It just has skin. T e nerves in its smooth skin help this
fish find food. It hunts at night in muddy waters. It’s dark and murky. T at’s not a problem for this fish. Parts that look like whiskers stick out around its mouth. T ey’re covered in sensitive skin. T ey feel about in the water and muck. As soon as they feel a fish or other prey, zap! T e catfish gulps its meal. T e nerves in its skin also protect it from
danger. Special hair-like nerves run in a line down the sides of its body. T ey sense movement. When a fishing line drops in the water, the water ripples. T e catfish feels the motion and swims away.
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