Notes from Papaw: Sharks!

Do you like sharks? Many people say they like sharks, but only if they can see them in an aquarium. That way they don’t get bitten. Some sharks are dangerous. I don’t think I would want to meet a great white shark while I was swimming in the ocean. But many sharks are just fine hunting for small fish or crabs along the bottom. Some sharks have huge teeth. Others have teeth so small it feels like sand paper. There are many different kinds of sharks. There are more than 500 different species. The smallest, the dwarf lantern shark, is only about 7 inches in length. The largest, the whale shark, can be 40 feet long. It has a huge mouth but eats only tiny animals called plankton. The hammerhead shark has a flat shovel-shaped head. They look really cool! Most sharks live in salt water, but some can visit freshwater rivers for a time. One shark, the Ganges shark live in fresh water all the time.

Sharks don’t have a skeleton. They have a skeleton made of cartilage. It’s the same kind of stuff you have in your ear. It makes them very flexible. The only bones they have are their jaws and teeth. That’s why it’s hard to find fossil sharks.

A sharks skin is amazing. If you rub its skin from front to back (be sure to avoid the teeth) it feels fairly smooth. If you rub its skin in the other direction, from tail to head, it feels very rough. In the old days, carpenters used to use it as sandpaper! This kind of skin helps them glide through the water.

Most sharks are cold blooded, which means they are the same temperature as the water around them. Great white sharks can raise their body temperature by moving their muscles. This lets them survive in colder waters and stay active.

Sharks are very helpful for the ecosystem. In coral reefs they are important in keeping fish populations under control. Otherwise all those fish might eat the whole reef and kill the coral.