The Structure Of A Shark

My name is Doctor Shark Body, and I'm your guide to the body of a shark. There are many interesting facts about the physical attributes of a shark and I'll explain them.

General Information About Sharks

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I am going to explain the structure of the shark especially its physical attributes. First, sharks have a boneless skeleton made up of a tough, elastic substance. The name of this substance is "cartilage". Some of the shark species have rounded bodies like a torpedo . Others have flat bodies as thin as a playing card. Others have pectoral fins that help balance the front of their body.

Sharks have a large liver with oil that helps sharks from sinking. Still they must constantly swim to keep from sinking. Sharks have several rows of teeth . New teeth replace old ones regularly, every one to two weeks. Some have molar like grinding teeth, others have razor cutting teeth. Lastly, some have pointed teeth. Most sharks have their mouths on the undersides of their heads. A few have their mouths in front of their heads like the Whale and Angel Sharks.

Small tooth-like scales cover a shark's body. These scales are called placid scales, and they make a shark's skin very rough. Dried shark skin was called shagreen and was used for sandpaper. There are five to seven slits in the skin of each shark on each side of their head. Water passes through these slits after the oxygen is taken. Sharks can't pump water through their gills, so they rely on constant swimming to force water through their mouth and through the gills. This is called ramjet ventilation.