All About Sharks-seven paragraphs

Essay by packchris88Junior High, 8th gradeA+, April 2004

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Did you know that there are more than 350 species of shark? Some of the most common types of sharks are the angel sharks, saw sharks, and cow sharks. Sharks have a strange fossil record consisting of mainly teeth. The shark is also considered to be the perfect predator. Sharks come in all different shapes and sizes. Sharks are also known to sometimes attack people.

Some of the main types of sharks are the angel sharks, saw sharks, and cow sharks. Squainiformes, or also known as the angel sharks, are characterized by their ray like flattened bodies. This order has one family that is called Squatindae that contains about 13 species. The maximum size that can be reached by any one of these species is 4-6 feet in length. Pristiophoriformes are also known as the saw sharks. This order has only has one family, Phistophoriformes, which contains five species.

These sharks are easy to recognize because they have an elongated blade like snout that is lined with sharp teeth along the edges, which gives them the name saw sharks. Hexanchiformes, or cow sharks, comprise of two families. They are recognized by their six or seven pairs of gill slits. These sharks can often be found in deep water.

Shark fossil records are incomplete at best. Most fossils found so far consist of nothing but teeth; in some cases a few vertebrae have been found. This is rare because sharks do not have bones; instead, they have cartilage which, contrary to common belief, is rather solid. In the rarest of cases complete fossils have been discovered. There were not too many changes in the shark fossils in millions of years. The Hybodonts, who made their appearance some 320 million years ago in the age of the dinosaurs, were...