shark coloring pages
Sharks come in many different shapes and sizes, but most are long and thin (also called streamlined), with powerful jaws. Their teeth are constantly replaced throughout their lives. New teeth grow continuously in a groove just inside the mouth and move forward from inside the mouth on â€œconveyor beltsâ€ formed by the skin in which they are attached to.
Sharks have skin covered in millions of tiny teeth-like scales that point to the tail. If you rub along a shark towards the tail, it would feel smooth, but if you rub the other way, it would be rough. Sharksâ€™ teeth is 20 times as big as human teeth.
Because sharks have skeletons made of cartilage, they donâ€™t fossilize easily. Thatâ€™s because cartilage is softer than bone and falls apart before fossilizing. However, teeth are harder, and if that isnâ€™t enough, they are shed throughout a sharkâ€™s lifetime. Therefore, shark teeth are one of the most common fossils.
Sharks existed for at least two hundred million years before the dinosaurs. The earliest shark fossils were scales, so could it be that the earliest sharks were toothless? We are not sure. Early sharks did not look like sharks of today. For example, the upper snout of modern sharks is longer than the lower jaw. But in early sharks, they were the same length.
The first modern-looking sharks appeared in the Age of Dinosaurs. Sharks back then were preyed upon by giant sea reptiles.
Just a few million years ago, a giant shark called Megalodon swam in the seas. It was 16 meters long, twice as long as the closely-related great white shark, and it ate whales! Luckily for us, Megalodon died out 1.6 million years ago when the ocean became too cold for it.