![]() ![]() The chunks of food that a shark swallows end up in its stomach, where they are digested. So they bite their prey and jerk it around so they can pull off a chunk to swallow. In its lifetime, a shark can lose and regrow as many as 30,000 teeth.Įven with all those teeth, though, sharks can not chew. Sharks eat so violently they often break a few teeth, so new teeth grow continuously in a groove just inside the mouth and move forward from inside the mouth on "conveyor belts" formed by the skin which they are attached to. Their teeth are constantly replaced throughout their lives. Sharks come in many different shapes and sizes, but most are long and thin (also called streamlined), with really strong jaws. ![]() For this reason shark teeth are one of the most common fossils.Ĭharacteristics Prehistoric sharks, like their modern descendants, would grow and shed many thousands of teeth over their lifetime. While sharks have skeletons made of soft cartilage that can fall apart before fossilizing, their teeth are harder and easily fossilized. Much of what we understand about prehistoric sharks comes from the study of their fossils. Megalodon died out 1.6 million years ago. It was 18 meters long, twice as long as the closely-related great white shark, and it ate whales. Just a few million years ago, a giant shark called Megalodon swam in the seas. Most sharks are cold-blooded but some, like the great white shark and the mako shark are partially warm-blooded. Some common kinds of shark are the hammerhead shark, the great white shark, the tiger shark, and the mako shark. However, a recent study shows that sharks emit a low growl from their throats which resonates through their scales. It is widely believed that sharks are "silent killers". This is the whale shark, the largest fish in the world. However, the largest shark eats krill, like whales. Most sharks are predators: they hunt and eat fish, marine mammals, and other sea creatures. ![]() Fossils show that sharks have been around for 420 million years, since the early Silurian. There are more than 350 different kinds of sharks, such as the great white and whale sharks. Cartilaginous fish also include skates and rays. Cartilage is tough, rubbery material which is less rigid than bone. Like other Chondrichthyes, they have skeletons made of cartilage instead of bone. This superorder is also known by its scientific name Selachimorpha. ![]()
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