Basics of Sharks
- Sharks have roamed our seas for more than 400 million years, which means they inhabited the earth for nearly 200 million years before dinosaurs.
- Sharks are fish with skeletons made of cartilage instead of bone, but sharks’ slow growth and late maturity mean they have more in common with sea turtles and marine mammals than bony fish such as flounder or tuna.
- Sharks are a remarkably diverse group of fish. They range from less than a metre to 20 metres in length; they are found in most coastal regions but also in the deep ocean and even in fresh water. Some sharks lay eggs, but most give birth to live young. Most are top predators while a few feed on plankton. Sharks in turn are preyed upon by other sharks and sometimes killer whales.
- The term ‘shark’ often refers not only to shark species but also to the closely related rays and skates, as well as the oft-overlooked chimaeras (rat, rabbit and elephant fish).Collectively these cartilaginous species are known as chondrichthyan fish (forming Class Chondrichthyes).
Shark’s teeth
There is something unique about sharks’ teeth! A shark without teeth could not survive; it would starve. Therefore, unlike many other animals like dogs and canines, sharks continuously get new teeth to replace those that fall out. A shark’s mouth generally contains five or more rows of teeth, one behind the other. All rows, with the exception of the first, lay flat in the animal’s mouth. The next row rises up to replace any teeth that have fallen out or were broken. Sharks always make new teeth and have always spare rows of teeth. Sharks’ teeth are adapted to what they eat. Unlike humans, sharks do not chew. They are not omnivores, but carnivores. They use their teeth to grasp prey and, if needed, tear the prey into smaller chunks they can swallow. Most shark teeth are very sharp. Sharks’ jaws are powerful and the sharp teeth are capable of cutting through bone and even thin steel chains.
Shark teeth vary from being ferocious-looking curved spikes to flat triangular points, to points that are so small that they are not used for anything at all. The larger sharks, like the great white and the tiger shark, have triangular teeth with jagged edges. This helps to keep hold of large fish and animals so as to tear chunks of meat from their bodies or slice through a turtle’s shell. A sand tiger’s teeth, on the other hand, are long and narrow which make them look frightening, but in fact this type of shark is not very aggressive. The shape of its teeth is ideal for grabbing hold of slippery prey, like fish and squid. However, the whale shark, one of the biggest sharks on earth, has very small teeth. Whale sharks don’t use their teeth for biting because they simply filter their food.
