Essay about sharks
Sharks belong to a group of fish called ‘elasmobranch’. Their existence dates back to 420 million years. They are a different type of fish that are made of cartilaginous tissues and not bones. This is the reason that it is hard for their fossils. There are many types of sharks. They are generally present in seas with ‘bull shark’ and ‘river shark’ as exceptions. These two types of sharks are found both in freshwater and salty water. The sizes of sharks vary drastically. They have many rows of replacement teeth and they lose around 30,000 teeth during their lifetime. They are on the top of their undersea food chain. Most of them are carnivorous. They balance the marine ecosystem.
Sharks move very fast so that the water passes over the gills to get the required oxygen to breathe. They have sharp eyesight and a sharp sense of hearing. The lifespan of most of the species of sharks vary between 20-30 years. They are cold-blooded animals. They are migratory in nature and travel long distances in search of food sources. Not all sharks attack humans. The huge predator sharks such as tiger sharks, bull sharks, and the great white sharks sometimes attack humans. . They are afraid of killer whales. Sharks are survivors of five mass extinctions.
Unlike other sharks that live longer in captivity, the ‘great white sharks’ are unable to withstand aquarium conditions and die in captivity. Shark fins are a delicacy in Asia and they are hunted for that purpose. They also are caught in fishing gear. Global warming and plastic pollution are the reasons for the decline in shark population. They are under serious threat due to human activities.