They glide through the oceans with characteristic grace. Remainders of our ancient past – they dive and rise from the deep oceans to the shallows like no other creature in the sea. They are the world’s biggest living fish - Sharks.
These gigantic fishes usually grow to about 40 ft. long. The largest is the Whale Shark. It is believed that the pre-historic shark reached 80 ft. long and weighed about 70 tons. It consumed any creature that would fit in its nearly 10 ft. wide mouth. Unlike humans, sharks have an endless supply of teeth. Most sharks loose their teeth while hunting, and are replaced regularly.
Shark bodies are evolved to give them speed . The fastest known shark – the Short Fin Mako shark can reach speeds of up to 46 miles/hr. This speed is mainly because of its hydrodynamic design. Shark skin also contains V-shape placoid scales which allow the water to move smoothly past the skin, reducing friction. Sharks also have skeletons made of cartilage, which is lighter than bone and so sharks get rid of the extra weight.
Most sharks lay live young ones called pups which stay with the mother for approximately 1 year, where they learn predation skills. In some sharks like Sand Tiger shark, pups compete with their siblings when they are in the womb and the fittest one comes out. Sharks have sharp eyes with an amazing vision even in dark and can visualize the colors . This is due to the presence of Tapetum, a reflective tissue.
Every year, around 100 million sharks are slaughtered worldwide mostly for shark fin trade. The sharks are killed and their dorsal fins are removed, which are then sold at high prices mainly in India. Some species like the Spiny dogfish and Porbeagle are killed primarily for their meat . Because of the high demand of shark fins, some species of shark populations have declined to 70 %, causing a ripple effect in marine ecosystems.
However, measures are being taken to protect sharks, with the many countries strictly banning unsustainable shark fishing. Through integrated international conservation practices, the extinction of sharks may be prevented, allowing the creatures to swim in all their power and grace, surviving for many generations to come.
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