5 Jaw-dropping facts about sharks

Sharks are magnificent creatures and one of few living connections to the time when dinosaurs walked the earth. With all those teeth and Steven Spielberg's Jaws forever in the back of our minds however, we sometimes need reminding just how magnificent they are.
 

Sharks are everywhere. Well, in every ocean at least. Amazingly, they can be found in all seven of the world’s oceans.

There are over 400 species of the fish-with-teeth and some are found in mixed salt and freshwater environments like river estuaries. In 2013 a shark was even spotted in a river in Essex.

Both. Many sharks are oviparous, which means they produce their young by laying a cluster of eggs. Others are viviparous and give birth to a small litter of pups.

Incredibly, some species actually do both. These sharks are ovoviviparous, meaning they produce eggs, which remain inside the female for the gestation period until they hatch.

In all cases, the new pups are left to fend for themselves from an early age while mum heads back into the ocean.

Sharks cut a lonesome figure in the world’s oceans. It has been difficult for researchers to study how sharks communicate with one another, as they don’t live in shoals.

However, it is understood that sharks express agitation by presenting their bodies in particular ways. Watch out for arched backs, sharp movements and lowered pectoral fins. In shallow waters they will swim up and down, touching the ocean floor to signal distress.

Most of us know that sharks can have up to three rows of teeth. But did you know that sharks don’t have bones?

Sharks are known as cartilaginous fish, meaning their bodies are structured by cartilage instead. Beneath a shark’s skin is a network of ‘canals’ filled with fluid that can detect changes in water pressure—that’s how they detect their prey!

For every human killed by a shark, 2 million sharks are killed by humans. Researchers estimate that 100 million sharks die each year as a result of human intervention.

The causes of such large fatalities range from accidental ‘bycatch’ in commercial fishing nets, to illegal practices like ‘finning’, where the dorsal fin is removed for traditional medicines and soup.