Sharks! Big, bold, scary beasts of the ocean. They're frightening alright, but how much do you actually know about sharks?
Sharks are a group of fish identified by a cartilaginous skeleton, five to seven gill slits on the sides of the head and pectoral fins that are not fused to the head. Modern sharks are the sister group to the rays, I know right, who would have thought a Stingray and a Great White shark were related?! The earliest known sharks date back to more than 420 million years ago with the Megalodon, the ancestor of the modern Great White shark. A Megalodon was a huge shark, the size of a whale, that swam the oceans during the time of the dinosaurs, but is now classified as extinct (which is a good thing for surfers!)
Since then, sharks have diversified into over 470 species. They range in size from the small dwarf Lantern shark, a deep sea species of only 17 centimetres in length, to the Whale shark, the largest fish in the world; which reaches approximately 12 metres in length. Sharks are found in all seas and are common to depths of 2,000 metres. They generally do not live in freshwater, although there are a few known exceptions, such as the Bull shark and the River shark, which can survive and are found in both seawater and freshwater, but not in the UK so don't worry! Citizens of Australia and the USA may find sharks and crocodiles in their rivers though! The most dangerous and scary part of sharks is their teeth and guess what? They have several sets of replaceable teeth! Best to stay away I think.
Well-known species such as the Great White shark, Tiger shark, Blue shark, Mako shark, and the Hammerhead shark are apex predators, meaning that they are at the top of their underwater food chains and will eat pretty much anything that gets in their way. However, not all sharks are great scary monsters, many shark populations are threatened by human activities such as fishing and you can actually swim with some sharks and even cuddle them like dolphins. I've been swimming with dolphins before and really enjoyed it, but I think I’d still be too scared to do that with sharks!