Sharks have been swimming the oceans of Earth for hundreds of millions of years, since before the time of the dinosaurs.
There are over 350 different species of sharks and they range in size from as small as a pencil case to as big as a school bus.
Swim For Your Life
Sharks belong to a class of fish that also includes rays and skates. All three are jawed fish with paired nostrils, paired fins and skeletons made of cartilage, the same type of tissue we have in our nose and ears.
Fish breathe through small slits on either side of their head called gills that extract oxygen from the water. Most fish have one pair of gills but sharks can have between five and seven.
Sharks have a higher demand for oxygen than other fish and many need to keep moving so that enough water passes over their gills for them to breathe. If these sharks stop swimming they can suffocate!
Extra Sharky Perception
It is generally accepted that humans have five senses: hearing, sight, smell, taste and touch. Sharks have seven! They are also able to sense vibration and electricity.
The lateral line, a system of fluid-filled tubes just under a shark’s skin, can sense vibrations in the water caused by currents or the movement of other animals.
In combination, all seven senses help sharks to be very effective hunters.
Man Bites Shark
Sharks are carnivorous predators that eat fish and other sea creatures. Some larger and more powerful sharks are feared as man-eaters, like the great white shark in the film Jaws.
In fact shark attacks on humans are very rare. You have a much greater chance of being struck by lightning or winning the lottery than being attacked by a shark. There were just four fatal shark attacks worldwide in 2005, two in Australia, one in America and one in Vanuatu.
On the other hand, humans have hunted sharks to the point that the survival of some species is threatened. Humans catch 100 million sharks per year and most end up in shark fin soup or battered and fried at your local fish and chip shop.
Did you know?
- A group of sharks is called a shiver.
- Some sharks lay eggs, others give birth to live pups.
- The largest fish is the world is the Whale Shark, which can grow up to 16 metres long.