Some sharks can change shape. Swell sharks inflate their bodies with water or air to make themselves bigger and rounder.
The insides of the sharksintestines are spiral shaped. Because of this, some sharks have spiral-shaped droppings.
Some sharks are so flexible, they can bend right around and touch their tails with their snouts.
Shark skin is so rough that in the past it was used to make a type of sandpaper, called shagreen.
Without their fins, sharks wouldn’t be able to stay the right way up. They’d roll over in the water.
Most sharks never close their eyes. Some have special see-through eyelids that protect their eyes without cutting out light. Others just roll their eyes up into their head to protect them.
Although sharks can hear sound, they rarely make a noise.
A shark can sense a turtle, octopus or other prey from up to 20m away.
In one experiment, a scientist plugged one of a shark's nostrils. It swam around in a circle.
Shark brains aren’t round like a human's; they are long and narrow.
If sharks don’t keep on swimming they sink to the seabed.
A typical shark has several hundred teeth at any one time.
Shark jaws are strong enough to bite a turtle in half.
In Australia in 1935, a tiger shark vomited up a human arm. The shark had not killed anyone but had scavenged the arm after a murder victim had been cut up with a knife and thrown into sea.
As a way to put off attackers (or to remove indigestible stomach content), sharks can turn their stomachs inside out and vomit up their latest meal. Some predators eat the vomit instead of the shark.
The electroreception in sharks is so sensitive that they often mistake the minute electrical charge caused by rusting boat hulls for prey.
The ancient Greek scientist and writer Aristotle studied and wrote about how sharks mate over 2300 years ago.
In sand tiger sharks and several other species, the biggest, strongest pups eat the others while still inside their mother’s body.
Sharks never stop growing; when they reach adulthood, they just slow down.
Epaulette sharks are often found in rock pools. They can move from one pool to another across dry land, by dragging themselves with their strong pectoral fins.
A whale shark's skin is around 10 cm thick, making it the thickest skin in the world.
In 2004, while snorkelling in Australia, Luke Tresoglavic was bitten by a small wobbegong that refused to let go. He had to swim to the shore and drive to get help with the shark still attached to his leg.
You have a greater chance of being struck by lightning, drowning in a bathtub, fatally falling down stairs, or dying from a bee sting than being killed by a shark.
Sharks have been around longer than trees!
Until the late 16th century sharks were usually referred to in the English language as sea-dogs. The name "Shark" first came into use around the late 1560s to refer to the large sharks of the Caribbean Sea.
Some sharks, if inverted, enter a natural state of temporary paralysis called tonic immobility. Researchers use this condition for handling sharks safely.
The name shark may have originated from the Mayan word for shark, xoc, pronounced "shock" or "shawk".
The teeth of carnivorous sharks are not attached to the jaw, but embedded in their flesh. In many species, teeth are constantly replaced throughout the shark's life.
Even though the basking shark is considered to be slow and very large, it can actually breach the water, i.e. jump fully out, as some whales do.
Despite the common myth that sharks are largely instinct-driven "eating machines", recent studies have indicated that many species possess powerful problem-solving skills, social complexity and curiosity.
That sharks are not known to bite humans as often as people think.
