Sharks belong to a family of fish that have skeletons made of cartilage, a tissue more flexible and lighter than bone. They breathe through a series of five to seven gill slits located on either side of their bodies. All sharks have multiple rows of teeth, and while they lose teeth on a regular basis, new teeth continue to grow in and replace those they lose.
Shark ‘skin’ is made up of a series of scales that act as an outer skeleton for easy movement and for saving energy in the water. The upper side of a shark is generally dark to blend in with the water from above and their undersides are white or lighter coloured to blend in with the lighter surface of the sea from below. This helps to camouflage them from predators and prey.
Sharks have adapted to living in a wide range of aquatic habitats at various temperatures. While some species inhabit shallow, coastal regions, others live in deep waters, on the ocean floor and in the open ocean. Some species, like the bull shark, are even known to swim in salt, fresh and brackish waters.