A shark has a cone-shaped head with eyes on either side, and a long snout. Its body is covered by smooth skin that can be coloured in many different shades. It has rows of sharp teeth in the gums and they are replaceable with new rows throughout their life. The caudal fin is asymmetrical and it has a complex dermal corset made up of flexible collagenous fibres providing protection for its skin. Sharks do not have an operculum to cover their gills