Cartilaginous fishes

Scientific name : Chondrichthyes

The cartilaginous fishes (Chondrichthyes) comprises of more than 1100 different species, such as sharks, rays and chimaeras.
What really makes the difference in these creatures is their skeleton, entirely made up of cartilage; this is the reason behind their scientific name.
More, all the cartilaginous fishes have a well-developed electroceptive sense, which lets them perceive electric fields in the sea.
Their skin is covered in placoid scales, looking like denticles, often oriented in the same direction; this lets water flow easier over them, making them good swimmers.