Shark
A general term for fish belonging to the subclass Elasmobranchii of the class Chondrichthyes whose gill slits open on the sides of their bodies.
Their origin dates back 400 million years, and although there have been some morphological changes, their basic body structure remains almost the same as that of ancient species.
They are distributed throughout oceans around the world, with approximately 500 species currently in existence. Some species have expanded into the deep sea and freshwater areas.
Rays are also fish in the subclass Elasmobranchii, but unlike sharks, they are distinguished by having gill slits that open on the underside.
Their noses are equipped with electrical sensors called Lorenzini bottles, which are filled with a jelly-like substance, and can pick up weak electrical signals generated by the movement of prey or external enemies.
