Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. They are carnivorous, feeding mostly on smaller fish and crustaceans. They have flat pectoral fins continuous with their head, two dorsal fins and a short, spineless tail. There are more than 200 described species in 25 genera.
Skates are bottom-dwelling and are found throughout the world from continental shelves down to the abyssal zone. They are oviparous fishes, laying eggs in a case known as a mermaid's purse. It is thought that egg-laying in skates is an evolutionary reversal, that is, skates are descended from ovoviviparous ancestors.
The common skate, Dipturus batis, is the largest found in British waters. It has a long, pointed snout. However, the most common skate in British seas is the thornback ray, Raja clavata. They are frequently caught by trawling. Common skate and white skate are assessed as Critically Endangered by IUCN (World Conservation Union) and the fish is listed by the Marine Conservation Society as a "fish to avoid".
The big skate, Raja binoculata, and longnose skate, Raja rhina, are among the most common found in the Pacific Ocean, ranging from southern Alaska to northern Mexico. The big skate , also known as the Pacific great skate, reaches a width of 2.4m (8 ft.) across.