Skates are rounded to diamond-shaped in form. They have large pectoral fins extending from or nearly from the snout to the base of the slender tail, and some have sharp “noses” produced by a cranial projection, the rostral cartilage. Skates may be solid coloured or patterned. Most have spiny or thornlike structures on the upper surface, and some have weak electrical organs in the tail. Typical skates (Rajidae), the majority of the living forms, have two dorsal fins on the tail; the Arynchobatidae have one, and the Anacanthobatidae have none. The mouth and gill openings of all skates are situated on the underside of the body, and all, so far as is known, lay eggs. The eggs, the so-called mermaid's purses often found on beaches, are oblong and protected by leathery cases.

Skates vary in size. The little, or hedgehog, skate (Raja erinacea) of the western Atlantic, for example, is adult at a length of 50 cm (20 inches) or less. In contrast, the big skate (R. binoculata) of the North American Pacific may be 2.5 m long. Skates are innocuous bottom dwellers, often found lying partly buried. They swim with a graceful undulating movement of their pectoral fins. Skates feed on mollusks, crustaceans, and fishes, trapping active prey by dropping down on it from above. Skates are edible, the “wings” being the portion consumed.