Batoidea is a superorder of cartilaginous fish commonly known as batoids or rays, but it also includes the skates and sawfishes. Approximately 560 species are described in thirteen families. Batoids are in the fish subclass Elasmobranchii along with sharks, as they are closely related. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.