Rajiformes

Rajiformes is one of the four orders in the clade Batomorphi, often referred to as the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule ("mermaid's purse").

== Characteristics == Rajoids typically have a dorsoventrally flattened body. The snout is slender and pointed and the wide mouth, often covered with a fleshy nasal flap, is on the underside of the head. The eyes and well-developed spiracles are located on the top of the head. In most species, the spiracles are large and are the main means of drawing water in for respiration. There is no nictitating membrane and the cornea is continuous, with the skin surrounding the eyes. The gill slits are on the ventral surface just behind the head. The front few vertebrae are fused into a synarcual and this either articulates with the bones of the well-developed pectoral girdle or is fused to them, the suprascapulae uniting above the vertebral column. Most species have enlarged, thornlike dermal denticles on their skin, often with a row of large denticles along the spine.