Skates normally occur in deeper waters, but the thornback Dipturus lemrprieri, and Whitley’s or Wedgenose Skate Dipturus whitleyi are common in the Derwent estuary, and are regularly seen in very shallow waters. Skates can be distinguished from rays as they have two small dorsal fins near the end of their tail. The eagle ray Myliobatis australis is the most common ray in the Derwent estuary, and they often swim into ankle deep water, so shallow that their wings protrude from the waters surface. Skates, rays and sharks are all closely related to each other, and are cartilaginous fish – meaning their skeleton is made from cartilage rather than bone. Skates and rays often have patterned skin which provides camouflage against sandy sediments. They glide over the sediment feeding on crabs and molluscs and shallow burrowing animals. Skates and rays are also protected in Shark Refuge Area’s, meaning that the taking of sharks, skates or rays is prohibited within the Derwent Shark Refuge Area.