Sharks, Skates, Rays, and Chimaeras

ISBN: 9781333208172 出版年：2016 页码：28 J R Thompson Stewart Springer Forgotten Books

Skates and rays have a more-or less flattened appearance, and all ex cept a few are either wholly or partially covered with denticles or Spines, which may be scattered irregularly or ar ranged in definite patterns. All skates and rays have five gill slits on each side of the lower surface of the head neck region. Chimaeras, like sharks, are fusi form in shape. Unlike sharks, they are usually smooth skinned, although a few denticles appear on the young and may persist in some adults, and they have only one external gill open ing on each side.