骨鳞

真骨鱼类所特有的鳞.骨鳞柔软扁薄，富有弹性，一般为圆形或亚圆形，前端插入鳞囊内，后端翘起，压叠在后一鳞片的前端，呈覆瓦状排列.鳞片由两层构成：上层是骨质层，比较硬脆.下层是纤维层，比较柔韧.鳞随鱼体增长而增大、增厚.鳞片生长的特点是，骨质层一圈一圈的扩大，构成若干同心环纹；纤维层一片片的向外周 铺展.这样生长的结果，鳞片既增大又增厚.一年之中，鱼体增重速度 快慢相间，使骨鳞上的环纹疏密交替， 周而复始，构成 年轮.据此可推测鱼类年龄.根据骨鳞后部的形态，可分为 圆鳞和 栉鳞两种.圆鳞 后缘光滑，如 鲱形目、 鲤形目的 鱼鳞；栉鳞后缘栉齿状，如 鲈形目、 鲽形目的鱼鳞. 大黄鱼、和 石斑鱼（Ｅｐｉｎｅｐｈｅｌｕｓ）既有圆鳞又有栉鳞.Teleostei specific scales. Bian soft bone scales thin, flexible, generally circular or sub-round, front-end insert scales capsule, back tilt, pressure scales stacked in front of the latter, was covered tile -like arrangement. scales by two components: the upper bone layer is relatively hard and brittle. lower fiber layer is relatively flexible. scales of fish growth with the increased thickness. scales are characterized by growth, bone-layer lap ring expansion to form a number of concentric ring pattern; fiber layer of a film spreading outward weeks. This growth results not only increase the scale thickened again. one year, fish weight gain rate of speed and white, so that scales on the bone alternating ring pattern density, cycle, composition rings. Accordingly, it can be assumed the age of fish. According to scale back the shape of bone can be divided into two kinds of circular scales and ctenoid. circular smooth posterior edge of scales, such as the Clupeiformes , carp-shaped the purpose of scale; ctenoid dentate posterior edge comb, such as Perciformes, Pleuronectiformes the purpose of fish scales. large yellow croaker, and grouper (Epinephelus) both have ctenoid round scales.