狼鳗的外部形态、消化系统和生殖系统的观察

Morphological characteristics, digestive system and reproductive system of the wolf-eel (Anarrhichthys ocellatus)

中文关键词: 狼鳗  外部形态  可数可量性状  消化系统  生殖系统

英文关键词: Anarrhichthys ocellatus  Morphometic characters  Meristic and metric characters  Digestive system  Reproductive system

中文摘要:

      采用观察、测量、解剖和拍照的方法，对狼鳗(Anarrhichthys ocellatus)的外部形态、可数可量性状及消化系统、生殖系统进行研究，并描述了狼鳗的相关特征。结果显示，狼鳗体型为鳗形，整体呈黑色或灰黑色，头部、背部及背鳍鳍条上有若干似眼睛的黑色圆斑，体表无鳞。背鳍鳍条数为232~267，胸鳍鳍条数为15~22，臀鳍鳍条数为189~220，无腹鳍，背鳍和臀鳍因与尾鳍相连而无明显区分界限，侧线左右各2条，均不完整，雄性侧线点明显，而雌性侧线点不明显。上排侧线点数为18~25，下排侧线点数为76~85。上鳃耙数为49~70，下鳃耙数为55~73，脊椎骨数为232~271。全长/体长线性相关性最好，雌、雄差异很小，稳定性最好。头长/吻长、头长/眼径、体长/肠长的变化范围较大，雌、雄间差异较大，线性相关性差，可以作为区分狼鳗雌、雄的重要特征；狼鳗体重与体长关系：W=0.0337Sl2.4798(R2=0.9992)，雌性：W=0.0326Sl2.4864(R2=0.9990)，雄性：W= 0.0359Sl2.4672 (R2=0.9995)。消化系统由消化道和消化腺构成，口咽腔大，具颌齿，无腭齿、犁齿，咽喉齿发达；胃大，呈“Ⅰ”型，无幽门盲囊；肠短粗，比肠长为0.45；相关性状及特征显示狼鳗为肉食性鱼类。雌雄异体，卵巢(Ⅲ~Ⅳ)呈椭圆形，粉红色，左右对称，精巢(Ⅲ~Ⅳ)呈黄白色，“Y”形。

英文摘要:

      We observed, measured, anatomized, and photographed the external shape, meristic and metric characters, digestive system, and reproductive system of Anarrhichthys ocellatus. The results are as follows: the body type of the A. ocellatus is anguilliform, the skin color is black or rubricans without any mackerel scales, and there are a number of dollar spot-like eyes on the head, back, and dorsal fin. The number of spots on the dorsal fin, pectoral fin and anal fin were 232~267, 15~22, and 189~220, respectively. A. ocellatus has no ventral fin, and the tail fin is linked to the dorsal fin and pectoral fin and cannot be distinguished. There are two incomplete lateral lines on each side, the upper is 18–25 and the lower is 76~85. The female lateral line is distinct. However, that of the male is not. A. ocellatus also has no pyloric caeca, and the number of upward gill rakers, downward gill rakers, and vertebrae are 49~70, 55~73, and 232~271, respectively. Besides, the magnitude of variation in the total length/standard length is small, with little difference between females and males. The values of the head length/proboscis length, head length/eye diameter, and standard length/intestine length not only vary largely, but present poor linear correlation, with great differences between females and males. Therefore, the females and males can be distinguished. The relationship between weight and length: W = 0.0337Sl2.4798 (R2 = 0.9992), for females, W = 0.0326Sl2.486 (R2 = 0.9990); and for males, W = 0.0359Sl2.4672 (R2 = 0.9995). The digestive system consists of the digestive tract and digestive glands, and the oropharyngeal cavity is large; A. ocellatus has jaw teeth, without cavities and plow teeth, the pharyngeal teeth are well-developed, the stomach is “I”-shaped and large. The intestines are wide and short, and the ratio of intestine length/total length is 0.45. The related traits and characteristics show that the A. ocellatus is carnivorous and hermaphroditic. The ovaries (Ⅲ~Ⅳ) are elliptical, pink, and left right symmetrical. The testes (Ⅲ~Ⅳ) are “Y”-shaped and pink.