Studies on diet of Anguilloid leptocephalus larvae

对鳗科（Congridae）、海鳗科（Muraenidae）、海鳗科（Muraenesoporiae）、网口鳗科（Nettastomatidae）和蛇鳗科（Ophichthidae）8种鳗鱼共585尾的肠道内容物进行了研究。幼体属于细头期（566只）和早期变态期（19只）。可见的肠道内容物被确认在246个人的8个物种，无论发育阶段。实验结果表明，在猕猴的肠道内可见透明物（0.4 ~ 1.2mm）和不透明物（20 ~ 380 μ m）。从形态特征上看，前者为幼虫房，后者为浮游动物粪球。此外，肠道中的大部分粪便颗粒被鉴定为Oikopleuridlarvacean的粪便颗粒。许多其他浮游植物或浮游动物，在周围的沃茨中与细头鱼一起被发现，可能是合适大小的食物，但在任何细头鱼的肠道中都没有发现。根据幼虫室在几种细头虫幼虫食物中的重要性，提出细头虫的特殊的、大的、尖牙状的牙齿用于进食，并进化成刺穿和抓住幼虫的粘液室。

Gut contents of 585 letocephali comprising eight species of eels were examined from five families (Congridae, Muraenidae, Muraenesocidae, Nettastomatidae, and Ophichthidae). The larvae belonged leptocephalus(566 specimens)and the early metamorphic stage(19 specimens). Visible gut contents were recognized in 246 individuals among the eight species, regardless of developomental stage. Two kinds of visible objects, transparent(0.4 to1.2mm)and opaaque(20to380mum), were found in the gut of letocephali. From their morphological characteristics, the former and the latter were identified as larvacean houses and zooplankton fecal pellets, respectively. Furthermore, most fecal pellets in the gut were identified as oikopleurid larvacean's fecal pellets. No trace of the many other phytoplankton or zooplankton, which were found with leptocephali in the ambient waters and could be suitable-size food, was found in the gut of any leptocephalus. On the basis of the importance of larvacean houses in the diet of serveral species of leptocephalus larvae, it is proposed that the peculiar, large, fang-like teeth of leptocephali are used for feeding, and evolved to pierce and grasp the mucous houses of larvaceans.