Characterization of triglycerides during early development of the Japanese eel (Anguilla japonica)

Japanese eels store lipids in the peritoneal cavity at the glass eel stage. These lipids are presumed to be consumed as an energy source during migration from oceanic metamorphosing sites to coastal Japan. In this study we investigated the distribution and amount of triglyceride in vivo using artificially bred Japanese eel larvae. Triglycerides accumulated in vivo from the early larval stage onward, until they reached a peak volume in fully grown leptocephali, and subsequently gradually decreased during metamorphosis. Furthermore, during the late metamorphic stages of the artificially bred glass eel, triglycerides were stored mainly in the peritoneal cavity, as in wild glass eels. These observations point to a strategy that the Japanese eels use in consuming the triglycerides derived from leptocephali during metamorphosis (when they do not feed) as a source of energy.