The Transparent Larval Stage of a Developing Eel

Hashem Al-Ghaili of Science Nature posted a really informative video essay about the leptocephalus — the fascinating larval stage of developing eels. During this stage, the nacent eels are completely transparent with very simple innards and zero blood cells.

Their bodies contain jelly-like substances on the inside …their body organs are extremely small and they only possess a simple tube for a gut.