This is an expanded and edited version of an article that appeared in Yale Environment 360.

Imaizumi Hitoshi pushes back the silver quilting of a tent at the National Research Institute of Aquaculture in Shibushi, southern Japan, steps into the pitch-black interior, and switches on a flashlight. A tall, tube-shaped aquarium emerges from the darkness. Inside, slivers of reflected light flicker through the water: Japanese eel larvae, hatched just six days earlier. With huge black eyes set in skulllike heads and flat, transparent bodies, they look like tiny visitors from an alien world — which, in a sense, they are.