Flashlight Fish main content.

Flashlight Fish

Part of the Creatures of Light exhibition.

A stylized visualization from the side of a grayish-black fish with a white half-circle under the eye and string of white dots from the eye, down the spine area to the tail.
© AMNH/E. Grosch

Bioluminescence has evolved multiple times in the ocean, and marine animals have developed an astonishing array of systems for emitting light. Some manufacture their own light-making chemicals, luciferin and luciferase. Many more get their luciferin from the organisms they eat.

Some squids and fishes light up in another way: with their own private colony of bioluminescent bacteria. In symbiotic relationships that evolved long ago, these animals have developed special organs for supporting glowing bacteria and making use of their light. For example, flashlight fish have pockets under their eyes that are filled with bioluminescent bacteria.

Creatures of Light features a display of live flashlight fish, as well as a separate display of live bioluminescent bacteria.

Bioluminescent bacteria are widespread in the ocean—an average tablespoon of seawater contains just a few. They can float freely, or settle down inside other organisms. The species shown in the exhibition lives in the light organs of pinecone fishes and bobtail squids.