Deep-sea Darkness

Deep-sea Darkness

Imagine taking a trip to the bottom of the ocean. In water, light from the sun is quickly absorbed and scattered, so the deeper you sink, the darker it grows. Yet remarkable creatures swim all around you, well suited for life in the shadows.

Mid Ocean & Deep Reefs: Some fish manufacture their own light to stay inconspicuous in the dim waters of the mid-ocean. For example, using their glowing underbellies to match the faint sunlight filtering down, Hatchetfishes camouflage themselves against predators lurking below.

Along deep reefs, some fish light up another way: with their own private colonies of bioluminescent bacteria. For example, flashlight fish have brilliant, bacterial-filled pockets beneath their eyes that they use to communicate, confuse predators, and attract prey.

Into the Abyss: In the deep sea, almost all animals are bioluminescent. Some anglerfishes create light in two different ways: they have a modified fin spine topped with a lure

that pulses with bacterial light, while their chin sports tendrils filled with light-producing chemicals.

Marine biologists like those at The Field Museum and elsewhere discover new bioluminescent species with almost every voyage to the deep ocean. And as new technologies allow us to search even deeper, we are likely to discover many more.

For more information about the work of our marine biologists, check out our Venomous Fishes Gallery and our What the Fish podcasts.