Bioluminescence in the ocean: origins of biological, chemical, and ecological diversity

Reviews the ecological functions of marine bioluminescence, organising them into defence, offence and communication, and examines why the same chemistry serves such different purposes.

Studied in

Animalia, Bacteria

Sample size

review

Light is used defensively — as startle, as a smokescreen, as counterillumination, and to summon a predator’s own predators — offensively as a lure or a searchlight, and communicatively for mating and species recognition. Which function dominates varies by depth and by group.

• Function is inferred from context and behaviour in many species, and directly tested in relatively few.
• Deep-sea observation is limited by what submersibles and traps can see and catch.

• Bioluminescence

  Making light is not one invention. It arose independently something like forty separate times, using several chemically unrelated light-producing molecules — and in the deep ocean most animals in many groups can do it.

• Counterillumination

  Midwater animals cancel their own silhouette by lighting their undersides to match the daylight filtering down — and they adjust the brightness as the light above changes.

• Counterillumination

  The strategy only works in a narrow band of the ocean — deep enough that a silhouette is what gives you away, shallow enough that there is still light above to match. Below that, there is nothing to match.