Bioluminescence is light from a chemical reaction inside an organism or its bacterial partner. In the deep sea it can provide camouflage through counterillumination, attract mates or prey, expose attackers and confuse predators.
Three things to know
- Common color
- Blue-green
- These wavelengths travel farthest through seawater.
- Reaction
- Luciferin chemistry
- Light-producing molecules and enzymes vary among lineages.
- Many origins
- Evolved repeatedly
- Bioluminescence is not one inherited system shared by all glowing life.
Light made by chemistry
A light-emitting molecule is oxidized in a controlled reaction, often assisted by an enzyme. The process releases little heat compared with an incandescent source. Some animals produce the components themselves; others culture luminous bacteria in specialized organs.
Camouflage by adding light
An animal viewed from below can appear as a dark silhouette against faint downwelling light. Photophores on its underside can match that background and erase the outline. This counterillumination is especially important in the twilight zone.
Signals, traps and alarms
Anglerfishes use luminous lures, while some squid eject glowing material. Other organisms flash when attacked, potentially startling the predator or attracting a larger predator to the disturbance—the burglar-alarm hypothesis. The same technology serves very different ecological jobs.
What people usually ask
Is every deep-sea animal bioluminescent?
No, but the ability is widespread across many animal and microbial groups.
Why is red bioluminescence rare?
Red light is absorbed quickly in seawater and many deep animals cannot see it, though a few species use or detect red wavelengths.
Here’s where the answer came from
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