Ostracods are just one example of a much bigger, stranger phenomenon: living creatures that make their own light. This page explains what bioluminescence actually is, where else in the world you can find it, and what makes the Ostracods of Bonaire special.
What is bioluminescence?
Bioluminescence is the production and emission of light by a living organism, through a chemical reaction inside its own body. It’s essentially a cold, biological form of light: unlike a lightbulb, almost none of the energy is lost as heat.
The reaction is usually driven by a light-emitting molecule called luciferin, combined with an enzyme called luciferase (or a related protein). When the two interact, typically in the presence of oxygen, energy is released as a photon of visible light. Different species use slightly different chemistry, which is why bioluminescence can appear in different colors, though blue-green is by far the most common in the ocean.
Why do animals glow?
Bioluminescence isn’t just a curiosity, it’s a survival tool. Depending on the species, glowing can serve very different purposes:
- Attracting a mate — as with Ostracods, light can be used as a courtship signal in complete darkness.
- Luring prey — deep-sea anglerfish dangle a glowing lure to draw curious fish within striking distance.
- Startling or confusing predators — a sudden flash of light can buy a small animal a crucial second to escape.
- Camouflage — some deep-sea species glow on their undersides to blend in with faint light from above, a trick called counter-illumination.
Bioluminescence around the world
Ostracods are one striking example of marine bioluminescence, but similar phenomena occur in many places, on land and at sea:
- Fireflies use bioluminescence in exactly the same way many marine Ostracods do: to signal to potential mates after dark.
- Bioluminescent bays, such as those found in Puerto Rico and the Maldives, glow from huge concentrations of microscopic dinoflagellates that light up when the water is disturbed.
- Deep-sea anglerfish and jellyfish live in near-total darkness, where producing their own light is often the only way to see, hunt, or be seen.
- Glow worms, found in caves in New Zealand and Australia, use light to lure flying insects into sticky silk threads.
What makes Ostracods different
Most bioluminescent dinoflagellates glow whenever the water around them is disturbed, by a wave, a paddle, or a swimming diver. Ostracods work differently: the males actively choreograph short, precise pulses of light in a deliberate courtship display, released into the water in a rising, glowing trail. It’s closer to a firefly’s flash pattern than to the diffuse sparkle of disturbed plankton.
Want to know more about the animal itself? Read everything about Ostracods, or check the calendar to find out when you have the best chance of seeing them on Bonaire.