Bioluminescence In The Ocean
If you have ever gone to the ocean at night, you may have been lucky enough to see it light up. Flashes of blue illuminate the waves breaking on the shore—sparkles in the sea that almost don’t seem natural.
Though we only see it on rare occasions, the ocean is FULL of organisms that are bioluminescent—particularly in the deep sea.
What is bioluminescence?
Quite simply, it is a chemical reaction within the organism. A type of molecule called luciferin, when combined with oxygen, will produce photons—or light.
Bioluminescence is not rare in the ocean—over 1,500 species possess the ability to light up, from bacteria to algae to fish, even some sharks.
Light can’t penetrate the deep ocean, so being able to produce light has many advantages for organisms. Bioluminescence has evolved multiples times in different lineages of marine species—for feeding (attracting prey), attracting mates and even to avoid predation.
Some fish exhibit counter-illumination, where the belly of the fish lights up to match the light coming down from the sea surface, allowing it to blend in and avoid predators that are below it. Meanwhile, the top of the fish stays dark to blend in with the darkness below and hide from predators above.
You may have seen the freaky looking anglerfish before, with a lure of light that it dangles in front of its face. This lure is full of bioluminescent bacteria, and the fish used this bright lure to attract its prey.
But not all bioluminescence occurs 1,000 meters below the surface. A type of plankton called dinoflagellate, which is also responsible for the ‘red tides’ (algal blooms) we see at certain times of the year, can be bioluminescent. Mechanical action, from waves or boats moving, can stir up the water enough to cause these little creatures to release light. There is no guarantee…but next time you see a red tide in the ocean during the day, camp out on the beach and you may be able to see some glowing waves that night.
Image: Anna Talken