Lights On – 10 Fascinating Bioluminescent Creatures
Some people hear the song “You Light Up My Life” (usually sung by Debbie Boone, but also performed by many other artists) and they think of their loved ones. Literalists, however, hear the familiar tune and think of bioluminescent animals like glowworms and fireflies. One can only wonder if the song was actually written by a glowworm or bioluminescent jellyfish for the apple of its eye. The following list details some of the animals that glow, be they far below the sea surface, flying around in the summer, or even the worms and fungi that glow in the pale light of caves. The glow is produced via a variety of chemical reactions with water or air. The creatures use their light for an interesting array of purposes. Some animals, such as the anglerfish, trap prey, and others use their lights as a warning of predators. It works both ways. Let’s take a look at the animals that glow from inside.
10. Vibrio Harveyi Bacteria
The bacteria called Vibrio harveyi floats in the ocean and are mainly thought to reside near the tropics. V. Harveyi are the likely cause of the effect known as the milky sea, the world’s largest bioluminescent area, which is roughly the size of Connecticut. This effect was largely thought as a myth (even mentioned by Jules Verne in 20,000 Leagues Under the Sea) until being verified by scientists in 2005. Perhaps the most unusual aspect of V. Harveyi is that they seem to communicate with each other via a process called quorum-sensing. This process of cell-to-cell communication which regulates gene expression based on population density is produced by the release of an auto inducer. In addition to luminescence, the auto inducer release regulates production of antibiotic and biofilm. Because of the auto inducer production, V. Harveyi are being studied for biotechnological applications that include incorporation into novel antimicrobials.
From bacteria, we move to marine plankton called dinoflagellates. Some of these microorganisms glow with bioluminescence when disturbed. Perhaps the most well known example of this light can be found in Mosquito Bay, which is off the coast of the Puerto Rican island of Vieques. The bay, also known as The Bio Bay, has the perfect combination of elements for the dinoflagellates (in this case, the species known as Pyrodinium bahamense) to show off their blue glow. The bay is surrounded by red mangrove trees (whose dead leaves provide needed nutrients for the bay), is relatively free of pollution, and is deep and big enough to stay cool in the daytime. All of these factors create one of nature’s most beautiful spectacles. Granted, these features must stay in balance for the dinoflagellates to continue to provide their eerie light.
8. Firefly Squid
Lest you think that bioluminescence is just for microorganisms, we will continue to bigger creatures. A good example of this is the firefly squid (Watasenia scintillans) which is found in particular abundance in Toyama Bay off the coast of central Japan. The firefly squid, also known as the sparkling enope squid, has organs called photophores at the end of each tentacle which emit light. This light is used as a siren song for little fish, which the three-inch squid subsequently munches upon. The squid, which generally live 600-1200 feet below the ocean’s surface, is the only cephalopod to develop color vision which may allow them to differentiate between bioluminescent and ambient light. If you’d like to see the firefly squid for yourself, you can take a sightseeing boat from the Japanese port of Namerikawa. Be forewarned, however, the boat leaves at 3AM.
7. Bioluminescent Jellyfish
Beauty is often something to be admired from afar. As beautiful as jellyfish can be, they can provide a terrible sting if people get too close. Nevertheless, a jellyfish that flows and glows is one of the most beautiful sights that nature provides. The species Aequorea victoria (also known as crystal jelly) produces a series of blue light flashes by releasing calcium, which reacts with the photoprotein aequorin. While crystal jelly emits blue and green light, jellyfish throughout the seas emit a rainbow of colors. A newly discovered jellyfish emits a red glow. Jellyfish become luminescent when they are touched (as well as providing that sting) as a warning to their fellow creatures.
The anglerfish may not look like the friendliest denizen of the seas, but the fish uses bioluminescence to its advantage much like the prettier creatures. There are a wide variety of anglerfish and they can be found in both open water and benthic environments. They also take a multitude of forms, including round and long. All of the species are not very big (the largest grow to 250 mm). They do have a big mouth that snaps upon their prey which swims toward the light that sprouts from a long filament which sprouts from the middle of their forehead. Unlike previous creatures, which emit light by being disturbed, the light that spells the end of many tiny swimmers’ lives is produced by a symbiotic relationship with bacteria. One species of anglerfish that you may have heard of, and even consumed, is the goosefish. The tail of the goosefish has been compared to lobster in terms of taste and texture.