Bioluminescence, by definition, is the emission of visible light by living organisms. Of all the discovered bioluminescent groups out there, 80% are found in the depths of the world’s oceans. In fact, most deep sea creatures glow in some fashion. On land, however, bioluminescent creatures are less widely distributed. There are no known flowering plants, birds, reptiles, amphibians, or mammals that emit light. Of course, the best place to see these creatures glow is in the dark. You also have to allow your eyes to adjust and observe this amazing phenomenon in all its glory. Remember running around your backyard at night catching fireflies (lightning bugs) as kids? What other amazing creatures glow in the dark? You’d be surprised.
10. The Land Snail, Quantula Striata
While there are plenty of glowing aquatic molluscs, there is only one snail on land known to produce light: the tropical species, Quantula striata. In fact, it is the only land gastropod (among thousands of snails and slugs) known to be bioluminescent. It is so elusive (as many snails are) that a picture in the dark could not be procured. The eggs have been observed as having globules that glow in the dark continuously. Juvenile and adult snails can produce short bursts of green light. While many land snails communicate through pheromones, it is suggested this tropical species may also use its bioluminescence as a form of communication.
9. Antarctic Krill
Antarctic krill are among the most important animals in the Antarctic food chain, ranking right under the phytoplankton on which they feed. When krill congregate in an area (called a swarm) during the warmer months, animals from all parts of this bitter cold region get ready for a feast. This is because krill affects life from every angle in Antarctica. Krill densities can reach as high as 30,000 individuals per m3! That’s a lot of krill and food for predators! With krill comes hungry fish that are gobbled by species such as seals, penguins, and birds. Krill have numerous organs which can glow a yellow-green light for up to 3 seconds at a time. It is not known exactly why krill glow, but it is thought by some scientists that krill illuminate to avoid predators from the deep by blending into the brightness of the sky and ice above the surface. As important as krill are in the food chain, it would make sense they developed such a tactic to blend in and try to avoid the inevitable.
8. Millipedes in the Genus Motyxia
The only millipedes that glow in the dark are all the species in the genus Motyxia (in which there are eight total). They are known as Sierra luminous millipedes and have been recently discovered to emit a greenish-blue light, especially when disturbed. Some species have only a faint glow while others glow incredibly bright. There are very few photos of these millipedes getting their glow on, but the one pictured above (Motyxia sequoiae) was demonstrated through recent partnered research at Tulane University and the University of Arizona. These millipedes are only found in California forests. Another cool little tidbit is that they can’t even enjoy their own light shows: because they’re blind! While these millipedes rely on other senses to hunt for rotting debris, their predators are usually mammalian hunters such as rats. Like other poisonous creatures, the cyanide-containing millipedes had to find a way to display their toxic status to predators through visual cues. Since Motyxia millipedes are nocturnal, having bright colors like some venomous snakes isn’t very helpful in the dark, so these little creatures have evolved bioluminescence to send a clear message.
7. Crystal Jelly (Aequorea Victoria)
Crystal jellies are nearly transparent, floating with the ocean currents. While they look delicate, these graceful creatures are carnivorous. They consume other jellyfish as well as zoo plankton and small crustaceans. They are able to emit a green-blue glow with over 100 tiny, light-producing organs surrounding their outer umbrella. Crystal jellies are collected for their luminescent photo-proteins which are used as bio-markers in research studying genes and detecting calcium.
6. Dinoflagellates – Blue Ocean Glows
Dinoflagellates consist over 2,000 protists species including the toxic red tide. While they can be found in both fresh and salt water, the majority of dinoflagellates live in marine environments making up a large portion of phytoplankton. Certain species can produce a brilliant bioluminescence. When these microorganisms are disturbed, either naturally or by man-made waves (boats, swimmers, fishermen wading, etc.), the water’s surface lights up in a beautiful blue ocean glow. Noctiluca scintillans, known as “sea sparkle”, is a free-floating marine species of dinoflagellate, most likely the species displayed in this photo. The glow acts as a defense mechanism that may warn off predators or attract hunters even higher up on the trophic scale. The end result of this effect is that these little critters ingeniously help make prey out of the predators that would otherwise be stalking them.