Bioluminescence: the ability of animals to generate light. We've seen it from fireflys to deep sea creatures to the flashing green dynoflagellates churned up in the night's crashing waves. It is an internal chemical reaction that provides many animals with unique ways to hunt, communicate, reproduce, or basically just get around in the dark. What is interesting is how much ocean life depends on bioluminescence. And scientists continue to learn more about this marvelous capability.Dr. Edith Widder has been studying bioluminescence for over a decade, first as a grad student up to today as she continues her work as president and senior scientist of ORCA (Ocean Research and Conservation Association). Recently featured in Scientific American, Widder's passion for all things aglow underwater began with her studies in neurobiology and the light-producing plankton, dynoflagellates, that produces the emerald green light seen in the evening surf or wrapped around racing dolphins that leaves long green torpedo trails. (I often enjoy turning my dive light off during a night dive and follow my dive buddies by the light trails they give off from the action of their dive fins.)
Dr. Widder became forever hooked on bioluminescence when she had the opportunity to dive to 800 feet using a WASP - a high-tech cross between a deep sea diving suit, similar to the Newt or JIM suits, and a submersible. Scientific American quoted her reaction, "'I was trying to take some readings with a meter,' Widder says, 'when suddenly the whole inside of the suit lit up blue.' Widder had brushed up against a chain of siphonophores—a colony of jellyfish relatives—sparking their light show. 'It was breathtaking, absolutely breathtaking.'"
She has gone on to design remote camera platforms and other devices to film and observe deep sea bioluminescent organisms in their natural state - unperturbed by large submersibles or dive suits - gaining more insight as to an animal's day-to-day (or should I say, night-to-night) use and purpose for this fascinating function of nature.
According to Widder, there is much more bioluminescence taking place underwater than most people would suspect. If you were to trawl a net from 3000 meters to the surface, over 90% of your catch would be creatures capable of bioluminescence. And Widder has found some pretty unusual examples:
- The cookie cutter shark is able to hide itself from predators or potential prey swimming underneath with a bioluminescent stomach that matches the light coming from above, a technique called counterillumination.
- The scaleless dragonfish can emit and perceive red light - one color that is not typical for bioluminescent animals because of its short wavelength which limits its effectiveness. But this red light capability gives the dragonfish an advantage, allowing it to see potential prey before the prey sees the dragonfish.
- Then there is the deep open-ocean octopus that Widder recently discovered, whose suckers, not needing to cling to a rocky bottom, have evolved into light organs to attract potential prey.
Dr. Widder notes that the study of bioluminescence is not just a look at something fascinating, that there are some very practical applications for ocean conservation, "We are using bioluminescence in a number of different ways to protect the ocean. We are using bioluminescent bacteria to detect toxins in ocean sediments, develop pollution gradient maps and perform water quality monitoring. Since bioluminescence in bacteria is directly linked to the respiratory chain, anything that depresses respiration—like toxins—depresses illumination. That way, we can tell you exactly how unhealthy a sediment is."
Read more about Dr. Edith Widder in Scientific American.
View her April, 2010 presentation at TED.
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