Best laid plans
October 2, 2012
One thing about working at sea is that you have to learn to go with the flow. Today started out with a normal remotely operated vehicle (ROV) launch at 6:30 a.m., but less than an hour into the dive the ship’s crew noticed a problem with the ROV tether. Unfortunately, it turned out to be a showstopper, and we had to recover the vehicle so the ROV pilots could work on the problem.
Without ROV operations to count on for animal collections, our blue-water dive team, consisting of Steve Haddock, Meghan Powers, Freya Goetz, and Olivia Judson, sprang into action. The National Geographic photographers, David Liittschwager and Zach Kobrinsky, used the opportunity to catch up photographing some specimens from last night’s trawl and clean their camera gear. The rest of us took some time to inventory the lab and catch up on other projects.
Over the past few days we’ve highlighted many animals that are bioluminescent, but the Haddock lab is investigating both bioluminescence and fluorescence in marine organisms. Bioluminescent animals are able to create light using internal chemical processes, i.e., they produce their own glow, like a firefly. There is a wide variety of ways that animals use bioluminescence for both defensive and offensive purposes.
Fluorescent animals can absorb light from a source (for example, blue light in the ocean) and reemit the light at a longer wavelength (more green or red). But, when the light source is taken away they do not glow. Steve has attached a blue LED array to the ROV so we can shine blue light only and search for new fluorescent animals in the field. Recent research by Steve and Philip Pugh gives an elegant example of how fluorescence may be used to attract prey by the siphonophore, Resomia ornicephala. We know from lab dissections that this animal eats krill. When we encounter it in situ, its long tentacles are slowly jigging up and down, and its lures are fluorescent. This animal has been nicknamed “R-200,” because it is found in a very narrow depth range around 200 meters (650 feet). Steve suggests that “R-200” lives at this depth because the lures are adapted for a particular light level coming from the surface and fluoresce in such a way that they mimic a yummy dinner item for a krill. When the predator (the krill) comes in to feed, it becomes entangled in stinging siphonophore tentacles, and instead becomes prey.
Fingers crossed for a successful ROV launch tomorrow morning! In the meantime, here’s more information on bioluminescence vs. fluorescence, and some amazing images of animals that emit light.