HOLLYWOOD Fla. Some deep-sea crabs have eyes sensitive to ultraviolet light, which they may use to snatch glowing plankton and stuff it in their mouths, a new Nova Southeastern University study suggests.
Tamara Frank, Ph.D., a marine biologist and associate professor at Nova Southeastern University's Oceanographic Center, who is the principal investigator of the study, said that crabs living the deep-sea zone --- a pitch dark area at the ocean bottom ---- may be using bioluminescence to help sort out their food.
Duke University marine biologist Snke Johnsen. Ph.D., one of the study's collaborators, explained that the animals might be using their ultraviolet and blue-light sensitivity to sort out the likely toxic corals they're sitting on ---- which glow, producing blue-green and green bioluminescence --- from the plankton they eat, which glow blue.
The sensitivity to shorter ultraviolet wavelengths may give the crabs a form of color vision to guarantee they grab healthy grub, not poison. Frank and her collaborators reported the findings in the Sept. 6 issue of the Journal of Experimental Biology.
Frank has previously shown that certain deep-sea shrimp living in the water column can see ultraviolet wavelengths, even though they live nearly half a mile below the ocean surface, where there's little to no sunlight. Experiments to test deep-sea creatures' sensitivity to light have rarely been done on animals that live on the bottom of the ocean. The new study is one of the first to test how bottom-dwelling animals respond to light.
The team of scientists studied three ocean-bottom sites near The Bahamas. They took video and images of the regions, recording how crustaceans ate and the wavelengths of light, or color, at which neighboring animals glowed by bioluminescence. The scientists also captured and examined the eyes of eight crustaceans found at the sites and several other sites on earlier research cruises
|Contact: Ken Ma|
Nova Southeastern University