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Comb jellies hold keys to deep-sea animal adaptations (Image 1)

Deep-sea comb jelly


This deep-sea comb jelly species is one of the largest ctenophores, reaching the size of an American football. This particular one is 20 centimeters long, but its two strong and sticky tentacles stretched for about 10 meters -- 20 times its body length. Their typical depth range is between 700 and 1000 meters, but this one was collected below 3600 meters making it a prime candidate for transcriptome and physiological analysis. [Image 1 of 6 related images. See Image 2.]

More about this image
Through a grant from the National Science Foundation's (NSF) Dimensions of Biodiversity program (grant DEB 15-42679), marine scientists Steven Haddock of the Monterey Bay Aquarium Research Institute, Joseph Ryan of the University of Florida and Erik Thuesen of Evergreen State College are studying how comb jellies exist in the deepest ocean realms.

Also known as ctenophores (pronounced teen'-oh-fours), comb jellies are marine predators found in all oceans, living in both shallow and deep waters. The luminescent drifters are named for the eight rows of shimmering combs that line their translucent bodies. The teeth of these combs are tiny vibrating hairs that propel the creatures through the water. At night, comb jellies glow bright green or flash eerie blue light when disturbed by boaters or swimmers. Like fireflies on land, they produce their otherworldly glow by a chemical reaction involving a light-emitting enzyme.

They are not true jellyfish and they don't have (or need) the stinging tentacles that bell-shaped jellies have. Instead, they use adhesive cells to snare prey, ingesting whatever small creatures they come into contact with as they float along. Vacuum cleaners of the sea, swarms of comb jellies can devour whole patches of freshly spawned fish eggs in a matter of hours.

Haddock, Ryan and Thuesen are using the newest molecular biology techniques to understand ctenophore evolution and diversification, and to investigate the deep sea as a generating force of new adaptations in comb jellies.

The researchers are using scuba expeditions and remotely operated submersibles to collect samples from shallow water and deep-sea habitats to measure ctenophores' physiological capabilities and to sequence their genomes. The results will help scientists understand how animals adapt to life in extreme environments.

To learn more about this research, see the NSF Discovery story Luminescent ocean drifters hold keys to deep-sea animal adaptations. (Date image taken: March or June 2017; date originally posted to NSF Multimedia Gallery: Nov. 28, 2017)

Credit: Steve Haddock

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