World Ocean Census - Extract 17 - Life in a cold seep environment

23 May 2010

Several animals have developed highly specialized relationships with cold-seep bacteria. One of these, a clam, obtains its food from the bacteria. How does this happen?

The clams and the bacteria live together and help each other in an exchange process called symbiosis. In the cold-seep community, bacteria make their home inside the clam’s gills. Clams have a muscular foot that helps them attach to the seafloor, and this foot takes in hydrogen sulfide from the water of the cold-seep area. The hydrogen sulfide, produced by methane-using microbes found in the seep, is carried by the clam’s blood to its gills, where the bacteria live. The bacteria use chemical energy found in the hydrogen sulfide to combine carbon dioxide and water, creating sugars and other compounds needed for growth. The bacteria and the sugars released then become food for the clam.

Likely because of the cooler temperatures and the stability of their environment, many cold-seep organisms are much longer-lived than those inhabiting hydrothermal vents. Recent research has revealed that the seep tube worm (Lamellibrachia luymesi) may be the longest-living noncolonial invertebrate known, with a lifespan between 170 and 250 years.

Cold seeps develop a unique topography over time. They can become littered with carbonate rocks ranging from small pebbles to huge blocks, which are thought to be formed by byproducts of microbial metabolism precipitated from seep waters.






This species of hermit carb from a cold-deep site off New Zealand is as yet unnamed. Note the furry-looking seep-associated bacterial filaments on its claws. Courtesy of NOAA/NIWA.







Brine seeps create a ghostly effect in the Gulf of Mexico. Courtesy of NURC/ UNCW and NOAA/FGBNMS

Text and images reprinted with permission from World Ocean Census: A Global Survey of Marine Life by Darlene Trew Crist, Gail Scowcroft and James M. Harding Jr., Firefly Books, 2009

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