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Images: Cell-sized Thermometers

Working in the cold lab aboard the WHOI research vessel Oceanus, biogeochemist Joan Bernhard removes subcores containing deep-sea single-celled organisms from a core of seafloor sediment. (Photo by Joanne Eberhardt, Pratt Institute)

Inside out: WHOI geochemist Dan McCorkle, bundled up for the cold lab in spite of the ship's balmy location off the Bahamas, works with deep-sea sediment samples containing the single-celled bottom-living organisms (foraminifera) he and Joan Bernhard are looking for. (Photo by Joanne Eberhardt, Pratt Institute)

Outside on Oceanus's deck, Dan McCorkle (left) and Joan Berhnard maneuver into place the deep-sea multiple corer. (Photo by Joanne Eberhardt, Pratt Institute)

Joan Bernhard (green hard hat), with University of South Carolina student Katrina Phillips on board R/V Oceanus, carefully carries a sediment core into a refrigerated lab van. (Photo by Joanne Eberhardt, Pratt Institute)

Some benthic foraminifera, such as the one shown in this scanning electron micrograph, are single-celled organisms whose calcium carbonate shells contain information about the temperature of the water they grew in. This may allow them to be used as proxies for past deep ocean temperature. This specimen, Bulimina sp., measures about 400 x 250 micrometers (0.02 x 0.01 inch.) (Photo by Joan Bernhard, Woods Hole Oceanographic Institution)

Small culture chambers called "microcosms" hold deep-sea benthic foraminifera in carefully controlled physical and chemical conditions. When the cells grow and form new shell material, WHOI scientists Berhnard and McCorkle will link shell composition with the precise growth conditions, "calibrating" the shell thermometer. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)