A high-definition photograph taken by the ROV Hercules on Nashville Seamount (see map below) during a cruise in 2005. In the foreground you can see a live Desmophyllum dianthus coral with tentacles poking out, which is about 10 centimeters across. This solitary coral is living among another deep-water coral species, called Lophelia pertusa, a colonial coral with many polyps (bottom right), as well as many species of purple and orange octocoral (above D. dianthus). The pink arms of a brittle star stretch across the colonial coral toward the Desmophyllum and a spiny sea urchin (far right). (Photo courtesy of DASS05_URI_IFE_IAO_NOAA)
Deep-sea corals form ecosystems on the seafloor, made up of many species of corals and associates. (Photo courtesy of DASS05_URI_IFE_IAO_NOAA)
Individual specimens of the coral Desmophyllum dianthus live for decades to hundreds of years and have visible banding patterns. The vertical growth axis of the coral runs from bottom (oldest) to the top (youngest) in this section cut through a coral specimen, and you can clearly see this banding.
Scientists are not yet sure whether the bands are deposited annually in D. dianthus, but they can still make multiple geochemical analyses along the growth axis to create a high-resolution record of conditions in the ocean in the past. (Photo by Jess Adkins, California Institute of Technology, and Tom Kleindinst, Woods Hole Oceanographic Institution)
The carbonate skeleton of a fossil D. dianthus coral is coated in a brown ferromanganese crust, which has to be removed before scientists can analyze the coral for uranium and thorium to determine its age. This coral is about 40,000 years old. The cut section is where a sample was removed for this analysis. Multiple corals have grown both on a fallen Corallium coral skeleton and on one another. Much of the structure is coated in a black or brown ferromanganese crust. Other corals subsequently settle on this buildup, allowing scientists to investigate the relative timing of deep-sea coral settling. (Photo courtesy of Laura Robinson)
Scientists collected thousands of samples of cold-water corals living on the seafloor during three expeditions between 2003 and 2005 to the New England Seamounts, a chain of extinct underwater volcanoes, starting with Bear, that stretches from the New England coast toward the mid-Atlantic. (Dan Sheirer, U.S. Geological Survey, and Jess Adkins, California Institute of Technology)
A three-dimensional bathymetric map of Muir Seamount (looking from the southwest, with the topography vertically exaggerated by a factor of 10). Scientists collected cold-water coral samples on dives in the notch just to the left of the center part of the map. (Dan Sheirer, U.S. Geological Survey)