A beautiful primnoid coral with a commensal crinoid (sea lily) and ophiuroid (brittlestar) observed on the dive. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2013 Hohonu Moana. Download larger version (jpg. 1.5 MB).
Today's dive was on Kanehunamoku Seamount north of French Frigate Shoals with the objective of determining the lower depth range of a known dense coral and sponge community found in 2007 during a Pisces submersible dive. The dive started at 2,460 meters on a slope with pillow lava flow formations with some tube formations that were covered with a moderate density of primnoids, isidids, antipatharians (Bathypathes alternata), and sponges. As the ROV moved up the slope, the density of animals remained moderate and was dominated by primnoids, isidids, and black corals, with occasional sponges and crinoids. At 2,240 meters the densities of primnoids, isidids, and sponges became high and remained high through the end of the dive at 2,237 meters. While the ROV did not quite reach the depth of the previous submersible dive conducted in the area (1,700 meters), today's dive observations indicate that a dense coral and sponge community extends down to a depth of approximately 2,250 meters in this area.