Dive 13: “Sleepy Hollow” Dive Site
July 27, 2017
Access Dive Summary and ROV Data

The guyot summit next to the cone on this site was composed primarily of large, broken pieces of manganese-encrusted rock and unconsolidated rubble, most of which appeared to be cemented together and was dusted with sediment. As the remotely operated vehicle (ROV) ascended the flank of the cone, the bottom transitioned to more consolidated manganese-encrusted pillow flows. The community on the way up the flank and in the flats next to the cone showed low diversity and abundance. However, the abundance of animals increased significantly just below the peak, where there was a relatively high density of corals, sponges, other invertebrates, and a few fishes. Colonial octocorals, including coralliids, chrysogorgiids, anthothelids, and bamboo corals were the dominant fauna. Glass sponges were also a significant group; one species was observed with commensal zoanthids. A small number of black corals, mushroom corals, anemones, sea pens, and rock pens were also observed. On the peak, the number of plexaurid sea fans dramatically increased. There were several sightings of a small jellyfish that feeds on bamboo coral polyps. The most common echinoderm was a brilliant red stalked crinoid. Various species of feather stars, ophiuroids, and snake stars were also present. Sea stars included goniasterids, benthopectinids, and a single species of Pythonaster. Sea urchins, some of which were extremely large, were also surveyed. A lobster demonstrated a pronounced escape response to the ROV. Other crustaceans included shrimps, stalked barnacles, and several squat lobsters. At least two species of snails were observed. The fish community at the site included halosaurs, cuttthroat eels, cusk eels, and grenadiers.