Octocorals dominated the benthos at East “Wetmore” Seamount and included the stunning Iridogorgia and bamboo coral in the foreground. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana. Download larger version (jpg, 2.2 MB).
This Hexactinellid glass sponge was found at approximately 2,065 meters (~6,775 feet) with an associated undescribed species of Antipathes black coral. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana. Download larger version (jpg, 1.4 MB).
The sweeping spirals of Iridigorgia corals are not just beautiful to look at, they are also masterful design, allowing the coral to filter water for food from all directions. This coral was seen during Dive 10, while exploring the east portion of "Wetmore" Seamount. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana.. Download larger version (mp4, 30.5 MB).
The substrate was composed of large manganese-encrusted boulders and blocks that later gave way to cemented lava boulders and basalt; there was a light sediment overlay. Initially, a strong current came from the southeast; later, it came from the north. While the quantity of animals fluctuated in places along the crest of the ridge, the community could be described as high-density. Octocorals were the dominant fauna and included isidids, primnoids, chrysogorgiids, coralliids, Paragorgia, several species of mushroom corals, and a few sea pens. Several species of black corals observed included an undescribed species living in association with a glass sponge, zoanthids, and small anemones. Hexactinellid glass sponges were abundant, particularly Poliopogon, Caulophacus, Bolosoma, and Aspidoscopulia species. There were many associate echinoderms, such as brittle stars and crinoids. Few sea cucumbers were present, possibly due to the lack of sediment. Also observed were large purple echinothuriid urchins, an unusually small cidaroid urchin, and sea stars that included the coral predator Hippasteria. Other taxa surveyed included large patches of dead barnacles, a stone crab, squat lobsters, swimming shrimp, and small lyrate-shaped invertebrates that may have been cladorhizid demosponges. Relatively few fish were seen – only a cutthroat eel and two grenadiers. At the end of the dive, a finned octopod was briefly caught on video.