Dive 07: “Edmondson” Seamount
July 21, 2017
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Dive 07: Hunting Anglerfish

This deep-sea anglerfish, which measured 20-30 centimeters (7.8 - 11.8 inches) in length, was seen during exploration of "Edmondson" seamount, at a depth of 1,260 meters (~4,135 feet). Anglerfish are ambush predators, lying motionless on the seafloor until unknowing prey swim by to be grabbed and eaten. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana.. Download larger version (mp4, 35.1 MB).

The dive began at a depth of 1,260 meters (~4,135 feet) on rocky, manganese-encrusted basalt bedrock, boulders, and some sediment cover. While sparsely populated, there were several colonies of primnoid octocoral regularly observed with an orange brittle star associate. Other octocorals at the landing site included a few colonies of Hemicorallium precious coral; a tall, “whip” bamboo coral with a large flytrap anemone on its tip; and a colony of Victogorgia nuttingi with an brittle star and pedunculate barnacles. A synallactid sea cucumber was the only echinoderm observed. Further up the dive track we encountered a blocky pinnacle region with a higher-density invertebrate community dominated by often large and tall Hemicorallium, with some colonies partially overgrown by yellow zoanthids. Other cnidarians included Chrysogorgia, a white species of Paragorgia, stoloniferans, corallimorpharians, and zoanthids. The largest colonial cnidarian, however, was a hydrozoan colony that was over two meters (6.6 feet) tall and three meters (9.8 feet) wide that harbored many commensals. Several swimming shrimps and hermit crabs passed by the remotely operated vehicle. Different species of goniasterid sea stars were observed predating on corals – one had its stomach over its prey. Other echinoderms included two white echinothuriid urchins, several large feather stars, numerous brittle stars, and a sea cucumber which may be in the family Laetmogonidae. Sponges included two species of euplectellid glass sponges, several small unidentified spherical sponges, and an undescribed glass sponge tentatively identified as a tretodictyid species with commensal sea anemones or zoanthids growing throughout its branches. Fish included several cusk eels, two species of grenadiers, and a large angler fish.