Dive 09: “Wetmore” Seamount
July 23, 2017
Access Dive Summary and ROV Data

Remotely operated vehicle Deep Discoverer arrived at 2,150 meters (~7055 feet) depth on manganese-encrusted pillow lava flows, large blocks, and boulders with some patches of sediment and manganese-encrusted nodules. Fauna overall was sparse, with most species found in low abundance. The one exception was a stalked Bolosoma glass sponge. Other glass sponges were documented – including a potentially new yellow species of Poliopogon that was observed in the final minutes of the dive. A carnivorous sponge was seen using its fine spines to capture small crustaceans for food. Colonial cnidarians were observed in low abundance and included “whip” bamboo coral, Chrysogorgiids, Pleurogorgia species, and primnoids. Black corals were present, including a potentially new species. Cnidarians rounded out with a benthic dandelion siphonophore – the first so far on this cruise. Noteworthy echinoderms included the first in situ observation of an unusual “sea star-like” brittle star, a potential new species of sea star, and feather stars. Several fairly translucent deposit-feeding sea cucumbers were seen, permitting observation of sediment in their guts. Arthropod highlights included an ostracod and squat lobster. A solitary stalked tunicate, two cusk eels, and a grenadier were also present.