Dinner Plate Jelly (Solmissus sp.)

The Dinner Plate Jelly belongs to the Genus Solmissus, and derives its common name from its flat-shaped bell. Translucent white in color, they often are seen swimming with their long, string-like tentacles pointing upward. They are known for actively hunting their prey, which is generally gelatinous organisms such as ctenophores and other jellyfish. Dinner Plate Jellies are a common sight in the deeper waters above Axial Seamount and Slope Base. They can grow to be 20 cm (8 in) in diameter.
References:
Marine Life Field Guide (Neptune Canada)
http://jellieszone.com/hydromedusae/
http://www.imbc.gr/biblio_serv/deepsea/X4-0007.html
http://emeralddiving.com/id_jellyfish.html
Dinner plate jellies are found in the water column at depths of 700 to 1000 meters. They were seen frequently at Hydrate Ridge in the water column at various depths. Photo Credit: NSF-OOI/UW/CSSF; Dive 1777; V14