Arctapodema

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Arctapodema is a genus of deep-sea hydrozoans in the family Rhopalonematidae. They are small jellyfish-like animals with a hemispherical bell up to 23 mm in diameter. Key features include four simple lips, no gastric stalk, eight narrow radial canals with gonads on them near the mouth area, many tentacles arranged in a single row, and edge sensory organs shaped like clubs.

There are four species commonly accepted from the Southern Ocean. One additional name, Arctapodema tetragonia, is not widely accepted as a separate species and may actually be the same as A. ampla because of similar features: a short stomach and four lips, but with four kidney-shaped gonads on the stomach wall near the underside and about 112 tentacles.