Aglantha digitale (O.F. Muller, 1776) Common name(s): Pink helmet, pink helmet jellyfish
Synonyms: Aglantha conicus,  Agliscra invertens, Circe camtschatica, Circe impatiens, Circe rosea, Medusa digitale, Trachyneme digitale, Turris borealis
Phylum Cnidaria Class Hydrozoa Order Trachylina Suborder Trachymedusae Family Rhopalonematidae
	Aglantha digitale, about 10 mm long, found by Jamie Anderson Fields at night at Sharpe Cove dock.
	(Photo by: Dave Cowles, August 2025 )

Description:  This common hydromedusa is about 2x as high as it is wide, and has many (80 or more) unbranched tentacles which originate at the margin of the bell. Their eight radial canals are unbranched. They have 8 club-shaped statocysts around the margin of the bell. Rather than connecting directly to the subumbrella, their stomach and manubrium are suspended down on a long peduncle and can extend well below the bell margin. There are four short lips on the end of the manubrium, and the 8 radial canals extend down the peduncle to the stomach. Their 8 gonads are sausage-shaped and hang down from the radial canals up near the apex of the subumbrella,attached only at one end. Thought to exist as medusa only (no polyp). May be colorless, or may have red, pink, or orange on the tentacles. Height 10 to 40 mm. 

How to Distinguish from Similar Species:Crossota sp. is about as wide as it is tall and its stomach attaches directly to the subumbrella. Many other species have multiple gonads but which don't hang down freely from one end like a cluster of sausages, or they don't have their stomach hanging down on a long peduncle.

Geographical Range:  Arctic, North Pacific, and North Atlantic oceans.

Depth Range:  Surface to 200 m

Habitat:  Pelagic

Biology/Natural History:  This species can swim slowly, or activate giant axons to make rapid bursts of speed. This species vertically migrates, living deeper by day and shallower by night. Its diet is mainly copepods. 

References:

General References:
  Wrobel and Mills, 1998

Scientific Articles:
 

Web sites:

General Notes and Observations: Locations, abundances, unusual behaviors:

This closeup photomicrograph of the stomach and manubrium shows the long gelatinous peduncle on the left and the 4 short lips on the end of the manubrium on the right, plus the club-shaped statocysts and the many tentacles, some of which are colored pinkish red, hanging from the bell margin. Photo by Dave Cowles, August 2025

This photograph in natural light shows the pinkish colors of the tentacles in this individual. A crustacean nauplius larva is clinging to it, apparently inside on the subumbrella. This is interesting because this species eats copepods and so likely has toxin effective against crustaceans. Photo by Dave Cowles, August 2025

Authors and Editors of Page:
Dave Cowles (2025):  Created original page
CSS coding for page developed by Jonathan Cowles

Salish Sea Invertebrates web site provided courtesy of Walla Walla University