Hormiphora cucumis (Mertens, 1833) Common name(s): Comb jelly
Synonyms: Janira cucumis, Euplokamis cucumis, Beroe cucumis
Phylum Ctenophora Class Tentacula  Subclass Typhlocoela  Order Cydippida  Family Pleurobrachiidae
	Hormiphora cucumis, about 8 cm long, found in tidepool near Cape Flattery.  The mouth is to the left and one tentacle can be seen.
	(Photo by:  Dave Cowles, July 2012)

Description:  Like all members of Order Cydippidae, this comb jelly is solid, rounded at both ends, has no major projecting lobes, and has two tentacles which arise from sheaths on opposite sides of the body.  In this species the mouth is relatively large but not as large as in a Beroe.  The tentacle sacs are aligned with the pharynx for most of their length.  The tentacles arise in the midsection closer to the aboral end of the body (about 1/3 of the length from the aboral pole).  The tentacles have side branches (tentillae) as does Pleurobrachia, but the tentillae are sparse and in an ordered, comblike pattern rather than disorganized.  The comb rows run nearly the full length of the body and are all equal in length.  The body is elongate and nearly circular to slightly flattened in cross section.  Transparent or slightly blue.  Length to at least 10 cm.

My thanks to Claudia Mills for help with tentative identification of this species.

How to Distinguish from Similar Species:Pleurobrachia bachei also has a pair of branched tentacles but it is much smaller, more nearly circular or just slightly oblong in shape, and is often found near shore. Beroe spp have no tentacles and have a larger mouth. Bolinopsis infundibulum has lobes.  Note:  Mertens (1833) apparently originally described this species as Beroe cucumis but it has been moved to H. cucumis because of its tentacles.  Some of the literature references to B. cucumis may actually refer to this species.

Geographical Range:  Pacific Ocean, Gulf of Alaska and Japan, Prince William Sound, open ocean of WA-British Columbia coast.

Depth Range:  Probably epipelagic

Habitat:  Probably mostly oceanic

Biology/Natural History:  This species is a strong swimmer and is found mostly offshore, but may occasionally be trapped in tidepools when it ventures near the coast.
 

References:

General References:
   Wrobel and Mills, 1998

Scientific Articles:
Welch, V.L. and J.-P Vigneron, 2007.  Beyond butterflies-the diversity of biological photonic crystals.  Optical and Quantum Electronics 39:4-6 pp. 295-303.  DOI: 10.1007/s11082-007-9094-4

Web sites:
Mills, C.E. Internet 1998-present. Phylum Ctenophora: list of all valid species names. Electronic internet document available at http://faculty.washington.edu/cemills/Ctenolist.html. Published by the author, web page established March 1998, last updated 2012

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

I have rarely (only once so far) encountered this ctenophore.

Click here for a movie of the ctene rows beating.

Salish Sea Invertebrates web site provided courtesy of Walla Walla University