Orthopyxis everta

Orthopyxis everta (Clark, 1876) Common name(s):
Synonyms: Eucopella everta
Phylum Cnidaria Class Hydrozoa Subclass Leptotheca (Leptomedusae; Thecata) Order Proboscoida Family Campanulariidae
	Orthopyxis everta, about 2 mm tall, on a tunicate. Note the annulated pedicel and smooth rim to the hydrotheca.
	(Photo by: Dave Cowles, August 2010 )

Description: As with all thecate hydroids, the hydranth of this species is partly enclosed by a hydrotheca. The hydrotheca is bell-shaped and deeper than wide, and able to contain the entire hydranth when it contracts. There is no operculum. The rim of the hydrotheca is smooth and a diaphragm exists in the lower part of the hydrotheca. The hydranths are on slender, annulated individual stalks (pedicels) (see photo above) connected to stolons. The colony produces small medusae (<= 2 mm) that may or may not be released. The medusae have no stomach.

How to Distinguish from Similar Species: Several similar genera such as Campanularia and Clytia have cusps or undulations on the rim of the hydrotheca. Orthopyxis compressa and O. integra have smooth, non-annulated pedicels

Geographical Range: British Columbia to southern California.

Depth Range: 2-77 m.

Habitat: Sometimes found abundantly on kelp

Biology/Natural History: The colonies grow in a stolon. This hydroid retains its gametes. The larvae of the pycnogonid Tanystylum duospinum live parasitically on this species.

References:

Dichotomous Keys:
Carlton, 2007
Kozloff, 1987, 1996 (as Orthopyxis spp)

General References:

Scientific Articles:

Web sites:

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

Another on same tunicate

Another indivudual on the same tunicate. Note the diatoms attached to some stalks.

Authors and Editors of Page:
Dave Cowles (2010): Created original page
CSS coding for page developed by Jonathan Cowles (2007)

Rosario Invertebrates web site provided courtesy of Walla Walla University

Orthopyxis everta (Clark, 1876)

Common name(s):

References: