Orthopyxis sp. (integra?) Common name(s):
Synonyms:  possibly Eucopella caliculata, Agastra mira
Phylum Cnidaria  Class Hydrozoa Subclass Leptotheca (Leptomedusae; Thecata)  Order Proboscoida  Family Campanulariidae
	Orthopyxis sp. medusa captured at early night from Sharpe Cove dock by Jamie Anderson Fields.
	(Photo by:  Dave Cowles, June 2025)

Description:  The small, short-lived medusa of this species has no tentacles and no manubrium. It has four radial canals with attached gonads. This individual appears to be a female with still some eggs inside. Maximum length 2 mm.

Note: Description of this hydromedusa species both in Kozloff (1987, 1996) and Carlton (2007) do not describe it any closer than genus. However, the diagrams in Carlton (2007) of Orthopyxis integra match its appearance best so that is my tentative identification of this species.

How to Distinguish from Similar Species: The medusa of Zanclella bryozoophila also has no tentacles but it has a manubrium with attached gonads.

Geographical Range:  Cosmopolitan; Alaska to San Diego in the NE Pacific.

Depth Range:  Low tide to 439 m for O. integra

Habitat:  Pelagic

Biology/Natural History:  Some of Orthopyxis spp. biology based on descriptions of several species: Some Orthopyxis hydroids have an alternation of generations with both polyp and medusa. However, the lifespan of the medusa is very short and ephemeral-only an hour or less for O. compressa. The medusae of that species are shed from the polyp at dusk, with female medusae released 15-20 minutes before the males. Soon after their release they shed their gametes and die. The individual above appears to still be retaining many eggs so it was likely shed from the hydroid quite recently. Other Orthopyxis species such as O. everta often retain their gametes in the hydroid, so this medusa is likely not that species.

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General References:
 

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Web sites:

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

Authors and Editors of Page:
Dave Cowles (2024):  Created original page
CSS coding for page developed by Jonathan Cowles

Salish Sea Invertebrates web site provided courtesy of Walla Walla University