Okenia rosacea (Macfarland, 1905)

Common name(s): Hopkin's rose nudibranch
Synonyms:  Hopkinsia rosacea
Phylum Mollusca
 Class Gastropoda
  Subclass Opisthobranchia
   Order Nudibranchia
     Suborder Doridacea
      Family Goniodorididae
(Okenia rosacea, San Simeon, CA.  Approx. 1 cm long.
(Photo by: Dave Cowles, May 1999)
Description:  This small, distinctive dorid nudibranch is rose pink.  Although it is a dorid it has long dorsal outgrowths that resemble cerata and almost hide its rhinophores and gill ring.  Up to 3 cm long but usually less than 2 cm.  Body is internally stiffened by calcareous spicules.

How to Distinguish from Similar Species: No other dorid is rose pink and has cerata-like outgrowths of the dorsum. Triopha catalinae and Limacia cockerelli have orange projections but have a white dorsum.

Geographical Range: Coos Bay, OR to Puerto Santo Tomas, Baja California.  Especially common near Monterey Bay

Depth Range: Low intertidal to 6 m

Habitat:_Rocky intertidal, especially in lower midlittoral tidepools, mostly on open coast.

Biology/Natural History: Feeds on the bryozoan Eurystomella bilabiata, which is also a rosy color.  Lays eggs in a narrow rose-colored ribbon spiraled counterclockwise.  The nudibranch Navanax inermis eats this species.  There are no digestive diverticula in the cerata-like growths.  Named after Timothy Hopkins, a railroad executive who helped establish Hopkins Marine Station.


 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
 

General References:
  Behrens, 1991
  Behrens and Hermosillo, 2005
  Harbo, 2011
  Kozloff, 1993
  Morris et al., 1980
  Niesen, 1994

Scientific Articles:


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


A photo taken at Moss Beach, Laguna del Mar, CA by Dave Cowles, April 1993


Authors and Editors of Page:
Dave Cowles (2005):  Created original page