Rostanga pulchra MacFarland, 1905

Common name(s): Red sponge nudibranch, Red sponge doris, Red nudibranch, Crimson doris
Synonyms:
Phylum Mollusca
Class Gastropoda
Subclass Opisthobranchia
Family Rostangidae
Rostanga pulchra, approximately 1 cm long, on a sponge at Swirl Rocks
(Photo by: Dave Cowles July 2005)
Description:   Like all dorid nudibranchs (members of suborder Doridacea), this species has a circle of gills around a mid-dorsal anus.  Rostanga pulchra has no large dorsal outgrowths other than the rhinophores and gills but it does have tubercles scattered all over the dorsum.  The gills can be completely retracted into sheaths.  The color is red to orange-red, sometimes with a few tiny brown or black spots on the dorsum.  The overall shape is oval, though it may taper toward the rear.  The outermost papillae along the margins of the dorsum may have white pigment.  The rhinophores have 10-12 vertically oriented leaves and end in slender papillae.  The rhinophores and gills are the same orange color as the dorsum, although there may be white tips on the gills.  Length to 1.6 cm. (or to 3 cm in California?)

How to Distinguish from Similar Species: Aldisa sanguinea, which lives from Oregon to Baja California and also feeds and lives on red sponges, has perfoliate rhinophores.

Geographical Range: Point Craven, Alaska to the Gulf of California; Chile, Argentina

Depth Range:  Intertidal to 102 m

Habitat:  On and around red sponges

Biology/Natural History:  This species feeds on, and is often found on, red sponges such as Acarnus,Esperiopsis,Ophlitaspongia, and Plocamia.  It lays its eggs in a tight orange circle on the sponges March to October (photo).  The larvae are planktonic for 30-45 days, then settle.  An encounter with at least one prey sponge, Ophlitaspongia pennata, can induce larvae to settle.  It is believed that its orange pigment comes from the sponge.  Adults can locate and navigate to distant Ophlitaspongia sponges by smell.  Some individuals seem to stay quite close to one area while others range for distant sponges.  Predators may include the flatworm Notoplana acticola.  The cephalaspidean predatory nudibranch Navanax inermis is repelled by secretions from Rostanga.


 
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References:

Dichotomous Keys:
  Flora and Fairbanks, 1966
  Kozloff 1987, 1996
  Smith and Carlton, 1975
 

General References:
  Behrens, 1991
  Bruscaa nd Brusca, 1978
  Harbo, 1999
  Hinton, 1987
  Johnson and Snook, 1955
  Kozloff, 1993
  Morris et al., 1980
  Niesen, 1994
  Niesen, 1997
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:

Web sites:

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

Crawling on red algae
This individual is crawling across red algae in a tidepool.  Photo by Dave Cowles, July 2005

Tiny
This 1/2 cm specimen was photographed by Dave Cowles at San Simeon, CA May 2001

Eggs

This species lays red coils of eggs on the red sponge on which it feeds.  Photo by Dave Cowles in a tidepool, July 2012

Pair

This pair of nudibranchs on a sponge near the one shown above with eggs are probably preparing to mate and lay eggs as well.


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