Anisodoris nobilis (MacFarland, 1905)

Common name:  Sea Lemon, Pacific sea lemon, Noble pacific doris
Synonyms: None
Phylum Mollusca
 Class Gastropoda 
  Subclass Opisthobranchia
   Order Nudibranchia 
    Suborder Doridacea 
     Superfamily Eudoridoidea 
      Family Discodorididae 
Anisodoris nobilis:  Beach 4, WA
(Photo by: Robbie Wheeling, July, 2002)
Description:  Body usually 25-75mm, but can reach 260mm.  Bright orange to light yellow or sometimes white.  Nudibranch has dark markings between but not on the tubercles (picture).  Has finger-shaped oral tentacles, and gills numbering six.  This species may produce a lot of sweet, fruity-smelling mucus (photo) when disturbed.  Its gills and rhinophores are usually lighter in color than is the dorsum (picture).  Gills are white-tipped.
How to Distinguish from Similar Species:  Archidoris montereyensis has dark markings both on and between the tubercles, plus does not produce much mucus or a strong smell.  Its gills and rhinophores are usually darker than the dorsum.

Geographical Range:  Kodiak Island, Alaska to Isla Coronados (Baja California). Rare in intertidal in southern part of range

Depth Range:  Low intertidal zone and subtidal to 35m

Habitat:  Common in low intertidal, on rocky shores, harbor pilings

Biology/Natural History:  This is the largest of California nudibranchs.  It has a penetrating, fruity odor, which may be used to fend off predators. It feeds on a variety of sponges, including Axocielita originalis, Astylinifer arndti, Hymenamphiastra cyanocrypta, Lissodendoryx firma, Halichondria panicea, Haliclona permollis, and species in the genera Mycale, Zygherpa, Parasperella, and Prianos.  It may also ingest quantities of organic detritus.  Studies show that individual nudibranchs are conservative in their food habits; they tend to keep eating the same food species, even if they are transferred to other sites.  Spawning period varies with location, but extend for several months.  The mating is reciprocal; partners may be of vastly different size. This species is a simple organism to study the nervous system and thus has been used for much neurophysiological research.

Sponges which live on the motile scallop Chlamys hastata are less vulnerable to predation by this nudibranch.


 
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References:
Dichotomous Keys:

Kozloff (1987)
Smith and Carlton (1975)
 
General References:
Behrens, 1991
O'Clair and O'Clair, 1998
Morris et al., (1980)

Scientific Papers:
Bloom, S., 1975.  The motile escape response of a sessile prey:  a sponge-scallop mutualism.  J. Exp. Mar. Biol. Ecol. 17: 311-321

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


This specimen was photographed at San Simeon, may 1997 by Dave Cowles


Two specimens in a tidepool, San Simeon, 2001, Dave Cowles


A closeup of Anisodoris nobilis dorsum showing the gills, the tubercles, and the dark spots between them.  Photo by Dave Cowles, San Simeon, Ca 2001


Though this species is fairly large, it can still crawl across the underside of the surface film in tidepools.  Photo by Dave Cowles, San Simeon CA May 2001



The rhinophores are completely retractile into sheaths, and are perfoliate.  Photo by Dave Cowles, July 2005



When disturbed the animal often releases sweet-smelling mucus.  The mucus release can be seen here to the top left.  Note also that this individual has very few spots.
Photo by Dave Cowles, July 2006


An underwater photo of two individuals, at least one of which appears to be laying eggs.  Photo by Kirt Onthank, August 2007
 
 
 


Authors and Editors of Page:
Robbie Wheeling (2002):  Created original page
Edited by Hans Helmstetler 1-2003
Edited by Dave Cowles 2005, 2006