Berthella californica (Dall, 1900)

Common name(s): California berthella, White berthella
Synonyms:  Pleurobranchus californica, Pleurobranchus denticulatus
Phylum Mollusca
 Class Gastropoda
  Subclass Opisthobranchia
   Order Notaspidea
    Family Pleurobranchiidae
Berthella californica from Coffin Rocks, WA.  Length about 2.5 cm (Scale in background is mm).
(Photo by: Dave Cowles,July 2005)
Description:  This is one of only two species from Order Notaspidea found in this area.  Although it looks like a nudibranch, it does have a thin, white internal shell (easier to feel than to see) which extends at least 1/2 the length of its body.  It has lateral sheetlike extensions of its body (mantle) like a sheetlike flap above the foot, and a single (prominent) gill on the right side of the body between the mantle margin and the foot (photo).  The rhinophores are rolled and emerge from under the flap in front (photo).  The color is translucent white, cream, or orange with opaque white spots, and often a thin white line around the border of the dorsum.  Length up to 8.5 cm, but usually 2.5 mm or less.

How to Distinguish from Similar Species:  No other nudibranch-like animal in this area is white, with a lateral sheetlike extension above the foot and only one gill on the right side.  Several dorid nudibranchs such as Archidoris odhneri look superficially similar but they have no lateral flap and their gills are a circle on the dorsum.  Tylodina fungina is another Notaspidean, found in southern CA, but it is bright yellow.

Geographical Range:  Point Craven, Alaska to Coronados Island, Baja California

Depth Range:

Habitat:

Biology/Natural History: This uncommon but striking species apparently preys on ascidians and perhaps on sponges.  Little is known about this species.  Some members of this family can repel predators with extremely strong acid secretions from glands in the dorsum.

LaForge and Page studied B. californica development.  The species lays its eggs in a coiled ribbon attached to the substrate along one edge.  The egg ribbon is white, about 1 cm wide, and 1 mm thick.  The egg capsules in the ribbon are oval, around 1.6 or 1.7 mm wide, and contain 1-2 eggs each.  At 11-12 C the eggs hatched as veliger larvae in 19 days.  Its developmental pattern resembles that of nudibranchs more closely than does that of other pleurobranchoideans which have been studied.  They also discovered that the snail-like shell which the larva has only becomes bilaterally symmetrical late in development.  Some of the events that occurred when the larva settled and metamorphosed into the adult form included a rapid expansion of the mantle over the shell so that the shell became internal.  They also lost the large larval velar lobes and began growing the rhinophore and oral veil.  The larva also appeared to have an ospradium (chemosensory organ), though the adult does not.


 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
  Smith and Carlton, 1975
 
 

General References:
  Behrens, 1991
  Morris et al., 1980

Scientific Articles:
LaForge, Nicole L. and Louise R. Page, 2007.  Development of Berthella californica (Gastropoda: Opisthobranchia) with comparative observations on phylogenetically relevant characters among nudipleuran opisthobranchs.  Invertebrate Biology 126(4): 318-334

Web sites:
 


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

We have not often seen this animal around Rosario.



In this view of the right side, one can see the gill (and the gonopore in front of it?)  Photo by Dave Cowles, July 2005



In this view the rolled rhinophores can readily be seen.  Photo by Dave Cowles, July 2005


An underwater photo by Kirt Onthank, July 2007


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