Tochuina tetraquetra (Pallas, 1788)

Common name(s): Tochni, Orange peel nudibranch

Synonyms: Tritonia gigantea, Tritonia aurantia
Phylum Mollusca
Class Gastropoda
Subclass Opisthobranchia
Order Nudibranchia
Suborder Dendronotacea
Family Tritoniidae
Tochuina tetraquetra, about 12 cm long.  
(Photo by: James Nestler subtidally off Northwest Island, July 2006)
Description:   Members of  suborder Dendronotacea do not have an anus on the dorsal midline.  They have dorsal outgrowths besides the rhinophores, consisting of branched cerata or gills.  The rhinophores are solid (not rolled), pulpit shaped, and retractable into a cuplike sheath.  Tochuina tetraquetra has a large, stout body with white, plumose gill tufts along the undulating dorsolateral margin all the way from the rhinophores to the posterior tip.  The anterior border of the oral veil is white and crenulate but does not have papillae.  The dorsum is orange or yellowish-orange with white-tipped tubercles.  The foot is salmon pink to yellow with a white margin.  The rhinophores have 6-10 short, vertical plumose proceesses encircling the main shaft below the tip.  Length to 30 cm and weight to 1.4 kg.

How to Distinguish from Similar Species:   The combination of orange color and white plumose gills around the margin is unique.  Of the other orange opisthobranchs in our area,Berthellina engeli is smooth and has rolled rhinophores, Acanthodoris lutea has a circle of gills around the dorsal anus and has many papillae and yellow specks, Triopha maculata has a circle of gills around the dorsal anus and several orange dorsal processes, Aldisia sanguinea and Rostanga pulchra have a circle of gills around the dorsal anus and is 2 cm or less long, Anisodoris nobilis has a circle of gills around the dorsal anus and has black spots, and Dendrodoris fulva and Doriopsilla albopunctata have tubercles with white tips but have a circle of gills around the dorsal anus.

Geographical Range:  Kuril Islands, USSR; Alaska to Malibu, CA

Depth Range:  Subtidal to 363 m

Habitat:  On rocks

Biology/Natural History:  This uncommon species feeds on hydroids, sea pens such as Ptilosarcus gurneyi, and other Alcyonaceans such as the soft coral Gersemia rubiformis (photo).  In the Kuril Islands (Russia) this species is eaten raw or cooked as "Tochni".  This species is said to be the world's largest nudibranch.


 
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References:

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

General References:
  Behrens, 1991
  Harbo, 1999
  McDonald and Nybakken, 1980
  Morris et al., 1980

Scientific Articles:

Web sites:

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


With Gersemia

This larger view of the same individual as above shows pink patches of sea strawberry, Gersemia rubriformis, one of this species' preferred foods, around the nudibranch.
The pink lumps beside the nudibranch may be Gersemia that the animal has already grazed on.
The anemones present are Cribrinopsis fernaldi (pink striped tentacles, beside the nudibranch) and Metridium giganteum (white, bottom of picture)
Photo by Jim Nestler, July 2005


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