Dirona pellucida (Hurst, 1966)

Common name(s): Gold dirona, orange dirona
Synonyms: Dirona aurantia Dirona aurantia
Phylum Mollusca
Class Gastropoda
Subclass Opisthobranchia
Order Nudibranchia
Family Dironidae
Dirona pellucida from Coffin Rocks, about 12 m depth.  This individual is eating a bryozoan, which is the species' diet.
(Photo by: Kirt Onthank summer 2007
Description:   As with other members of suborder Arminacea, the anus is not on the midline of the dorsum but instead is on a conspicuous papilla on the posterior third of the right side of the dorsum.  The rhinophores have no sheath and cannot be completely retracted.  This species is orange to reddish orange with scattered white spots.  Each of the flattened, leaflike cerata has a white line on it which becomes wider as it approaches the tip.  It has an oral (frontal) veil but there is no white line around the front of the frontal veil.  The rhinophores are lamellate and orange to reddish.  Adults are from 3 to 12 cm long.

How to Distinguish from Similar Species:  The cerata on Arminaceans such as this species often make them look a lot like Eolid nudibranchs, but they can be distinguished from Eolids because Arminaceans have the anus on a papilla on the rear third of the body (right side) while Eolids have it on the anterior third of the body (right side). Dirona albolineata has grayish white, salmon, or purple cerata with white lines and a white line around the foot and frontal veil and between the cerata but has no white splotches on the dorsum.

Geographical Range:  King Island, Alaska south to Oregon, plus Siberian coast.

Depth Range:  Shallow subtidal

Habitat:  Rocks, kelp, and mud, sometimes around floating docks.

Biology/Natural History:  This species feeds on bryozoans


 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
 

General References:
  Behrens,1991
  Harbo,1999
  Kozloff,1993

Scientific Articles:

Web sites:

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

This 3 cm-long individual was found on a navigational piling in the Padilla Bay channel leading to the Swinomish Channel entrance. Photo by Dave Cowles, August 2024.
Dirona pellucida


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