Amphissa columbiana Dall, 1916

Common name(s): Wrinkled amphissa, Wrinkled dove snail, Columbian amphissa

Synonyms:
Phylum Mollusca
Class Gastropoda
Subclass Prosobranchia
Order Neogastropoda
Suborder Rachiglossa
Family Columbellidae (Pyrenidae)
Amphissa columbiana, 3 cm long, trawled from 120 m depth, San Juan Channel, WA
(Photo by: Dave Cowles, July 2005)
Description:  Like other members of Family Columbellidae, this species has a siphonal notch.  It has both axial ribs and spiral ridges on all whorls. Amphissa columbiana has broad axial ribs and finer spiral ridges.  The axial ribs are distinct on the upper (posterior) half of the body whorl but nearly absent from the lower (anterior) half, leaving only spiral ridges at the anterior end.  The aperture is elongated, about 1/2 the length of the shell, is wider or at least not appreciably narrower at the anterior end, and there is a series of folds both on the columella and on the inside of the outer lip of the aperture (photo).  The operculum is not calcified (photo).  The middle third of the outer lip of the aperture is parallel to the long axis of the shell in adults.  The whorls, of which there are usually about 5, are rounded.  The next to last whorl has 20-24 axial ribs.  Length to 3 cm.  May be pink, orange, mauve, yellow, yellowish green, or mottled with brown. The animal is white with darker spots.

How to Distinguish from Similar Species:  Look carefully for the small folds on the columella as well as the outer lip of the aperture in order to key this species to the right family.  Amphissa versicolor grows to only 1.5 cm and the axial ribs are angled instead of aligned with the length of the shell and it may have a pattern of light and dark markings.   Amphissa reticulata, a rare subtidal species, has the middle third of the outer lip of the aperture rounded and also only gets to 1.5 cm long.  In several other members of Family Columbellidae the spiral ridges are found only on the anterior portion of the body whorl.

Geographical Range:  Kodiak Island, Alaska to San Pedro, California.  Common in the Puget Sound area and the outer Northwest coast.  In California A. versicolor is more common.

Depth Range:  Intertidal to 29 m (But the individual above was trawled from a depth of 120 m in San Juan Channel).

Habitat:  Rocky to muddy beaches and subtidally.

Biology/Natural History:  This species is mainly a scavenger on dead flesh and dead algae, which it uses its long siphon to find.  May be found in Enteroctopus dofleini middens consuming the scraps left from discarded octopus meals.  It is a very active snail.  When moving, a single muscular wave moves along the foot from front to back.  They climb well, and often rear up on the back of the foot to feel for new substrate.  A gland on the rear of the foot secretes a thick mucus strand which the animal can use to suspend itself in the water.  Females attach vase-shaped capsules to rocks.  Each capsule contains about 60 white eggs.  The empty shells are often used by hermit crabs.

In a study on San Juan Island, Pernet (2007) found that different individuals of this species matured at very different sizes.  Immature individuals were characterized by shells in which the outer aperture was thin and easily broken.  These individuals were still growing.  Mature individuals had outer apertures which were much thicker, and were growing little or not at all even if they were not as large as some other immature individuals which were still growing.  Pernet concluded that this species has determinate growth.  Exposure in the lab to effluent from Cancer productus did not affect the shell form or thickness, suggesting that the large range of sizes at maturity is not due to a response to predation by the crab.



 

References:

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

General References:
  Harbo, 1997
  Kozloff, 1993
  Morris, 1966
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Sept, 1999

Scientific Articles:
Hartwick, E. B. and G. Thorarinsson, 1978.  Den associates of the giant Pacific octopus, Octopus dofleini (Wulker).  Ophelia 17: 163-166 

Pernet, Bruno, 2007.  Determinate growth and variable size at maturity in the marine gastropod Amphissa columbiana.  American Malacological Bulletin 22: 7-15

Web sites:


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

I do not find these often near Rosario but they are more common in deep trawls here and on the outer coast.



In this photo the shape of the aperture, the siphonal notch, and the uncalcified operculum can be seen.  Trawled from 120 m depth in San Juan Channel.  According to the criteria in Pernet (2007) I would conclude that this individual is sexually mature due to the thick outer lip of the aperture.


In these photos of an individual found washed up on Hobuck Beach, near Neah Bay on the open coast, the folds can be seen both on the columella and on the outer lip of the aperture.  This individual is 3 cm long.


An individual climbs a rock face underwater.
Photo by Kirt Onthank, June 2007



Authors and Editors of Page:
Dave Cowles (2007):  Created original page
Jonathan Cowles (2007):  Updated page with CSS