Fusitron oregonensis (Redfield, 1848)

Common name(s): Hairy triton, Oregon hairy triton
Synonyms:  Argobuccinium oregonense
Phylum Mollusca
 Class Gastropoda
  Subclass Prosobranchia
   Order Mesogastropoda
    Suborder Taenioglossa
     Family Cymatiidae
Fusitron oregonensis from 15 m depth, Sares Head.  Total length 13 cm.
Besides the hairy periostracum, there is a tubeworm and several tunicates growing on this individual.
Note the siphon protruding from the siphonal canal at the left.
(Photo by: Dave Cowles June 2005)
Description:  This large snail has a raised spire, about 6 distinct, rounded whorls with spiral ridges and axial ribs and separated by well-developed sutures.  It has a well-developed siphonal canal which is about 1/3 the length of the aperture and is open all the way (picture).  The brown, horny operculum is slightly smaller than the aperture (picture).  It has a distinctive heavy covering of brown periostracum which forms large hairs or bristles.  The aperture is about 2/5 the total length of the shell.  This is the largest shelled gastropod in our area besides the abalones.

How to Distinguish from Similar Species: Ceratostoma foliatum, the leafy hornmouth, is approximately the same size and shape but has no brown bristly periostracum.  Snails such as Trichotropis cancellata from family Capulidae do have bristly periostracum but rarely exceed 4 cm, have a more round aperture, and do not have a siphonal canal.

Geographical Range: Aleutian (Pribilof) Islands to San Diego, CA; also in Japan

Depth Range: Very low intertidal to 2000 m.  More abundant subtidally than intertidally.

Habitat: Rocky bottoms (not found as often on soft bottoms).

Biology/Natural History: Feeds on ascidians (such as the one growing on the shell!), urchins, bivalves, sea stars, brittle stars, chitons, abalones, and polychaetes.  Urchins which have been attacked by this species have a blackish, tarlike discolored scar.  It produces sulfuric acid in its salivary glands, which may help in boring through shells.  A gland in the proboscis secretes an anesthetic used for subduing prey.  It feeds with biting jaws as well as a radula.  This snail has separate sexes, which move to shallower water to spawn.  The egg masses are large spirals of attached grains that look like bluish, translucent corn.  The females lay their eggs in communal masses (called "sea corn") from up to 30 females.  It takes each female about 2 weeks to lay her entire clutch of eggs.  Veligers hatch from the eggs in about 8 weeks.  Humans should not eat this snail because it carries a pathogen in its salivary glands which can be fatal to humans.  The empty shells are often inhabited by the largest species of subtidal hermit crabs.


 
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References:

Dichotomous Keys:
Kozloff 1987, 1996
 

General References:
Gotshall, 1994
Gotshall and Laurent, 1979
Harbo, 1997
Harbo, 1999
Kozloff, 1993
McConnaughey and McConnaughey, 1986
Morris, 1966
Niesen, 1997
O'Clair and O'Clair, 1998
Ricketts et al., 1985
Sept, 1999

Scientific Articles:
 


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


Note the wide aperture, long but open siphonal canal, and horny operculum which is smaller than the widest dimension of the aperture. A barnacle is growing near the apex of the spire.
Photo by Dave Cowles, June 2005


This individual has slightly less hairy periostracum.  Photo by Dave Cowles at Friday Harbor Labs, July 2006


The animal's body is a pinkish tan mottled with brown.  Note the siphon extending from the siphonal canal.
This animal is clinging to the side of a tank so its shell is farther off the body than would normally be seen.

After a few days in the tank the above individual began laying eggs.  Although I inadvertently disturbed the individual and removed it from its eggs at least twice, over the course of a week it returned again and again to the same egg mass and continued laying eggs.  The eggs are cemented to the substrate in a spiral pattern of capsules (see photos below).  Each capsule has several hundred eggs (see photo below).
 
 
Here the snail is hard at work for the third time, adding egg capsules around the outer edge of the cluster of egg capsuless which had been laid earlier. The eggs are laid in a cluster of capsules.  Each capsule is rectangular and flattened, with one of the narrow ends glued to the substrate. The capsules are about 1.5 cm long, 1 cm wide, and 2 mm thick, composed of a tough, clear gelatinous material.  Each contains several hundred eggs.  This capsule had been attached to the substrate via the expanded capsule casing on the right.  Note that the capsule is slightly wider at the top (left in the photo above) than elsewhere.


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