Fusitron oregonensis (Redfield, 1848)
Common name(s): Hairy triton, Oregon hairy triton
|Synonyms: Argobuccinium oregonense|
|Fusitron oregonensis from 15 m depth, Sares Head. Total length
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)|
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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Gotshall and Laurent, 1979
McConnaughey and McConnaughey, 1986
O'Clair and O'Clair, 1998
Ricketts et al., 1985
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.|
This egg cluster was brought up from 110 to 180 m depth in the San Juan Channel, 2010. It is attached to a side plate of a barnacle. Cluster width 3 cm.