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.
Kozloff 1987, 1996
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
After a few days in the tank the above individual began laying
Although I inadvertently disturbed the individual and removed it from
eggs at least twice, over the course of a week it returned again and
to the same egg mass and continued laying eggs. The eggs are
to the substrate in a spiral pattern of capsules (see photos
Each capsule has several hundred eggs (see photo below).
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.
Authors and Editors of Page:
Dave Cowles (2005): Created original page