To about 85mm (3.5in), but has reached 100mm or so.
This large shell should not be confused with any other in our region.
It is distinguished by the three wing-like varices on each
whorl; these vary in size, and can be large and frilly. Between these
varices, the shell has strong chord-like spiral ridges. Very young specimens
look cancellate due to smaller, more numerous longitudinal ribs and stronger,
more numerous spiral ridges. The siphon canal is closed and upturned.
There is one large tooth on the anterior end of the outer lip (thus "hornmouth").
Color: white to brown (dark chocolate or yellowish), usually with spiral
Sitka, Alaska to San Pedro, California, but uncommon south of Point Conception.
This snail lives in the low intertidal and subtidal zones to 65m or more.
In northern areas C. foliatum lives in shallower water than in the
more southern part of its range.
It lives in rocky areas, especially where there are barnacles and bivalves,
it primary food sources.
A very interesting description of this species' sculpture and its transition
from juvenile to adult can be found in the following book:
Morris, R.H., D.P. Abbott and E.C. Haderlie, 1980. Intertidal Invertebrates
of California. Stanford CA: Stanford University Press.
A number of theories have be proposed as reasons for the large varices on
this snail's shell; they may provide protection from predators or may act
as stabilizers to keep the shell aperture-down if the snail is dislodged
and falls through the water.
Like other murexes, the Leafy Hornmouth is a predator. It feeds mainly
on barnacles and bivalves, such as clams and scallops. It does so by
boring through the prey's shell.
Spawning occurs in late February-March, when clusters of yellowish
vase-like egg capsules may be found under rocks. Each case contains 30-80