top shell with a pearly interior,
no nodes on columella, umbilicus closed, spiral ridges are beaded
and brown on a cream or yellow background. Most anterior
on each whorl is violet or purple. The apex is also usually
(a purple band is also made near the columella). Base of body
is nearly flat. The whorls are only slightly inflated, and
between whorls are not deeply indented. Animal is pinkish
with brown dorsal spots. Shell is up to about 2-3 cm
and usually has 8 flattened whorls. The shell colors fade
Common name(s): Ringed top
snail, Purple-ringed top
|Calliostoma annulatum collected by
Dave Cowles, summer 2002.
Unknown location near Rosario. Approximate
|(Photo by: Dave Cowles)
How to Distinguish from
Similar Species: C.
variegatum also has beaded spiral ridges but they
are all tan or
brown and the animal is cream (not orange) with brown spots. C.
ligatum has unbeaded spiral ridges and the animal
Range: Forester Island, Alaska
to Isla San Geronimo, Baja California
Depth Range: Almost
More common on the open coast than in the Sound/Straits, although it is
abundant subtidally in some areas of the San Juan Islands.
in shallow water.
Lives higher on kelp than does C. ligatum but below
History: This species (along
with C. ligatum and C. canaliculatum) were collected by Captain James
and were among the first mollusk species on the US Pacific Coast to be
named. May climb up kelp stalk toward surface in bright
climb 20-30 feet in a day. Feeds on the kelp itself, or on
diatoms, bryozoans, and hydroids. Will also eat detritus and
even may scavenge dead fish or other sea creatures. May
or nudibranchs. Apparently have "lips" or "jaws" which serve
up prey. Mucus is secreted on the shell, which may help deter
and Carlton, 1975
et al., 1980
and Fairbanks, 1966
General Notes and
Observations: Locations, abundances,
unusual behaviors, etc.:
Underwater photo by Aaron Baldwin.
Authors and Editors of Page:
Dave Cowles (2002): Created original page