Calliostoma annulatum
Common name(s): Ringed top
snail, Purple-ringed top
snail
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Synonyms: |
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Phylum Mollusca
Class Gastropoda
Subclass Prosobranchia
Order
Archaegastropoda
Suborder Trochina
Family Trochidae |
Calliostoma annulatum collected by
Dave Cowles, summer 2002.
Unknown location near Rosario. Approximate
height/width: 2
cm |
(Photo by: Dave Cowles) |
Description: A
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
spiral ridge
on each whorl is violet or purple. The apex is also usually
purple
(a purple band is also made near the columella). Base of body
whorl
is nearly flat. The whorls are only slightly inflated, and
the sutures
between whorls are not deeply indented. Animal is pinkish
orange
with brown dorsal spots. Shell is up to about 2-3 cm
diameter/height,
and usually has 8 flattened whorls. The shell colors fade
after the
animal dies.
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
is orange.
Geographical
Range: Forester Island, Alaska
to Isla San Geronimo, Baja California
Depth Range: Almost
never intertidal.
More common on the open coast than in the Sound/Straits, although it is
abundant subtidally in some areas of the San Juan Islands.
Habitat: Seaweeds
in shallow water.
Lives higher on kelp than does C. ligatum but below
C. canaliculatum
in CA.
Biology/Natural
History: This species (along
with C. ligatum and C. canaliculatum) were collected by Captain James
Cook
and were among the first mollusk species on the US Pacific Coast to be
named. May climb up kelp stalk toward surface in bright
weather--can
climb 20-30 feet in a day. Feeds on the kelp itself, or on
encrusting
diatoms, bryozoans, and hydroids. Will also eat detritus and
copepods,
even may scavenge dead fish or other sea creatures. May
attack anemones
or nudibranchs. Apparently have "lips" or "jaws" which serve
to cut
up prey. Mucus is secreted on the shell, which may help deter
predation.
References:
Dichotomous Keys:
Kozloff,
1987
Smith
and Carlton, 1975
General References:
Morris
et al., 1980
Flora
and Fairbanks, 1966
Kozloff
1993
Scientific Articles:
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
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