is black or purple
above and white below (picture),
a definite raised spire
(but the shell is only about as tall as wide), no siphonal
notch or canal
interior of the shell is pearly. Animal has an operculum
which is thin and horny with spiral lines. Columella
has two small nodes (picture).
is closed by a callus (picture).
to 3 cm diameter. The apex is frequently heavily worn, and
may be encrusted with coralline algae or bryozoans. Animal's
is black on the sides (picture).
on the shell is due to a dark periostracum.
Chlorostoma funebralis (A. Adams,
Common name(s) Black turban snail,
black tegula, black top
|Chlorostoma funebralis in the
intertidal at Cape Flattery.
Diameter approximately 2 cm
|(Photo by: Dave Cowles
How to Distinguish from
Promartynia pulligo has an open umbilicus.
brunnea has only one node on the columella.
Both these species are brown rather than black.
Range: Vancouver Island
to Baja California
Depth Range: Mostly
intertidal of the outer
coast. Rarely found in inland waters such as Puget Sound or
of Juan de Fuca.
History: This species
is an algal grazer, on microscopic films, attached algae, and
It prefers soft algae such as Macrosystis, Nereocystis,
It can be very abundant and conspicuous on the open coast (picture),
especially in the mid-intertidal zone. The slipper shell Crepidula
adunca settles preferentially on this
species. The symbiotic
limpet Collisella asmi (small, black) is often
found on the shell
as well (it grazes on the microalgae on the shell) but this limpet
"switches" Tegula hosts while the filter-feeding
slipper shell stays
put. The species is found more abundantly in open rocky areas
in areas heavily covered with algae. The animal crawls via
(front to back) locomotory waves passing asynchronously down the two
of the foot. They normally crawl about 0.6 to 0.8 mm/second
nearly double this speed if they contact Pisaster
ochraceous. They are said to be
They excrete uric acid which probably helps in water conservation
low tide. Sexes are separate. Males tend to have
of their foot than females have. Larvae grow rapidly but
grow very slowly. Their shell produces prominent growth lines
Large individuals may be 20-30 years old. Eaten by
red rock crab (Cancer
ochraceous, some octopus in southern California,
and some predaceous snails. It flees from Pisaster
but not non-predatory seastars, and may escape predatory snails by
up on top of their shell. If on a sloping surface it simply
and rolls down the slope. One can observe this readily in the
when approaching rocks with this species on them. Many roll
the rocks, but a large portion of these are hermit crabs inhabiting the
shell. These snails were used extensively as food by
Their empty shells are a favorite of hermit crabs.
In an experimental test (Tepler
et al., 2011),
this species chose temperatures far below their physiological optimum
temperature. This response may be due to the adaptive value
seeking refuge in cool, shaded places but likely precludes the species
from functioning the most efficiently.
At least some members of this species have ripe gonads
year in Oregon and California. In California they
spawn multiple times a year but only once in Oregon (late summer or
fall). The most exposed sites are dominated by mature
while juveniles are more common in protected sites. Lifespan
5-8 years in the southern part of the range but up to 30 years farther
north. Egg production also seems to be greater in populations
farther north, and larger individuals are more common there.
and Fairbanks, 1966
et al., 1980
Cooper, Erin Elaine, 2010. Population biology and
reproductive ecology of Chlorostoma
(Tegula) funebralis, an
intertidal gastropod. Ph.D. dissertation, University of
Oregon. 99 pp.
Darby, R. L., 1964. On growth and longevity in Tegula funebralis.
Veliger 6S: pp 5-7
Doering, P. H. and D. W. Phillips 1983. Maintenance of the
shore-level size gradient in the marine snail Tegula funebralis
(A. Adams): Importance of behavioral responses to light and sea star
predators. Journal of Experimental Marine Biology and Ecology 67: pp
Fawcett, M.H., 1984. Local and latitudinal
variation in predation on an herbivorous marine snail.
Frank, P. W., 1975. Latitudinal variation in the
life history features of the black turban snail Tegula funebralis
(Prosobranchia: Trochidae). Marine Biology 31:181-192
del Próo, SA, T. Reynoso-Granados, P. Monsalvo-Spencer, and E.
Serviere- Zaragoza, 2006. Larval and early juvenile development in Tegula funebralis
(Adams, 1855) (Gastropoda: Trochidae) in Baja California Sur, México.
Veliger 48:2 pp 116-120
Moran, A. L., 1997. Spawning and larval development of the
black turban snail Tegula funebralis
(Prosobranchia: Trochidae). Marine Biology 128: pp 107-114
Paine, R. T., 1969. The Pisaster-Tegula interaction:
Prey patches, predator food preference, and intertidal
community structure. Ecology 50: pp 950-961
Paine, R. T., 1971. Energy flow in a natural population of
the herbivorous gastropod Tegula
funebralis. Limnology and Oceanography 16: pp 86-98
Sarah, Katharine Mach, and Mark Denny, 2011.
Preference versus performance: Body temperature of the
intertidal snail Chlorostoma
funebralis. Biological Bulletin 220: pp 107-117
Wright, R.C., 1975. Variations in size structure along a
latitudinal cline, growth rate and respiration in the snail Tegula funebralis.
MS thesis, San Diego State University
General Notes and
Observations: Locations, abundances,
unusual behaviors, etc.:
This view of the underside of C. funebralis shows
the closed umbilicus (brown stain), and the two nodes on the columella
(bumps just above the operculum)
Chlorostoma funebralis are often found aggregated at
as in this photo taken at Shi shi beach, August 2005. Photo
Here is another aggregation in a tidepool, on red algae.
by Dave Cowles, August 2005
Note also the eroded spire, which is common on this species.
Most Chlorostoma funebralis have a bare shell with
spire. Some, however, such as this specimen in a tidepool at
Corona del Mar, CA, may be completely covered
with a short, thick coat of bushy red algae. Note also the
foot of the living snail. Photo by Dave Cowles March 2005
This aggregation is in the intertidal at Point of Arches, south of
Shi Shi Beach.
Chlorostoma funebralis crawls along the sandy bottom
of a tidepool
near Rialto Beach, WA at low tide, leaving a trail behind it.
Authors and Editors of Page:
Dave Cowles (2004): Created original page