Nucella canaliculata (Duclos, 1832) Common name(s): Channeled dogwinkle, Channeled purple
Synonyms:  Thais canaliculata
Phylum Mollusca   Class Gastropoda    Order Neogastropoda     Suborder Rachiglossa      Family Nucellidae
	Nucella canaliculata foraging on Swirl rocks.  Total length about 2.5 cm.
	(Photo by: Dave Cowles July 2011)

How to Distinguish from Similar Species:Nucella ostrina has a thick shell and spiral ridges of 2 different sizes. Nucella lamellosa has only a few large spiral ridges on each whorl and may also have longitudinal ribs or frilly lamellae.  Acanthina spirata has a large tooth on the outer lip of the aperture.

Geographical Range:  Aleutian Islands to Cayucos, San Luis Obispo County, CA; uncommon north of Puget Sound or south of San Francisco Bay.

Depth Range:  Middle intertidal.

Habitat:  Rocky intertidal, often in or near mussel beds.  On protected or exposed coasts.  May be very abundant at some exposed sites on the Olympic Peninsula

Biology/Natural History:  This species does not range as high in the intertidal as does N. ostrina, but higher than does N. lamellosa.  Its main prey is Mytilus spp, and secondarily it feeds on barnacles such as Semibalanus cariosus.  It drills shells by softening them with a secretion from the foot, then drilling through with the radula.  It usually takes 1-2 days to drill and eat a prey individual.  Breeding is in spring and summer.  Females attach their eggs to rocks in flask-shaped capsules ("sea oats"), each of which may contain 15-55 eggs.  Some of the eggs may be abortive and consumed by other larvae as they grow within the capsule.  The young emerge from the capsule as benthic, juvenile snails about 1.3 mm in shell length.

In the study by Sorte and Hofmann (2005), thermotolerance of different Nucella species along the coast was found to be correlated with the latitude range and tidal height each species occupies.  N. ostrina, which occurs higher in the intertidal than does N. canaliculata in Oregon and does not extend as far north, had higher heat tolerance than did N. canaliculata.  N. emarginata, which extends the farthest south, and N. ostrina, which lives higher in the intertidal, recovered more quickly from thermal exposure than did N. canaliculata and N. lamellosa, which live lower in the intertidal, and N. lima, which has a more northern range.  These differences in heat tolerance may be related to HSP70 molecular chaperones.

The famous purple dye from the city of Tyre, that colored royal Roman robes, was made from a relative of Nucella.  The snails were ground up in a stone mortar; different combinations made different shades of purple.  The dye should be fixed with lemon juice as a mordant.  The American species produce a much less brilliant purple than do the Mediterranean species.

References:

General References:
  Harbo, 1997
  Harbo, 1999
  Johnson and Snook, 1955
  Kozloff, 1993
  Morris, 1966
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:
Sorte, Cascade J.B. and Gretchen E. Hofmann, 2005.  Thermotolerance and heat-shock protein expression in northeastern Pacific Nucella species with different biogeographical ranges.  Marine Biology 146: 985-993
 

Wootton, J. Timothy, 2002.  Mechanisms of successional dynamics: consumers and the rise and fall of species dominance.  Ecological Research 17 pp. 249-260

Web sites:
 

In my experience, this species is far less common around Rosario than is Nucella lamellosa (most common) or Nucella emarginata.

A small N. canaliculata.  This individual seems to be covered by small byssal threads.  Photo by Dave Cowles, July 2005