Invasion History

First Non-native North American Tidal Record: 1959
First Non-native West Coast Tidal Record: 1959
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Nassarius fraterculus is native to the Northwest Pacific from the southern shores of Sakhalin and the Kuril Islands, in the Sea of Okhotsk, Russia and along the Pacific Coast of Japan and the Sea of Japan to the shores of the East China Sea (Japan, Korea) (Pilsbry and Stearns 1895; Abbott 1974; Golikov et al. 1976; Huang 2001; Kil et al. 2005; Academy of Natural Sciences of Philadelphia 2013). It has also been collected in the Bonin (Ogasawara) Islands, about 1000 km southeast of Japan, about halfway between Japan and Guam (Academy of Natural Sciences of Philadelphia 2013). This snail has been introduced to Padilla, Samish, and Boundary Bays, in northern Washington and the southern edge of British Columbia, with transplants of Pacific Oysters (Duggan 1960, cited by Carlton 1979; Abbott 1974; Carlton 1979).

North American Invasion History:

Invasion History on the West Coast:

Nassarius fraterculus was first discovered in North America in 1959 in Boundary Bay, British Columbia/Washington (WA) (Carlton 1992). It was subsequently found in 1960 in Padilla Bay, WA and 1963 in Samish Bay, WA (Duggan 1960, cited by Hanna 1966 and Carlton 1979). It is well established in these bays (Gillespie et al. 2007). It was introduced with plantings of Pacific Oysters (Crassostrea gigas) from Japan, but may have been overlooked for years before being reported (Carlton 1979).


Nassarius fraterculus is a small marine snail associated with intertidal and shallow subtidal rocky and gravelly shores. Its shell is solid and dextrally coiled, with a conical spire and 6-7 prominent, rounded whorls. The shell has 16 moderate longitudinal ribs, crossed by faint spiral growth lines. The aperture is oval and about 1/3 of the shell length. The parietal wall is raised and narrow, with a sharp left edge. The umbilicus is a wide chink. The outer lip is thickened and has three interior teeth. The shell is 8-13 mm in length. The color is gray, brown, chestnut, or almost black, with a white or yellowish spiral stripe around the first whorl. Description based on: Pilsbry and Stearns 1895, Abbott 1974, and Golikov et al. 1976.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Prosobranchia
Order:   Neogastropoda
Family:   Nassariidae
Genus:   Nassarius
Species:   fraterculus


Hima fratercula (Dunker, 1860)
Nassa (Hima) fraterculus (Dunker, 1860)
Nassa hypolia (Pilsbry, 1895)
Nassa nodosa (Marrat, 1880)
Nassa semiplicata hiradoensis (Pilsbry, 1904)
Nassa semiplicata hizenensis (Pilsbry, 1904)
Tritia fratercula (Dunker, 1860)

Potentially Misidentified Species



Nassarius fraterculus is a small marine snail associated with intertidal and shallow subtidal rocky and gravelly shores. Little information is available on its biology. Sexes are probably separate, as in Ilyanassa obsoleta (Scheltema 1964) and eggs are laid in capsules attached to algae (Golikov et al. 1964). A YouTube video shows direct development and fully developed juveniles hatching from the egg capsules (2011, Anonymous,

Nassarius fraterculus is reported to occur on rocky and gravelly shores in Russia (Golikov et al. 1976), while in Padilla Bay, Washington it is known mostly from mudflats, eelgrass and oyster habitats (Wonham et al. 2005). It appears to tolerate a wide temperature range, based on its native range. Information on its feeding is contradictory. Golikov et al. (1976) describe it as an 'active predator', while Wonham et al. (2005) suggest that it feeds largely on diatoms. This snail may be an omnivore, similar to I. obsoleta, feeding on benthic diatoms, decaying algae, and carrion (Scheltema 1964).


carrion, invertebrates, diatoms

Trophic Status:




General HabitatUnstructured BottomNone
General HabitatRockyNone
General HabitatOyster ReefNone
General HabitatSalt-brackish marshNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Tidal RangeMid IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Broad Temperature RangeNoneCold temperate-Subtropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Nassarius fraterculus appears to be common, but not dominant, in Padilla, Samish, and Boundary Bays in Washington and British Columbia (Carlton 1979; Carlton 1992; Wonham et al. 2005). Impacts of this snail on other introduced and native biota are not known.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-4a None 0 Native Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1959 Def Estab
P297 _CDA_P297 (Strait of Georgia) 1977 Def Estab
NWP-5 None 0 Native Estab
P293 _CDA_P293 (Strait of Georgia) 1960 Def Estab
NWP-3a None 0 Native Estab
NWP-3b None 0 Native Estab
SP-XII None 0 Native Estab
NWP-4b None 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Abbott, R. Tucker (1974) American Seashells, Van Nostrand Reinhold, New York. Pp. <missing location>

Academy of Natural Sciences of Philadelphia 2002-2024a Malacology Collection Search. <missing URL>

Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Carlton, James T. (1992) Introduced marine and estuarine mollusks of North America: An end-of-the-20th-century perspective., Journal of Shellfish Research 11(2): 489-505

Collado-Vides, L. (2002) Morphological plasticity of Caulerpa prolifera (Caulerpales, Chlorophyta) in relation to growth form in a coral reef lagoon, Botanica Marina 45: 123-129

Gillespie, Graham E.; Phillips, Antan C.; Paltzat, Debbie L.; Therriault, Tom W. 2007 Distribution of nonindigenous intertidal species on the Pacific Coast of Canada. <missing URL>

Golikov, A. N. and 7 other editors. (1976) <missing title>, Nauk, Leningrad. Pp. <missing location>

Hanna, G. Dallas (1966) Introduced mollusks of Western North America, Occasional Papers of the California Academy of Sciences 48: <missing location>

Huang, Zongguo (Ed.), Junda Lin (Translator) (2001) Marine Species and Their Distributions in China's Seas, Krieger, Malabar, FL. Pp. <missing location>

Kil, Hyun Jong; Yoon, Sook Hee; Kim, Won; Choe, Byung Lae; Sohn, Hyun Joon; Park, Joong-Kee (2005) Faunistic investigation for marine mollusks in Jindo Island., Korean Journal of Systematic Zoology Special Issue 5: 29-46

Pilsbry, Henry A. (1901) New Mollusca from Japan, the Loo Choo Islands, Formosa and the Philippines., Proceedings of the Academy of Natural Sciences of Philadelphia 53(1): 193-210

Pilsbry, Henry Augustus; Stearns, Frederick (1895) <missing title>, Stearns, Frederick, Detroit MI. Pp. 196 pp

Riggs, Sharon R. (2011) <missing title>, Padilla Bay NERR, Padilla Bay WA. Pp. 5

Scheltema, Rudolf S. (1964) Feeding habits and growth in the mud-snail Nassarius obsoletus, Chesapeake Science 5(4): 161-166

Wonham, Marjorie J.; O'Connor, Mary; Harley, Christopher D.G. (2005) Positive effects of a dominant invader on introduced and native mudflat species., Marine Ecology Progress Series 289: 109-116