Invasion History

First Non-native North American Tidal Record: 1924
First Non-native West Coast Tidal Record: 1924
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Reishia clavigera is reported to range from northern Japan (Sendai) to Singapore, Borneo, and the Philippines (Abe 1983; Huang 2001; Academy of Natural Sciences of Philadelphia 2014a & b), although some of the tropical records could be a similar species (e.g. R. jubilaea, Singapore). In 1924 and 1951, specimens of R. clavigera were found on newly transplanted Pacific Oysters (Crassostrea gigas) in Washington and British Columbia. There have been no later reports of the whelks in North American waters (Hanna 1966; Carlton 1979).

North American Invasion History:

Invasion History on the West Coast:

In 1924, Kincaid (1947, cited by Hanna 1966; Carlton 1979) collected specimens from newly planted Japanese oysters in Samish Bay, Washington (WA). He found two more of these snails on boxes of oysters about to be planted in Willapa Bay, WA (Kincaid 1947 cited by Hanna 1966; Carlton 1979). In 1951, 63 R. clavigera and their egg cases were removed from a 1948 planting of Japanese Oysters, in Ladysmith, British Columbia (Hanna 1966; Carlton 1979). This whelk is considered to be extirpated in British Columbia, with no further records (Gillespie 2007).


The shell of Reishia clavigera is heavy and dextrally coiled with a short spire, with 5-6 whorls, including a large body whorl. The shell is heavily sculptured with large, blunt knobs, prominent growth lines, and spiral grooves. The body whorl bears five rows of knobs. The interior of the lip of the aperture is scalloped and strongly grooved. The exterior of the shell is grey, brown, or black, with white or gray axial and spiral stripes. The tips of the knobs are usually white. Shells of mature animals range from 20-40 mm long (Abe 1983). This description is based on photographs on websites, e.g. Natural History Museum of Rotterdam ( and (


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Prosobranchia
Order:   Neogastropoda
Family:   Muricidae
Genus:   Reishia
Species:   clavigera


Thais problematica (None, None)
Thais tumulosa (None, None)
Thais clavigera (None, None)
Purpura clavigera (Küster, 1860)

Potentially Misidentified Species

Reishia jubilaea
Tan and Sigurdsson (1990), a similar species distinguished by shell features, radula and penis.

Reishia keluo
Similar species, reported from Taiwan (Wu et al. 2003)

Resihia rufotincta
Similar species, reported from Taiwan (Wu et al. 2003)



Reishia clavigera (Asian Rock Shell) is a predatory snail of the intertidal and shallow subtidal rocky shores and oyster beds. Sexes are separate, and fertilization is internal. Adult snails (20-45 mm) form large breeding aggregations. Females lay masses of egg capsules on pebbles and boulders (Abe 1983). The eggs hatch into planktonic veligers, which settle.

In Taiwan, R. clavigera prefers intertidal areas, and has a higher temperature preference (36C) than two other intertidal Reishia species. This whelk is a predator,feeding on barnacles, chitons, gastropods, bivalves, and polychaetes (Wu et al. 2006).


barnacles, chitons, gastropods, bivalves, worms


Cronia margariticola (predatory snail)

Trophic Status:




General HabitatOyster ReefNone
General HabitatRockyNone
General HabitatMarinas & DocksNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Maximum Temperature (ºC)36Preferred temperature, experimental (Wu et al. 2006).
Minimum Length (mm)20Abe 1983
Maximum Length (mm)45Abe 1983
Broad Temperature RangeNoneCold temperate-Tropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Reishia clavigera was found on newly planted Japanese oysters (Crassostrea gigas) in Samish Bay, Washington and Ladysmith, British Columbia, but did not become established. No impacts have been reported (Carlton 1979; Gillespie 2007).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-3b None 0 Native Estab
NWP-3a None 0 Native Estab
NWP-2 None 0 Native Estab
EAS-I None 0 Native Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1924 Def Extinct
P293 _CDA_P293 (Strait of Georgia) 1924 Def Failed
NWP-4b None 0 Native Estab
EAS-III None 0 Native Estab
EAS-VI None 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Abe, Naoya (1983) Proceeding of the second international conference on the malacofauna of Hong Kong and southern China, Hong Kong University Press, Hong Kong. Pp. 381-392

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

Academy of Natural Sciences of Philadelphia 2006-2014b OBIS Indo-Pacific Molluscan Database. <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

Claremont, Martine; Vermeij, Geerat J.; Williams, Suzanne T.; Reid, David G. (2013) Global phylogeny and new classification of the Rapaninae (Gastropoda: Muricidae), dominant molluscan predators on tropical rocky seashores, Molecular Phylogenetics and Evolution 66: 91-102

Gillespie, Graham E. (2007) Distribution of non-indigenous intertidal species on the Pacific Coast of Canada, Nippon Suisan Gakkaishi 73(6): 1133-1137

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

Harvard Museum of Comparative Zoology 2008-2021 Museum of Comparative Zoology Collections database- Malacology Collection. <missing URL>

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

Tan, K. S.; Sigurdsson, J. B. (1990) A new species of Thais (Gastropoda: Muricidae) from Singapore and peninsular Malaysia, Raffles Bulletin of Zoology 38(2): 205-211

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database.

Wu, Jing-Ying; Liu, Yu-Chih; Meng, Pei-Jie; Chiu, Yuh-Wen; Liu, Li-Lian (2006) Local distribution and temperature preferences of predatory whelks (Thais spp.) in Taiwan: Implications for oyster culture, Journal of Shellfish Research 25(2): 379-384