Invasion History

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

General Invasion History:

Neptunea arthritica is a large marine snail, native to the shallow sublittoral zone of the Northwest Pacific. It ranges from the Pacific maritime region of Russia, south to central Japan and the Yellow and Bohai Seas (Huang 2001; Fujinaga 2003). Only two specimens are known from outside of this species native range, one in Samish Bay, Washington in 1953 (Hanna 1966; Carlton 1979) and another from the Black Sea (Shadrin 2002).

North American Invasion History:

Invasion History on the West Coast:

A single specimen of the large whelk Neptunea arthritica was collected in Samish Bay, Washington, north of Puget Sound (Hanna 1966; Carlton 1979). It is not known whether the snail was alive when collected. Oyster plantings are a likely vector for this introduction.

Invasion History Elsewhere in the World:

A single living specimen of Neptunea arthritica was collected in 2002 near Sevastopol, Ukraine in the Black Sea. The snail was small and only about a year old (Shadrrin 2002; Son 2010).


Neptunea arthritica is a large, predatory snail, with a moderately prominent spire. Adult shells are dextrally coiled and have 5-6 whorls, with the body whorl making up much of the shell. The aperture is oval and roughly half the shell length. The siphonal canal is moderate in length and somewhat twisted. The channel has a square bottom and the shoulder above the suture bears large rounded knobs. The shell has prominent growth lines and may have spiral bands of darker brown or white. The shell is brown; with brownish-purple longitudinal stripes. The shell may reach or exceed 100 mm in size. Description based on: Abbott 1974, Lee 2006 (photo), Miranda et al. 2008, and (Note- the specimen on the right is left-handed!).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Prosobranchia
Order:   Neogastropoda
Family:   Buccinidae
Genus:   Neptunea
Species:   arthritica


Potentially Misidentified Species



Neptunea arthritica is a large predatory marine snail. Sexes are separate and mature at around 4.5 years and 60 mm in size for males, and 6 years and 75 mm for females (Fujinaga 2003). Eggs are laid in masses of 15 - 65 eggs, deposited on rocks, shells, ropes, and kelp holdfasts. Eggs took 3-4 months to develop and hatch into miniature snails, ~10 mm long (Fujinaga 2003).

Neptunea arthritica inhabits rocky subtidal areas in cold-temperate marine waters (Fujinaga 2003). However, one specimen apparently survived for some time in the Black Sea (Shadrin et al. 2002). This snail feeds on live and dead mussels, scallops, and other bivalves, and on dead crabs and sea-urchins (Fujinaga 2003).




Fish, crabs, humans

Trophic Status:




General HabitatOyster ReefNone
General HabitatRockyNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Length (mm)60Minimum size at maturity, males; 75 mm for females (Fugjnaga 2003).
Maximum Length (mm)110Miranda et al. 2008
Broad Temperature RangeNoneCold temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Neptunea arthritica is an important fisheries organism in Japanese waters, although stocks have greatly declined due to imposex, cause by pollution (Fujinaga 2003; Miranda et al. 2008). This whelk has not become established, and has no impacts, outside its native range.

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 1953 Def Failed
P293 _CDA_P293 (Strait of Georgia) 1953 Def Failed
NWP-5 None 0 Native Estab
NWP-4b None 0 Native Estab
MED-IX None 2000 Def Failed

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


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

Fujinaga, Katsuaki (2006) Ecological studies on the life history of the neptune whelk Neptune arthritica, Memoirs of the Graduate School of Fisheries Science of Hokkaido University 50(1): 1-62

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>

Lee, Harry 2001-2015 Harry Lee's Florida Mollusca Checklists. <missing URL>

Miranda, Richard M.; Fujinaga, Katsuaki; Nakao, Shigeru (2008) Age and growth of Neptunea arthritica estimated from growth marks in the operculum, Marine Biology Research 4(3): 224-235

Shadrin, N. V.; Mironov, S. S., Golikov, A. N. (2002) A finding of the alive Neptunea arthritica (Bernardi, 1857) (Gastropoda, Buccinidae) in the Black Sea]., Ekologiya Morya 62: 29

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