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:

Monodonta labio is a marine snail with a wide Indo-Pacific distribution, from Madagascar and the Persian Gulf to northern Australia, the Yellow Sea, China, and south-central Japan (Huang 2001; Iijima 2001; Australian Biological Resources Study 2007; Academy of Natural Sciences of Philadelphia 2013). It was found on newly transplanted Pacific oysters in Samish Bay, Washington by Kincaid in 1947 (cited by Hanna 1966 and Carlton 1979), but a population did not become established. To our knowledge, there are no further reports of this snail outside its native range.

North American Invasion History:

Invasion History on the West Coast:

Monodonta labio was reported to be abundant on newly transplanted oysters in Samish Bay, Washington by Kincaid in 1947 (cited by Hanna 1966; Carlton 1979), but a population did not become established. There are no further records of this snail in North American waters.


Monodonta labio is a medium-sized marine snail, with a thick, conical, turban-like shell, sculpted with strong spiral ridges which are broken up into lines of rounded knobs. The body whorl is somewhat swollen, while the previous (penultimate) whorl is less so. The whorls have a rounded keel. The apex is sharp, but it softened or worn away in adults. The columella has a large blunt tooth, projecting into the aperture, while the inner edge of the outer lip is lined by rounded knobs. The lining of the interior of the aperture is nacreous. The color of the exterior of the shell is reddish brown, dark brown, or pale brown, marked with spiral dashes of white, cream, or pink. Adult snails reach 25-40 mm long. Characteristic habitats include the rocky areas of the lower intertidal, shallow subtidal and subtidal regions. Description from Iijima 2001, Australian Biological Resources Study (2007), and Appeltans et al. 2013.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Prosobranchia
Order:   Archaeogastropoda
Family:   Trochidae
SubFamily:   Monodontinae
Genus:   Monodonta
Species:   labio


Trochus labio (Linnaeus, 1758)
Monodonta melaurchelonis (Philippi, None)
Monodonta tuberculata ( A. Adams, 1853)

Potentially Misidentified Species



Monodonta labio is a marine snail found in rocky intertidal and shallow subtidal regions. Sexes are separate and this snail reproduces by broadcast spawning, with planktotrophic development (Takada 1996). Females mature at about 6-10 mm, at around 1 year of age (Takada 1996, Iijima 2001). Monodonta labio grazes on microalgae in the intertidal and shallow subtidal zones of rocky shores and coral reefs (Takada 1996).


General HabitatOyster ReefNone
General HabitatRockyNone
General HabitatMangrovesNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Tidal RangeMid IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Length (mm)6Size at maturation, Japan (Takada 1996)
Maximum Length (mm)30Australian Biological Resources Study 2007
Broad Temperature RangeNoneWarm-temperate-Tropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Monodonta labio is not established in North American waters and has no reported impacts.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-3b None 0 Native Estab
NWP-2 None 0 Native Estab
EAS-I None 0 Native Estab
EAS-III None 0 Native Estab
EAS-II None 0 Native Estab
NWP-3a None 0 Native Estab
EAS-VII None 0 Native Estab
EAS-VIII None 0 Native Estab
AUS-I None 0 Native Estab
AUS-II None 0 Native Estab
AUS-XIV None 0 Native Estab
AUS-XII None 0 Native Estab
EAS-VI None 0 Native Estab
CIO-IV None 0 Native Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1947 Def Failed
P293 _CDA_P293 (Strait of Georgia) 1947 Def Failed
AUS-X None 0 Native Estab
AUS-III None 0 Native Estab
AUS-XI None 0 Native Estab
EA-III None 0 Native Estab
AUS-XIII None 0 Native Estab
NWP-4a None 0 Native Estab
AG-1 None 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Academy of Natural Sciences of Philadelphia 2002-2016a Malacology Collection Search.

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

Appeltans, W. et al. 2011-2015 World Registry of Marine Species.

Australian Biological Resources Study 2007 Species Bank <i>Monodonta labio</i>.

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

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.

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

Iijima, Akiko (2001) Growth of the intertidal snail, Monodonta labio (Gastropoda, Prosobranchia) on the Pacific Coast of central Japan, Bulletin of Marine Science 68(1): 27-36

Takada, Yoshitake (1996) Vertical migration during the life history of the intertidal gastropod Monodonta labio on a boulder shore, Marine Ecological Progress Series 130: 117-123

Takada, Yoshitake (1996) Vertical variation in fecundity of the intertidal gastropod Monodonta labio caused by different growth rates between tidal zones, Ecological Research 11: 371-379

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database. <missing description>