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:

Guildfordia yoka was described from Japan, but ranges south to the Philippines and northern Australia. It inhabits deep water, down to 270 m, on silt or clay bottoms (Academy of Natural Sciences of Philadelphia 2006-2012). This shell is highly prized by collectors for its beauty. One living specimen was collected in 1912 at the mouth of San Francisco Bay in 34 m of water (Packard 1918, cited by Carlton 1979), a puzzling record.

North American Invasion History:

Invasion History on the West Coast:

The only record of Guildfordia yoka in North America is a single living specimen in a dredge collection off the Golden Gate in 1912 (Packard 1918, cited by Carlton 1979). This snail is unlikely to be found in fouling, and its larvae would be unlikely (though possible) candidates for ballast water transport (Carlton 1979).


Guildfordia yoka is a marine turban snail. It has a flattened, dextrally coiled, conical shell, with 7-8 whorls covered with pimple-like bumps, terminating in a low obtuse spire. The remarkable feature of this species is the presence of eight radiating, backward-curving spines, each about equal to the shell diameter. The underside of the shell is convex and the umbilicus is large, but shallow and open, and the aperture is a narrow oval. This shell reaches a diameter of 100 mm. The color of the shell is purplish red. Description from: Jousseaume 1899, Oliver 2004, and Web images.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Prosobranchia
Order:   Archaeogastropoda
Superfamily:   Trochacea
Family:   Turbiniidae
SubFamily:   Astraeinae
Genus:   Guildfordia
Species:   yoka


Astralium yoxa (None, None)

Potentially Misidentified Species

Guildfordia triumphans
(=Astralium triumphans)



Guildfordia yoka is a marine turban snail, characteristic of deep, soft-sediment habitats. We have been unable to find information on its biology or life history.


General HabitatUnstructured BottomNone
General HabitatRockyNone
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Maximum Width (mm)100Oliver 2004
Broad Temperature RangeNoneWarm temperate-Tropical
Broad Salinity RangeNoneEuhaline, a deep-water species (Carlton 1979)

General Impacts

Guildfordia yoka is known from only a single specimen in US waters and no impacts are known from its occurrence. The shell is valued by collectors worldwide.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-V Northern California to Mid Channel Islands 1912 Def Failed
EAS-I None 0 Native Estab
EAS-III None 0 Native Estab
AUS-I None 0 Native Estab
P090 San Francisco Bay 1912 Def Failed
CIO-IV None 0 Native Estab
NWP-2 None 0 Native Estab
AUS-II None 0 Native Estab
AUS-IV None 0 Native Estab
NWP-3a None 0 Native Estab
AUS-III None 0 Native Estab
NWP-3b 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.

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

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

Jousseaume, D. (1899) [Description of a new shell- Guildfordia yoka, Le Naturaliste 21: 48-49

Oliver, A. P. H. (2004) <missing title>, Firefly Books, Buffalo NY. Pp. <missing location>