Digitized 2010 – Last Updated 1979 – E-mail corrections to oimbref@uoregon.edu 
 
 
 
 
 
 
Description 
Size—2-4 mm high; 1/4 to 
1/2 size of Littorina. 
Color—white to golden brown, with some 
spiral marking; surface wrinkled, with fine, 
wavy spiral striae (figs. 1, 4). No white band 
on inside of aperture, no carina (keel) on 
largest whorl. 
Shell Shape—broad, compact, globose, only 
3 whorls (fig 1); shell thin, outer lip ‘effuse’ 
(extended); aperture semi-lunar. 
Umbilicus—chink is large, with a sharp ridge 
(fig 3); this groove between whorl and 
columella is an important key character of the 
genus Lacuna. 
Columella—flattened (fig 4): genus Lacuna. 
Operculum—‘paucispiral’; flattened on one 
side (fig 2). 
Animal—Lacuna species have metapodial 
tentacles, which Littorina lack (fig 5). 
 
Possible Misidentifications 
     Adult Lacunidae can be differentiated from 
Littorinidae by their much smaller size, 
metapodial tentacles, and chiefly by their 
umbilical fissure or chink which Littorinidae 
lack. (Littorinidae have a columella flush with 
the large whorl). Lacuna are often found in 
eelgrass; Littorina almost never are. 
     There are several species of Lacuna on 
the Pacific coast: 
     Lacuna unifasciata is more turbinate than 
globose, and has a sharp carina or keel 
around its largest whorl. It is a southern 
species, its northern boundary being probably 
at Monterey Bay, California (Carlton and Roth 
1975). 
     Two Puget Sound species have been 
identified. Both are larger than our Oregon 
species: Lacuna vincta (= carinata, = solidula) 
(Carlton and Roth 1975), is large, about 10 
mm long, with 3-4 strong, smooth whorls, a 
small umbilicus, a white columella, and a 
strong carina on the last whorl. Lacuna 
variegata is a tall, high-spired form, up to 6 
mm high, found in eelgrass (Zostera); not 
described in California keys (Ricketts and 
Calvin 1971). L. variegata has a spreading  
 
 
 
outer lip, a wide chink, and zig zag markings 
(Keep 1935). 
     The species most like L. porrecta and 
often found with it is Lacuna marmorata, the 
marbled chink shell, usually brown and white, 
but with a carina on the large whorl, a narrow 
columeilar groove, and often with a white 
stripe inside the base of the aperture (Carlton 
and Roth 1975). It has been found in Coos 
Bay (Keen et al 1942), and hybridizes with 
other Lacuna spp., (Friday Harbor) (Morris et 
al 1980). 
 
Ecological Information 
Range—Bering Sea to San Diego, California 
(Packard 1918). 
Local Distribution—Coos Bay, several 
stations: South Slough (Keen and Doty 1942). 
Habitat—in algae, eelgrass (Zostera), or 
around its roots; in tidepool algae at lower 
littorine level (Keen et al 1942). 
Salinity— 
Temperature—genus Lacuna essentially a 
cold water form; few tropical species. 
Tidal Level—mid- and low intertidal levels 
and subtidally; never in upper reaches 
(Kozloff 1974b). 
Associates—hermit crabs, amphipods, 
littorine snails; en-crusted with bryozoans. 
 
Quantitative Information 
Weight— 
Abundance—not common. 
 
Life History Information 
Reproduction—Lacuna variegata has eggs 
like life preservers: yellow, about 5 mm 
diameter (Kozloff 1974b). 
Food—family is herbivorous. 
Predators—in eelgrass: seastar Lepasterias. 
Few fishes eat Lacuna (Morris et al 1980). 
Behavior—it waddles as it moves one side of 
foot, then the other. 
 
Bibliography 
1. CARLTON, J. T., and B. ROTH. 1975. 
Lacuna porrecta  
The wide chink shell (Carpenter, 1863) 
Phylum:  Mollusca   
   Class:  Gastropoda 
      Order:  Mesogastropoda 
         Family:  Lacunidae 
   
Digitized 2010 – Last Updated 1979 – E-mail corrections to oimbref@uoregon.edu 
Phylum Mollusca: Shelled Gastropods, 
p. 467-514. In: Light's manual; 
intertidal invertebrates of the central 
California coast. S. F. Light, R. I. 
Smith, and J. T. Carlton (eds.). 
University of California Press, 
Berkeley. 
2. KEEN, A. M., E. COAN, and C. L. 
DOTY. 1942. An annotated check list 
of the gastropods of Cape Arago, 
Oregon. Studies in Zoology. 13. 
3. KEEP, J. and  J. Longstreth (eds). 
1935. West coast shells; a description 
in familiar terms of principal marine, 
fresh-water, and land mollusks of the 
United States, British Columbia, and 
Alaska, found west of the Sierra. 
Calif., Stanford University Press; 
London, H. Milford, Oxford University 
Press, Stanford University. 
4. KOZLOFF, E. N. 1974b. Seashore life 
of Puget Sound, the Strait of Georgia, 
and the San Juan Archipelago. 
University of Washington Press, 
Seattle & London. 
5. MORRIS, R. H., D. P. ABBOTT, and 
E. C. HADERLIE. 1980. Intertidal 
invertebrates of California. Stanford 
University Press, Stanford, California. 
6. PACKARD, E. L. 1918. Molluscan 
fauna from San Francisco Bay. 
14:199-452. 
7. RICKETTS, E. F., and J. CALVIN. 
1971. Between Pacific tides. Stanford 
University Press, Stanford, California. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Digitized 2010 – Last Updated 1979 – E-mail corrections to oimbref@uoregon.edu