Phylum: Mollusca Lacuna porrecta Class: Gastropoda, Caenogastropoda Order: Littorinimorpha The wide chink shell Family: Littorinoidea, Littorinidae, Lacuninae Description identified. Both are larger than our Oregon 1 1 Size: 2-4 mm high; /4 to /2 size of Littorina. species: Lacuna vincta (= carinata, = solidula) Color: white to golden brown, with some (Carlton and Roth 1975), is large, about 10 spiral marking; surface wrinkled, with fine, mm long, with 3-4 strong, smooth whorls, a wavy spiral striae (figs. 1, 4). No white band small umbilicus, a white columella, and a on inside of aperture, no carina (keel) on strong carina on the last whorl. Lacuna varie- largest whorl. gata is a tall, high-spired form, up to 6 mm Shell: high, found in eelgrass (Zostera); not de- Shape: broad, compact, globose, on- scribed in California keys (Ricketts and Calvin ly 3 whorls (fig 1); shell thin, outer lip 1971). L. variegata has a spreading outer lip, ‘effuse’ (extended); aperture semi-lunar. a wide chink, and zig zag markings (Keep Columella: flattened (fig 4): genus 1935). Lacuna. The species most like L. porrecta and Umbilicus: chink is large, with a often found with it is Lacuna marmorata, the sharp ridge (fig 3); this groove between marbled chink shell, usually brown and white, whorl and columella is an important key but with a carina on the large whorl, a narrow character of the genus Lacuna. columeilar groove, and often with a white Operculum: ‘paucispiral’; flattened stripe inside the base of the aperture (Carlton on one side (fig 2). and Roth 1975). It has been found in Coos Body: Lacuna species have metapodial ten- Bay (Keen et al 1942), and hybridizes with tacles, which Littorina lack (fig 5). other Lacuna spp., (Friday Harbor) (Morris et al 1980). Possible Misidentifications Adult Lacunidae can be differentiated Ecological Information from Littorinidae by their much smaller size, Range: Bering Sea to San Diego, California metapodial tentacles, and chiefly by their (Packard 1918). umbilical fissure or chink which Littorinidae Local Distribution: Coos Bay, several sta- lack. (Littorinidae have a columella flush with tions: South Slough (Keen and Doty 1942). the large whorl). Lacuna are often found in Habitat: in algae, eelgrass (Zostera), or eelgrass; Littorina almost never are. around its roots; in tidepool algae at lower lit- There are several species of Lacuna torine level (Keen et al 1942). on the Pacific coast: Salinity: Lacuna unifasciata is more turbinate Temperature: genus Lacuna essentially a than globose, and has a sharp carina or keel cold water form; few tropical species. around its largest whorl. It is a southern spe- Tidal Level: mid- and low intertidal levels and cies, its northern boundary being probably at subtidally; never in upper reaches (Kozloff Monterey Bay, California (Carlton and Roth 1974b). 1975). Associates: hermit crabs, amphipods, littori- Two Puget Sound species have been ne snails; en-crusted with bryozoans. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Unknown. 1983. Lacuna porrecta. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to 140 Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Abundance: not common. from San Francisco Bay. 14:199-452. 7. RICKETTS, E. F., and J. CALVIN. 1971. Life-History Information Between Pacific tides. Stanford University Reproduction: Lacuna variegata has eggs Press, Stanford, California. like life preservers: yellow, about 5 mm di- ameter (Kozloff 1974b). Updated 1983 Larva: Juvenile: Longevity: Growth Rate: 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. Phylum Mollusca: Shelled Gastropods, p. 467-514. In: Light's manual; intertidal in- vertebrates 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 gas- tropods of Cape Arago, Oregon. Studies in Zoology. 13. 3. KEEP, J. and J. Longstreth (eds). 1935. West coast shells; a description in famil- iar 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 Uni- versity 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 inverte- brates of California. Stanford University Press, Stanford, California. 6. PACKARD, E. L. 1918. Molluscan fauna A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] .