Littorina Scutulata Class: Gastropoda Order: Littorinomorpha the Checkered Littorine Or Periwinkle Family: Littorinidae

Home , Littorina, Littorina plena, Littorina scutulata

Phylum: Mollusca Littorina scutulata Class: Gastropoda Order: Littorinomorpha The checkered littorine or periwinkle Family: Littorinidae

Taxonomy: Although originally described as (see Plate 378, Reid 2007). Two local separate species by Gould in 1849, Littorina species in the family Littorinidae, Littorina scutulata and Littorina plena were scutulata and L. plena, are morphologically synonymized in 1864 and only became very similar and differentiating them requires recognized as two separate species again in examination of penis morphology (see Fig. 1979 (Murray). Illustrations in this guideutilize B2, supplemental images on our website, and the same figures for both L. scutulata and L. Possible Misidentifications in this text). plena. Shell: The pattern on a typical L. scutulata has blue-green checks with a brown Description undertone and larger checks as opposed to Size: Littorina scutulata is generally larger the smaller checks of L. plena shells. than its morphologically similar congener, L. Individuals exhibit a range of shell patterns plena, with average height ~11.5 mm. and colors including a solid purple/black, Individuals can reach a shell size up to 17 although to a lesser degree than L. plena mm; this specimen (from Coos Bay) is 9 mm (Reid, 1996). Other reported differences in length (Fig. A1). At settlement, individuals include the presence of a basal ridge and a are ~ 350 µm. distinct light-colored basal band in the body Color: Color and patterns can be variable whorl of L. scutulata which is absent inL. but shell exterior is most commonly plena (Rugh, 1997; Hohenlohe and Boulding, checkered, and can cover a range of colors 2001). Shells should be wet to fully examine including dark brown, purple, green, black colors and patterns. and white. Other possible patterns include Shape: Shells are conical in shape, splotches, zig-zags, fine vertical and/or with four whorls, lacking a columellar groove horizontal etched banding, or various (inner lip) or chink. The shells of L. scutulata combinations of these. Never with strong are large and narrow, with a tall spire and spiral sculpture and many specimens are narrower aperture (Hohenlohe and Boulding eroded or encrusted with algae depending on 2001) (Fig. A1). Shell shape is known to vary the local habitat (e.g., protected shore vs. depending on local conditions; e.g., snails on wave-exposed shore). The Interior of the wave-exposed shores have shorter, thinner shell is nearly always purple (Keep and shells with a larger aperture (allows a larger Longstreth 1935). foot to help prevent dislodgment) whereas General Morphology: Shelled gastropods snails on protected shores have larger, can crawl and burrow using a muscular foot thicker shells with a smaller aperture (reduces and have a head with eyes and tentacles, a predation by crabs, Rugh 1997) mantle (which secretes the shell) and a Interior: Littorina spp. lack posterior radula that is composed of many teeth for or metapodial tentacles, having only cephalic tearing and rasping algae. Gastropods are tentacles (Carlton and Roth 1975) (see characterized by torsion, where the body dissection, Fig. A3). rotates early in development such that the Exterior: visceral mass (e.g., anus, mantle cavity) is Aperture: directly above the foot (rather than posterior Inner (Columella) and Outer Lip: to) (McLean 2007). The Littorinidea are Umbilicus: small-shelled snails with a rounded peristome

Tentacles: The tentacles of L. scutulata have (Keep and Longstreth 1935). A smaller incomplete transverse bands (often variety was formerly called L. rudis. It can alternating) with flecks (Fig. B3). be strongly striped, or rough and striated. It Eyes: is fairly common in salt marshes, and can Siphons: be up to 15 mm tall (Kozloff 1974a). Foot: Littorina (Algamorda) newcombiana Operculum: Solid, horny, and brown (= subrotundata) is a small, rare, salt marsh operculum with spiral lines originating in the littorine originally thought to be a freshwater bottom half (Fig. A1a). snail. It is light-colored, with four rounded Radula: whorls, usually striped; the shell is smooth, thin and covered with a brown periostracum Possible Misidentifications and the aperture is almost circular. It is only Snails in the genus Littorina (family about 5 mm long, and has a simple gap, Littorinidae) are very common members of (not a groove) between the whorl and the the intertidal, however their variation in shell columella (Keen and Coan 1974). It is morphology renders species difficult to found quite high in the intertidal area of the differentiate. Species level identification marsh. requires examination of the penis and pallial Littorina littorea, is an Atlantic oviduct (Reid 1996, 2007, Fig. B2 and species introduced into California bays supplemental images on our website). A 100 years ago; it is quite thick-shelled, similar but smaller genus of another family globose and colored brown to black, is Lacuna, the small 'chink' shell, which has with fine dark spiral bands (Abbott a groove, or chink, between the large whorl 1968). This species has not yet been and the columella; Littorina lacks this reported from Oregon (Carlton and groove. The Lacunidae are often found in Roth 1975). eelgrass, (Littorina is not), and are never in the upper intertidal area, as Littorina often is Ecological Information (Kozloff 1974a). Range: Type locality is Puget Sound, There are seven species in the Washington (Mastro et al. 1982). Known genus Littorina locally. Of those species, at range from Sitka, Alaska to Cabo San Lucas, least three have solid shell, and the Baja California. absence of columellar groove found in L. Local Distribution: Local distribution in plena. Littorina planaxis is an inhabitant of outer coast and bays including Coos Bay, the outer intertidal rocks, although found in South Slough, and the Siuslaw River, near Puget Sound, and in more marine parts of Florence (Matthews 1979). Oregon's estuaries (occasionally). It is stout Habitat: Snails are often found on rocks and and globose, and usually larger than L. pilings on both the rocky outer coast and scutulata (Brusca and Brusca 1978), with a protected shores, however, L. scutulata is broad, flat, polished columella (Keep and reported to be most abundant on the outer Longstreth 1935). Littorina planaxis is coast and is rarely, if ever, found in eelgrass essentially a southern form, although it does (Kozloff 1974a). Individuals are very tolerant occur occasionally in Puget Sound (Kozloff of near-terrestrial conditions (Brusca and 1974b), and its niche is generally taken over Brusca 1978). northwards at about Cape Arago, Oregon, Salinity: Found near full sea water on the by Littorina sitkana (Ricketts and Calvin open coast, as well as in conditions of 1971). Littorina sitkana, a fat, globose somewhat reduced salinity (Carlton and Roth littorine, has a rounded columella, strong 1975). This species does not penetrate upper spiral ridges on its whorls and can be white (and fresher) parts of estuary (Coos Bay). to black, but is often a yellowish brown

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/19869 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] The salinity tolerance ranges from 22–24 embryos per capsule may vary geographically (Brusca and Brusca 1978). (Hohenlohe 2002). The penis can be Temperature: Occurs over a wide range. observed by grasping the spire of a Tidal Level: Individuals are not found more submerged snail positioned aperture-up, than a few feet above high tide line but are providing a surface for the snail to grab onto found at higher levels in salt marshes (Kozloff (e.g., probe), and gently pulling away. The 1974b). Littorina spp. are ”just above the penis is orange-pink in color and is attached reach of the waves, along the shores of the just behind the base of the right tentacle. The entire bay" (San Francisco, California, penis in L. scutulata gradually tapers with a Packard 1918). very slight bifurcation at the tip (Fig. B2 and Associates: supplemental images on our website). The Abundance: Individuals are relatively pallial oviduct in females is also distinctive but common in rocky areas (Brusca and Brusca requires removal of the shell to be seen. 1978). Littornia plena and L. scutulata are Larva: probably the most common littorine in bays, Juvenile: as well, at least in more open coastal Longevity: The lifespan of L. scutulata is habitats. estimated to be at least 7 years (Behrens 1974). Life-History Information Growth Rate: Under favorable conditions, L. Reproduction: Dioecious (separate sexes) scutulata can increase its bodyweight by 7% with internal fertilization and most copulation in 2 months (Behrens, 1974). occurs in spring and summer, en masse, with Food: Herbivorous. Littorines use their a spawning season of April to early October. radula to rasp microscopic (e.g., Endocladia, Sexual maturity occurs when shells are ~2–3 unicellular green and blue green algae, mm in height (by 1 yr of age) and produce diatoms), and particularly macroscopic (e.g., negatively-buoyant pelagic egg cases, the Cladophora, Pelvetia, Rhodoglossum) algae morphology of which can be a reliable from rocks (Castenholz 1961; Dahl 1964). species indicator (Fig. B1 and supplemental Predators: Crabs, fish, birds, and predatory images on our website). At 12–14°C, L. gastropods. scutulata veligers hatch after 9 days with an Behavior: Individuals live in a “home initial size of ~145 μm. The planktonic period territory”, i.e., they stay in a small area near a of the planktotrophic veligers can last 4+ certain pool and "emerge by night, and weeks, although competency to settle can be submerge by day." (Abbott and Haderlie reached by 3 weeks (Hohenlohe 2002). 1980). Snails are generally active when Fecundity reports vary but L. scutulata has submerged and are often found clustered in been found to be capable of producing an groups and/or in crevices during the low tide. average of 7,000 eggs over a two-week period (Murray, 1979; Hohenlohe, 2002). Egg Bibliography cases contain pink embryos, although other 1. ABBOTT, D. P., and E. C. HADERLIE. colors in different regions have been reported 1980. Prosobranchia: marine snails. (Buckland-Nicks and Chia, 1973) and random In: Intertidal invertebrates of California. color variations within a region are sometimes R. H. Morris, D. P. Abbott, and E. C. encountered. Littorina scutulata capsules are Haderlie (eds.). Stanford University smaller than L. plena at ~800 μm in diameter, Press, Stanford, CA. with one rim noticeably larger than the other 2. ABBOTT, R. T. 1968. Seashells of (the smaller rim often being upturned slightly), North America; a guide to field and have ~1–11 embryos (compared to up to identification. Golden Press, New 47 embryos in L. plena) (Fig. B,1a and York. supplemental images on our website). A third 3. BRUSCA, G. J., and R. C. BRUSCA. egg case is also produced and exhibits a 1978. A naturalist's seashore guide. morphology with only one rim. The number of Mad River Press, Arcata, CA.

Valley, J. and T.C. Hiebert. 2015. Littorina scutulata. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to 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. 4. BUCKLAND, J., F. S. CHIA, and S. species of two prosobranch gastropod BEHRENS. 1973. Oviposition and species conformed by electrophoresis. development of two intertidal snails, Veliger. 24:239-246. Littorina sitkana and Littorina 14. MATTHEWS, R. 1979a. A scutulata. Canadian Journal of comparative study of preferred Zoology. 51:359-365. salinities among South Slough snails, 5. CARLTON, J. T., and B. ROTH. 1975. p. 8. Oregon Institute of Marine Phylum mollusca: shelled gastropods, Biology. p. 467-514. In: Light's manual: 15. —. 1979b. A comparative study of intertidal invertebrates of the central preferred salinities among South California coast. S. F. Light, R. I. Slough snails, p. Book: 2. Smith, and J. T. Carlton (eds.). 16. —. 1979c. A comparative study of University of California Press, preferred salinities among South Berkeley. Slough snails, p. Book: 2. Vol. Fall. 6. CASTENHOLZ, R. W. 1961. The 17. MCLEAN, J. H. 2007. Gastropoda, p. effect of grazing on marine littoral 713-739. In: The Light and Smith diatom populations. Ecology. 42:783- manual: intertidal invertebrates from 794. central California to Oregon. J. T. 7. DAHL, A. L. 1964. Macroscopic algal Carlton (ed.). University of California foods of Littorina planaxis Philippi and Press, Berkeley, CA. Littorina scutulata Gould. The Veliger. 18. —. 2017. Gastropoda, p. 713-753. In: 7:139-143. The Light and Smith manual: intertidal 8. HOHENLOHE, P. A. 2002. Life history invertebrates from central California to of Littorina scutulata and L-plena, Oregon. J. T. Carlton (ed.). University sibling gastropod species with of California Press, Berkeley, CA. planktotrophic larvae. Invertebrate 19. MURRAY, T. 1979. EVIDENCE FOR Biology. 121:25-37. AN ADDITIONAL LITTORINA 9. HOHENLOHE, P. A., and E. G. SPECIES AND A SUMMARY OF THE BOULDING. 2001. A molecular assay REPRODUCTIVE-BIOLOGY OF identifies morphological characters LITTORINA FROM CALIFORNIA. useful for distinguishing the sibling Veliger. 21:469-474. species Littorina scutulata and L. 20. PACKARD, E. L. 1918. Molluscan plena. Journal of Shellfish Research. fauna from San Francisco Bay. 20:453-457. Zoology. 14:199-452. 10. KEEN, A. M., and E. COAN. 1974. 21. REID. 2007. Littorina, p. 761-766. In: Marine molluscan genera of western The Light and Smith manual: intertidal North America: an illustrated key. invertebrates from central California to Stanford University Press, Stanford, Oregon. J. T. Carlton (ed.). University CA. of California Press, Berkeley, CA. 11. KOZLOFF, E. N. 1974a. Keys to the 22. RICKETTS, E. F., and J. CALVIN. marine invertebrates of Puget Sound, 1971. Between Pacific tides. the San Juan Archipelago, and Stanford University Press, adjacent regions. University of Stanford, California. Washington Press, Seattle. 23. RUGH, N. S. 1997. Differences in 12. —. 1974b. Seashore life of Puget shell morphology between the Sound, the Strait of Georgia, and the San Juan Archipelago and adjacent sibling species Littorina scutulata Regions. University of Washington and Littorina plena (Gastropoda: Press, Seattle and London. Prosobranchia). Veliger. 40:350- 13. MASTRO, E., V. CHOW, and D. 357. HEDGECOCK. 1982. Littorina scutulata and Littorina plena: sibling