Juga Plicifera Class: Gastropoda, Caenogastropoda

Juga plicifera Class: Gastropoda, Caenogastropoda

Order: Caenogastropoda Graceful keeled horn snail Family: Cerithioidea, Semisulcospiridae

Description Eggs: single or in small groups (Clarke 1981) Size: “small to medium”, to 35 mm long (not shown). (Clarke 1981). Illustrated specimen, Possible Misidentifications (Columbia River), (incomplete as drawn): 16 The superfamily Cerithiacea includes mm long (fig. 1). many common marine snail genera - Bittium, Color: shell pale dusky grey; animal with Cerithiopsis, Metaxis, Cerithidea, etc. These dark transverse stripes on head and tenta- are also turriform, with a smooth, unfolded cles (not shown) (Clarke 1981). Periostra- columella. Cerithidea californica, the Califor- cum blackish or brown. nia horn snail, is quite similar to J. plicifera, Shell: but is no longer found north of Tomales Bay, Shape: turriform (many-whorled, California (McDonald 1969). This species oc- slender spired), dextrally coiled. About 15 curs in estuaries and bays, in mud, and under whorls; early ones usually corroded (Clarke boards and debris. It has low axial ribs, not 1981). high C-shaped plicae; its operculum has mul- Sculpture: 10 to 12 axial plicae tiple spirals, not just a few. It tolerates brack- (raised ribs) on each whorl. (Plicae also de- ish water, but not fresh water. scribed as sigmoid (C-shaped) growth rests, The genus Juga is distinguished by its or as varices.) Fine collabral cords (i.e. con- lack of the apertural notch common to many forming to shape of outer lip at an earlier of the Cerithiacea genera. Juga is separated growth stage (Clarke 1981)) (fig. 1). from Goniopsis and Pleurocera partly by its Columella: smooth (not twisted); with eggs, which are single or in small groups, not broad canal below it (Clarke 1981) (fig. 2). massed, and by its genitalia (the males have Aperture: rounded below, acutely an- no penis) (Clarke 1981). Pleurocera, found in gled above (Clarke 1981); outer lip simple, the eastern U.S., has a twisted columella, not entire, not notched (figs. 1, 2). a smooth one (Ward and Whipple 1966). Go- Operculum: typical of Prosobranchia: niobasis, to which J. plicifera belonged until ovate, corneous (horny), with spiral growth recently (Taylor 1966), is shorter than Juga, lines; "paucispiral," i.e. with few whorls - and has fewer whorls (Clarke 1981). J. pficif- about 3 (Clarke 1981) (fig. 3). era is the only species of the genus in the Body: (not shown); mantle border not northwestern U.S. (Clarke 1981). Also synon- fringed (Ward and Whipple 1966); tentacles ymized with J. plicifera is J. sificula, which long, very narrow, tapering, with dark was formerly believed to be a different spe- stripes; boot short, wide. Males lack penis cies because it is stouter, with stronger ribs (Clarke 1981). and a wider apical angle (Henderson 1929). Radula: (not shown); central tooth J. acutifilosa Stearns, the sharp lined without basal denticles (Ward and Whipple river shell of northern California lakes, has 1966): family Pleuroceridae. 7 teeth/row, in strong spiral keels (Keep 1935), and is proba- pattern of 2-1-1-2, each multicuspid. bly extinct (Clarke 1976).

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. 1988. Juga plicifera. 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.

Ecological Information 4. KEEP, J. B. J. L., and ED. 1935. West Range: Olympic Peninsula, Washington; coast shells; a description in familiar terms Columbia River and other drainages south of principal marine, fresh-water, and land to California. Possibly Vancouver Island. mollusks of the United States, British Co- Local Distribution: Columbia River, lower lumbia, and Alaska, found west of the Si- reaches; also Tahkenich Lake, near Flor- erra. Calif., Stanford University Press; ence, Oregon (Douglas Co.). London, H. Milford, Oxford University Habitat: muddy-sand bottoms of small and Press, Stanford University. medium lakes; also slow flowing streams 5. MACDONALD, K. B. 1969. Molluscan fau- (Clarke 1981). Likes cool clear water, green nas of Pacific coast salt marshes and tidal algae (Keep 1935). creeks. The Veliger. 11:399-405. Salinity: considered a freshwater species, it 6. TAYLOR, D. W. 1966. Summary of North is also found in the lower Columbia River. American Blancan nonmarine mollusks. Temperature: Malacologia. 4:1-172. Tidal Level: 7. WARD, H. B., and G. C. WHIPPLE. 1963. Associates: Fresh-water biology. John Wiley & Sons; Abundance: New York. Life-History Information Updated 1988 Reproduction: family is oviparous (Henderson 1929); no external verge (male organ). Larva: Juvenile: Longevity: Growth Rate: Food: most of family are bottom feeders; some feed on plants, algae, dead vegetation (Clench and Turner 1956). Predators: Behavior: Bibliography 1. CLARKE, A. H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 2. CLENCH, W. J., and R. D. TURNER. 1956. Review of freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwannee River. Bulle- tin of the Florida Museum. 3:97-240. 3. HENDERSON, J. 1929. Non-marine Mol- lusca of Oregon and Washington. [University of Colorado], Boulder, Colo.