Phylum: Mollusca Aplysiopsis enteromorphae Class: Gastropoda, Heterobranchia, Euthyneura, Tectipleura Order: Sacoglossa Smith’s unwashed-looking sacoglossan Family: Plakobranchoidea, Hermaeidea Description 14 mm x 15 mm; eggs become paler as they Size: 5 to 25 mm long (Behrens 1980; Trow- develop (Goddard 1984; Gonor 1961). Eggs bridge 1993a); most are 10 mm (Goddard average 66 µ in diameter (fig. 3) and are ≤ 4 1985), some to 15 mm (Gonor 1961). Illus- mg (Trowbridge 1993a). Hydrophilic trated specimen (Coos Bay) 15 mm long. (Trowbridge 1993a). Color: Yellowish white, with greenish black Possible Misidentifications patches; animal can be almost black: much Sacoglossans differ from most Nudi- local variation (Gonor 1961). Head uniform branchia in their lack of a circlet of gills, and in color, dorsal cerata white or yellow tipped; by their rolled, rather than solid rhinophores. rhinophores uniform in color, not veined. They also lack oral tentacles, and have a uni- Body: Oblong, flat bottomed; no oral tenta- seriate radula (Thompson 1976). Sacoglos- cles or parapodial lobes, but with prominent sans are herbivorous. There are other saco- tail (fig. 1). No circlet of external gills: order glossans with dorsal cerata and rolled rhino- Sacoglossa. Secretion of mucus and viscous phores, in two families: Limapontiidae and white fluid when disturbed (Trowbridge Hermaeidae. 1993b). In the family Hermaeidae there are two Rhinophores: Prominent; rolled, not solid: species (McDonald 2007): order Sacoglossa (fig. 1). (Basal part rolled, Hermaea vancouverensis is a bay form distal part simple (Kozloff 1974)). Color uni- like Aplysiopsis, but very small (5 mm). It has form, without system of lines. a triangular brown patch anterior to the rhino- Foot: No parapodial lobes (which fold over phores, and a brown collar anterior to the body in some species); foot extends to form cerata. Its habitat is in the sea grass Zostera tail (Gonor 1961); narrowly triangular (Clark Hermaea oliviae (=Aplysiopsis oliviae, 1982). =Hermaeina oliviae), a rare and probably Cerata: Dorsal processes: spindle shaped, more southern species than A. enteromor- inflated, white tipped; 8 - 15 rows of 2 to 4 phae. It is up to 10 mm long, and has a Y- per row (Gonor 1961) (fig. 1); slightly flat- shaped dorsal mahogany line running back tened (Clark 1982). from the rhinophores. Gills: None: order Sacoglossa. The Limapontiidae are represented lo- Eyes: Black, small, but conspicuous; deep cally by at least four species (McDonald set, at bases of rhinophores (fig. 1). 2007): Genital Openings: Two, on right behind rhi- Placida dendritica (=Hermaea ornata) nophore (fig. 1). nd rd has long rhinophores and an elongate tail (like Anus: Slightly raised, near 2 and 3 cera- Aplysiopsis), but its cerata are long and not ta, with black spot and near renal opening lumpy, and its ground color is pale yellow with (Gonor 1961) (fig. 1). Anus on midline at a distinct veining of olive. It is quite small (to 8 “shoulders” not on a long tube. mm), and is often found in the green algae Eggs: Yellow to white, in "C" shaped string Bryopsis and Codium in the rocky intertidal. 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] Bork, E. and Kenton, K. 2017. Aplysiopsis enteromorphae. 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 Biol- ogy, Charleston, OR. Olea hansineensia (formerly in Olei- thoe valida, Grandidierella japonica, alga En- dae) is greenish brown. It has only 10 or teromorpha, isopods, and prosobranch gas- fewer white tipped cerata; its rhinophores tropods (Trowbridge 2002). are short. Weight: 4-227 mg (wet weight) (Trowbridge Stiliger fuscovittatus differs from most 1993b). sacoglossans in having solid simple rhino- Abundance: Probably the most abundant phores; it is small (to 3 mm) and whitish, sacoglossan of this coast (Goddard 1985; with rust markings. It lives in the red alga Gonor 1961); seasonally common (Goddard Polysiphonia. 1984; Goddard 1985; Steinberg 1963); only Alderia modesta (which see) has re- sacoglossan species that fills the niche of eat- duced rhinophores and an anus on a long ing green filamentous algae (Trowbridge et al. posterior tube like a ceras. It lives in Salicor- 2011). nia marshes. Life-History Information Ecological Information Reproduction: Hermaphroditic; produces a Range: Ketchikan, Alaska to San Diego, single generation per year (Trowbridge 2002); California; also in Gulf of California (Behrens (illustrated) eggs found July (Coos Bay) with 1980; Trowbridge 1993b). recruitment in June (Trowbridge 1993b). Lays Local Distribution: Coos County: South eggs on Enteromorpha strands continuously Slough, in Metcalf Preserve, and South in lab; lays eggs on Mastocarpus papillatus in Cove, (Trowbridge 2002). high tidepools and on Enteromorpha in mud- Habitat: Sacoglossans are typically restrict- flats (Trowbridge 2002); larvae emerge as ed to certain algae species (Gonor 1961; free swimming veligers and have long plank- Thompson 1976). In bays, Aplysiopsis is tonic feeding phase (Gonor 1961). Embryonic commonly found on the green filamentous period 7 days at 15-17 °C.; larvae without algae Rhizoclonium and Enteromorpha. It eyespots at hatching; newly hatched veligers also likes quiet, shallow mud-bottomed bays have shell about 113 µ long (Goddard 1984). which have Zostera at low tide level and Sexually mature a few days after hatching bare mudflats above (San Juan Island). In (Trowbridge 1993b). Coos Bay it is found on bare mudflats near Larva: Enteromorpha beds. Also found seasonally Juvenile: on green algae Cladophora and Chaetomor- Longevity: pha in high to mid intertidal pools on open Growth Rate: 10 mg/week or 1.4 mg/day coast rocky shores, as well as in kelp hold- (Trowbridge 1993b). fasts (Goddard 1984; Goddard 1985; Keen Food: Prefers Rhizoclonium, Urospora, and Coan 1974). Not found in areas with Cladohphora columbiana, Cladophora tricho- high levels of wave action (Trowbridge toma, Chaetomorpha linum, Chaetomorpha 1993b). aerea (Trowbridge 1993a, 2002); prefers Salinity: Collected at 30. Chaetomorpha over Cladophora (Trowbridge Temperature: 10-15 °C. 1993a); rejects Enteromorpha (Gonor 1961). Tidal Level: On San Juan Island, found at Feeds by slitting each filament cell with a rad- 0.0 tide level; in Coos Bay at +5.0 ft. MLLW. ular tooth, then moving on to the next cell Intertidal to 10 m subtidally (Keen and Coan (Gonor 1961) (fig. 4). Suctorial feeding 1974). (Trowbridge 1993a). Starts at the distal tip Associates: In Coos Bay, amphipods Ampi- and moves toward the proximal end of each 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] filament (Trowbridge 1993a). Seattle & London. Predators: Rarely consumed by most pred- 8. MCDONALD, G.R. 2007 Sacoglossa and ators, but eaten by mudflat crabs and Dun- Nudibranchia, p. 797-798. In: Light and geness crabs in experiments (Trowbridge Smith manual: intertidal invertebrates from 1994). central California to Oregon. 4th ed. J.T. Behavior: Some sacoglossans emit un- Carlton (ed.). University of California pleasant repellants from cerata to repel Press, Berkeley. predators (Thompson 1976). When dis- 9. STEINBERG, J. E. 1963. Notes on the turbed, it reduced surface pH, became acid- opisthobranchs of the west coast of North ic, and waved and autotomized cerata America. The Veliger. 6:68-73. (Trowbridge 1994). Attracted to conspecifics; 10. THOMPSON, T. E. 1976. Biology of opis- found living near one another (Trowbridge thobranch molluscs. Ray Society, London. 1993b). 11. TROWBRIDGE, C.D. 1993a. Feeding ecology of the ascoglossan opisthobranch Bibliography Aplysiopsis enteromorphae (Cockerell & 1. BEHRENS, D. W. 1980. Pacific coast nu- Eliot): Patterns of distribution and impact dibranchs: a guide to the opisthobranchs on tidepool-dwelling algae. Journal of Ex- of the northeastern Pacific. Sea Chal- perimental Marine Biology and Ecology. lengers, Los Osos, Calif. 169:233-257. 2. CLARK, K.B. 1982. A new Aplysiopsis 12. TROWBRIDGE, C.D. 1993b. Population (Opisthobranchia: Hermaeidae) from structure of two common species of as- central Flordia, with a brief summary of coglossan (= sacoglossan) opisthobranchs the ceratiform families of the order as- on the central coast of Oregon, USA. The coglossa (= sacoglossa). Bulletin of Ma- Veliger. 36:99-106. rine Science. 32:213-219. 13. TROWBRIDGE, C.D. 1994. Defensive re- 3. GODDARD, J. H. R. 1984. The opistho- sponses and palatability of specialist her- branchs of Cape Arago, Oregon, with bivores: Predation on NE Pacific ascoglos- notes on their biology and a summary of san gastropods. Marine Ecology Progress benthic opisthobranchs known from Ore- Series. 105:61-70. gon. Veliger. 27:143-163. 14. TROWBRIDGE, C.D. 2002. Northeastern 4. ——. 1985. Personal communication. Or- Pacific sacoglossan opisthobranchs: Natu- egon Institute of Marine Biology, Charles- ral history review, bibliography, and pro- ton, Or. spectus. The Veliger. 45:1-24. 5. GONOR, J. J. 1961. Observations on the 15. TROWBRIDGE, C.D., Y.M. HIRANO, Y.J. biology of Hermaeina smithi, a sacoglos- HIRANO, K. NISHIDA, and K. SUDO. san opisthobranch from the west coast of 2011. North-west Pacific sacoglossan North America. The Veliger. 4:85-98. guild associated with filamentous green 6. KEEN, A. M., and E. COAN. 1974. Ma- algae (Family Cladophoraceae and Family rine molluscan genera of Western North Boodleaceae). Marine Biodiversity Rec- America: an illustrated key. Stanford Uni- ords. 4:1-15. versity Press, Stanford, California. Updated 2017 7. KOZLOFF, E. N. 1974. Keys to the ma- E. Bork and K. Kenton rine invertebrates of Puget Sound, the San Juan Archipelago, and adjacent re- gions.