01 Peringia ulvae

Shells with deep sutures and tumid whorls.

1 to 3: males (have penes).

4 to 6: females or immature (lack penes).

7 to 11: juveniles.

Body whorl decreases from 66% of juvenile 2 mm high shell to 51% of adult 6 mm high.

Aperture decreases from 55% of 2 mm high juvenile to 42% of 6 mm high adult.

Heights 2 mm to 6 mm. Dee Estuary, England, August 2011.

 

Full DESCRIPTION BELOW

PDF available at www.researchgate.net/publication/375322835_Peringia_ulvae...

Sets of OTHER SPECIES at: www.flickr.com/photos/56388191@N08/collections/.

 

Peringia ulvae (Pennant, 1777)

Synonyms: Turbo ulvae Pennant, 1777; Hydrobia ulvae (Pennant, 1777); Paludestrina ulvae (Pennant, 1777); Paludina ulvae (Pennant, 1777); Rissoa ulvae (Pennant, 1777); Sabanaea ulvae (Pennant, 1777); Hydrobia stagnalis (some authors); Paludestrina stagnalis (some authors); Rissoa barleei Jeffreys;

Current taxonomy: WoRMS www.marinespecies.org/aphia.php?p=taxdetails&id=151628

Vernacular names: Laver spire shell; Laver wreath shell [Pennant]; Cogwrn y lafwr [Welsh];

 

GLOSSARY BELOW

 

Shell description

Usually up to 6 mm high, exceptionally 10 mm. Conical, body whorl proportion declines with growth from about 66% of 2mm high shell to about 50% of 6mm high shell 1Pu flic.kr/p/ekg7Qo , but shape can vary independently of size 2Pu flic.kr/p/ekamWD & 3Pu flic.kr/p/ekg7K7 . No sculpture, surface smooth, unless encrusted or eroded 4Pu flic.kr/p/ekamSP . Many sources, such as Graham (1988) and Fish & Fish (1989) state that whorls are almost flat in profile, but deep sutures and tumid whorls predominate in some populations 5Pu flic.kr/p/ekg7FU & 08Pu flic.kr/p/ekg7Dw and it is this form which is illustrated by Pennant (1777) in his original description from the Dee Estuary in Wales. Spire may be slightly translucent, revealing dark body inside 6Pu flic.kr/p/ekg7Fj . Whitish-brown, yellow-brown to dark brown 2Pu flic.kr/p/ekamWD (photos in water, duller in air). Surface may have green 4Pu flic.kr/p/ekamSP , black 7Pu flic.kr/p/ekamQt , brown or reddish 5Pu flic.kr/p/ekg7FU encrustations from the environment. Aperture about 55% of 2mm high shell, about 40% of 6mm high shell 1Pu flic.kr/p/ekg7Qo ; acute adapical angle 7Pu flic.kr/p/ekamQt . Base of aperture can be rounded or drawn out slightly 8Pu flic.kr/p/ekg7Dw . Tear-shaped spiral operculum 7Pu flic.kr/p/ekamQt , often concealed by overlapping opercular lobe when creeping 9Pu flic.kr/p/ekg7CY . No open umbilicus, but usually small closed umbilical groove 8Pu flic.kr/p/ekg7Dw .

 

Body description

Flesh yellowish/whitish grey, marked black/brown and yellow/white 10Pu flic.kr/p/ekg7Co .

Long translucent whitish to greyish cephalic tentacles with yellow or white pigment flecks and black subterminal band 11Pu flic.kr/p/ekamMc . Left tentacle shorter with enlarged sensory cilia in oblique rows 12Pu flic.kr/p/ekg7By . Eye on anterior of yellowish or pinkish white patch 13Pu flic.kr/p/ekamMa at base of tentacle. Bifid extendible trunk-like snout 14Pu flic.kr/p/ekamLV with transverse furrows 15Pu flic.kr/p/ekg7AJ . Some snouts brown-black with light tip 15Pu flic.kr/p/ekg7AJ , others patterned with transverse bands 16Pu flic.kr/p/ekg7Af .

Upper surface of foot pale grey with yellow or white freckles Pu17 flic.kr/p/ekamK8 ; anterior edge bilaminate 15Pu flic.kr/p/ekg7AJ . Sole translucent white, sometimes showing freckles of upper surface 18Pu flic.kr/p/ekamK8 . Foot anterior can expand into prehensile lobes 18Pu flic.kr/p/ekamK8 .

Single small pallial tentacle 6Pu flic.kr/p/ekg7Fj on right. Large yellow-flecked sickle-shaped penis behind head of male 19Pu flic.kr/p/ekamJP . Adult female 10Pu flic.kr/p/ekg7Co and juveniles lack visible organ behind head when body fully extended. Ovipositor 13Pu flic.kr/p/ekamMa on right side of female. Tip of grey ctenidium occasionally seen when body fully extended 12Pu flic.kr/p/ekg7By .

 

Key identification Features

Peringia ulvae (Pennant, 1777) )

1) Adapical angle of aperture acute 7Pu flic.kr/p/ekamQt. Maximum height 6 mm, occasionally 10 mm.

2) Translucent tentacles with black subterminal band and, usually, many yellow/ white pigment flecks 11Pu flic.kr/p/ekamMc. Left tentacle thicker and less smooth than right tentacle 12Pu flic.kr/p/ekg7By .

3) Salinity 5-40‰, usually estuarine mudflats or saltings with open tidal access.

 

Similar species

Potamopyrgus antipodarum (J.E. Gray, 1843)

1) Adapical angle of shell aperture rounded 20Pu flic.kr/p/2pb7Wwp . Maximum height 5.5 mm, rarely 7 mm.

2) Translucent pale greyish tentacles often with fine white medial line, no subterminal black mark and few/no opaque white flecks apart from basal patch in front of eye 21Pu flic.kr/p/2pb68AE .

3) Mainly in flowing, fresh water but also in brackish ditches and lagoons up to 17 ‰ salinity.

 

Assiminea grayana Fleming, 1828

1) Adapical angle of aperture acute 22Pu flic.kr/p/2pb2yVm . Maximum height 6 mm.

2) Short blackish grey tentacles with eye visible dorsally near tip 23Pu flic.kr/p/2pbajX7 .

3) Near high water mark on saltings and tidal rivers, usually moist, but not often submerged except just after high spring tide or flooding.

 

Melarhaphe neritoides (Linnaeus, 1758)

1) Adapical angle of shell aperture acute 24Pu flic.kr/p/2pbaTTt . Maximum height 9 mm.

2) Long cephalic tentacles, grey-black dorsally with thin pale median line. Eye at centre of whitish disc at base of tentacle 25Pu flic.kr/p/2pbaU9U .

3) At and above EHWS on exposed rocky shores.

 

Ecrobia ventrosa (Montagu, 1803)

1) Adapical angle of shell aperture rounded. Maximum shall height 4.5 mm.

2) Grey or colourless translucent tentacles lack black transverse band, but may have longitudinal dusky streak near tip 26Pu flic.kr/p/2pcXXRQ .

3) Usually lagoons, no opening to sea, but seawater seepage in at high tide, salinity 1-36 ‰, soft substrate and vegetation.

 

Hydrobia acuta neglecta Muus, 1963

1) Adapical angle of aperture rounded. Maximum shell height 4 mm.

2) Tentacles grey of varying darkness; tips covered with variable black cone often with a pale intrusion into base of cone 27Pu flic.kr/p/2pcXYpy .

3) Usually lagoons with no opening to sea, salinity 10-35 ‰, soft substrate and vegetation.

 

Heleobia charruana (d'Orbigny, 1841)

1) Shell shape similar to non-tumid form of P. ulvae but usually white or greyish with a vague silky gloss, translucent sometimes showing viscera; may have dark mineral encrustation. Adapical angle of aperture acute. Maximum shell height in Europe 6.4 mm 28Pu flic.kr/p/2pcXXDW.

2)Tentacles translucent whitish with no black markings. Body colour varies white to brownish, but usually paler than P. ulvae and similar species 28Pu flic.kr/p/2pcXXDW

3) Alien, euryhaline (34‰ - 4‰ or less) species from Uruguay, present in tidal rivers and estuaries in Belgium, Netherlands and England (Thames, abundant). Sometimes with P. ulvae or Potamopyrgus antipodarum.

 

Habits and Ecology

Abundant on firm bare intertidal wet muddy sand and mud on estuaries and saltings 29 Pu flic.kr/p/2mVVn5A at salinities 5- 40 p.p.t.; individuals may struggle to adjust to very large rapid salinity changes. Also on gravel or broken clay-slate with silt, on Ulva, and in pools with bare soft substrate; usually with tidal access. Often at densities 5 000 –9 000 /sq.metre, and occasionally to 42 000 /sq.metre. At all shore levels, varying with local substrate conditions; avoids putrid mud lacking oxygen, and semi-liquid mud (e.g. parts of Severn Estuary). If on open coast, usually some freshwater inflow.

Crawls when substrate moist or covered in calm water. No waves detectable on sole when crawls horizontally; probably moves by means of cilia on sole. Direct monotaxic waves detectable on posterior of foot when crawls up vertical glass. Leaves 2 mm wide track with mucus trail 29Pu flic.kr/p/2mVVn5A on sand or mud. Swings trunk-like snout from side to side while crawling to feed on small organic particles, diatoms and bacteria. Individual grain of sand can be held by bifid snout while radula grazes it 30Pu flic.kr/p/ekamFx . In soft mud, lies buried horizontally except for aperture from which body extends. When submerged, may float feeding under water surface with aid of a mucus raft 30Pu flic.kr/p/ekamFx which traps diatoms etc. from the neuston. Rafting snails, and dried juveniles with air trapped in aperture, dispersed by currents and waves, so colonises rapidly, e.g. upriver if drought causes short term increase in salinity. When mud and pools dry out, buries self and becomes dormant. Also buries self if water turbulent. Breeds all months, peak varies with location. Spawn 31Pu flic.kr/p/ekg7qs ; gelatinous hemispherical masses covered in sand, containing up to 25 eggs floating in albuminous fluid, attached to shells of other individuals; up to 90% carry spawn masses at peak breeding times. Short veliger stage, sometimes suppressed (?) or escapes capture as stays near substrate (?). Velum small and only slightly bilobed. Each female lays about 300 eggs in a breeding season; small number in comparison with other species e.g. Littorina littorea, but comparatively good survival rate of about 10% beyond 1mm shell height. Maximum growth rate April-July. Most die before 2 years old.

Important part of the ecosystem in estuaries and saltings, providing food for birds (especially shelduck Pu 32 flic.kr/p/2rECM5S ), fish and many parasites, altering the substrate with its spindle-shape faecal pellets and affecting the abundance of the micro-organisms it feeds on. Associated fauna; other euryhaline spp. such as Macoma balthica and Scrobicularia plana. Not with terrestrial spp. except when these colonise dried out mud with dormant P. ulvae buried in it. Sometimes close to, but not usually intermingled with, Assiminea grayana at HWS level of saltings (no intermingling found on Dee Estuary, but possible report from Lincolnshire).

 

Distribution and status

North Norway to Senegal, including Baltic and Mediterranean. GBIF map www.gbif.org/species/4361879 . Abundant on estuaries and saltings all round Britain and Ireland. NBN UK map species.nbnatlas.org/species/NHMSYS0001702153

 

Acknowledgements

For help and use of images I gratefully thank Simon Matthews, Ron Offermans, Ben Rowson, Simon Taylor, Peter Topley and Ton Van Haaren.

 

Links and references

Fretter, V. and Graham, A. 1962. British prosobranch molluscs: their functional anatomy and ecology. London, Ray Society. (Has index of species.)

 

Fretter, V. and Graham, A. 1994. British prosobranch molluscs: their functional anatomy and ecology. Revised edition. London, Ray Society. (Much new material but lacks index of species.)

 

Graham, A. 1988. Molluscs: prosobranch and pyramidellid gastropods. Synopses of the British Fauna (New Series) no.2 (Second edition). Leiden, E.J. Brill/Dr. W. Backhuys. 662 pp.

 

Green, J. 1968. The biology of estuarine animals. London. Sidgwick & Jackson.

 

Pennant, T. 1812 British Zoology 4. London (original description from Dee Estuary specimens) archive.org/stream/britishzoolog04pennpage/558/mode/2up

 

Rowson, B., Powell, H., Willing, M., Dobson, M. and Shaw, H. 2021. Freshwater snails of Britain and Ireland. Telford, FSC.

 

Van Haaren, T., Worsfold, T.M., Stelbrink, B., Collado, G.A., Gonçalves, I.C.B., Serra, W.S., Scarabino, F., Gittenberger, A. & Gittenberger, E. 2021. Heleobia charruana (Gastropoda, Truncatelloidea, Cochliopidae), a South American brackish water snail in northwest European estuaries. Basteria 85 (1): 82–91. Leiden. www.researchgate.net/publication/351248434_Heleobia_charr....

 

Yonge, C.M. and Thompson, T.E. 1976. Living marine molluscs. London.

 

Glossary

‰ = (salinity) parts salt per thousand parts water (brackish < 30‰).

adapical = towards the apex of the shell.

aperture = mouth of gastropod shell; outlet for head and foot.

bifid = divided into two parts by a cleft.

body whorl = most recent and largest whorl of a gastropod shell which, apart from viscera in the spire, accommodates the withdrawn body.

 

cephalic = (adj.) of the head.

cilia = (sing. cilium) microscopic linear extensions of membrane which can act as sensory organs or move in rhythmic waves to create locomotion.

 

ctenidium = comb-like molluscan gill; usually an axis with a row of filaments either side.

 

diatom = microscopic aquatic alga with siliceous cell-walls.

direct = (of waves) moving over gastropod foot in same direction as snail travelling.

 

euryhaline = able to tolerate a wide variation in salinity.

mantle = (a.k.a. pallium) sheet of tissue which secretes the shell, covers the viscera and forms a cavity in gastropods.

 

molecular sequencing = laboratory technique for determining the exact sequence of nucleotides, or bases, in a DNA molecule.

 

monotaxic = (of waves) single series across whole width of gastropod foot.

 

neuston = community of micro-organisms living in the surface film of water.

 

operculum = horny plate used to close shell aperture.

opercular = (adj.) of the operculum.

ovipositor = an unpigmented tract on the right side of a female’s body which carries ova out of the mantle cavity for deposition (usually on the shell of another P. ulvae).

 

pallial tentacle = tentacular extension of the edge of the pallium (mantle).

 

penes = plural of penis, male copulatory organ.

radula = ribbon of chitinous teeth extruded on a tongue-like structure (odontophore) to rasp food.

 

salting = area of salt tolerant vascular plants rooted in sediment between MHW and EHWS. [Preferred synonym for “saltmarsh” as much of a salting is not marshy].

 

spire = all whorls of a gastropod shell, except the final body whorl.

subterminal = a short distance from the end.

suture = groove or line where whorls adjoin.

tumid = bulging, distended, swollen, distinctly convex.

umbilicus = cavity up axis of some gastropod shells, open as a hole or chink on base of shell, often sealed over.

 

umbilical chink = narrow slit-like umbilicus, often inconspicuous.

 

veliger = shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).

 

Done