Potamopyrgus antipodarum. Snout grey to black with pale bifid tip and, often, indistinct pale medial dorsal strip. White pigment spots confined to translucent body behind tentacles, apart from patch at base of the tentacles in front of eyes.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Potamopyrgus antipodarum. Sole of foot. White pigment spots on tentacle restricted to just in front of eyes. From slowly flowing freshwater pool at top of salting, Dee Estuary, Cheshire.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Potamopyrgus antipodarum. Darker dorsal surface of tentacle and fine white medial line indicated by arrow. Ribbing inside aperture is ctenidium (gill). From slowly flowing freshwater pool at top of salting, Dee Estuary, Cheshire

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Nearly all Potamopyrgus antipodarum, like this one, are female, lacking a penis behind the head. From stream just above tidal limit. September 2012. Llanfihangel y Traethau, Merionydd, Wales.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Potamopyrgus antipodarum shell found empty. Rusty colour may be result of oxidation of black deposit acquired in life. From freshwater pool with substrate of black anaerobic sand covered by few mm of reddish brown aerobic sand. Dee Estuary, Cheshire.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Translucent yellow-horn shell colour of Potamopyrgus antipodarum is often hidden by dark encrustation, except on the most recent whorl of still growing juveniles and sub-adults, such as this, shell height 3.8mm.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Potamopyrgus antipodarum. Shell heights 4.5mm to 1.1mm. Umbilical chink on smallest, closed on others. Arrow indicates rounded adapical angle of aperture standing out from final whorl. Thickened aperture lips on top three mature specimens.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

L. littorea. Head, tentacles and anterior of foot with transverse ‘tiger’ stripes on yellow flesh. Whitish triangle (blurred) in grey mantle cavity behind head is ctenidium (gill).

Species

Littorina littorea

Photographer / copyright holder

I.F. Smith

Shell height 14.8mm. Photographed September 2011

Potamopyrgus antipodarum. Specimen with spiral keel following the whorls. Keel overgrown with encrustation, so stout shell outline. Aperture closed by operculum. Shell height 4.5mm. Freshwater pool at top of salting, Dee Estuary, Cheshire.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

Potamopyrgus antipodarum. Shell heights 4.5mm to 1.1mm. All encrusted, except most recent whorl of growing juveniles. Top left specimen is keeled. From slowly flowing freshwater pool at top of salting, Dee Estuary, Cheshire.

Species

Potamopyrgus antipodarum

Photographer / copyright holder

I.F. Smith

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