Hydrobia ulvae | The Conchological Society of Great Britain and Ireland

<p><em>Hydrobia ulvae</em> (Pennant, 1777)</p>

Thousands of Hydrobia ulvae darkening the sand at the mouth of Dee Estuary, Cheshire. Active at low tide in film of water; note tracks in foreground. If film dries, snails burrow into surface completely, or partially.They support flocks of Shelducks.

Species

Photographer / copyright holder

Peter Topley

H. ulvae. Female; pallial oviduct extends along right side to tentacle. Eye on anterior of pinkish patch. Darkly shaded band on tentacle in front of eye. Left tentacle thicker and rougher than right tentacle. 6.5mm shell height. Upper Dee Estuary, Flints.

Species

Photographer / copyright holder

I.F. Smith

Hydrobia ulvae. Shell height 5mm. Female; no penis behind tentacles. 3 ribs of grey ctenidium just visible over top edge of body at rear (magnify image to see). From large muddy salting pool on upper Dee Estuary, Flintshire, salinity 29 p.p.t. (variable).

Species

Photographer / copyright holder

I.F. Smith

Hydrobia ulvae. Height in mm and sex, top left to bottom right : 6.5 f, 5.5 m, 5 f, 5.5 f, 4.5 m, 4.4 m. Upper Dee Estuary, salinity 29 p.p.t. Majority; shallow sutures and flattened whorls. A few (2 bottom right); deep sutures & small but adult.

Species

Photographer / copyright holder

I.F. Smith

Hydrobia ulvae. Height in mm and sex, top left to bottom right : 6.5 f, 5.5 m, 5 f, 5.5 f, 4.5 m, 4.4 m. Upper Dee Estuary, salinity 29 p.p.t. Majority; shallow sutures and flattened whorls. A few (2 bottom right); deep sutures & small but adult.

Species

Photographer / copyright holder

I.F. Smith

Smallest specimen 4mm high, largest 6mm high. Top row; males (have penes), bottom row; females (lack penes, usually mature by 4mm). All from a population with deep shell sutures at the mouth of the Dee Estuary, Cheshire.

Species

Photographer / copyright holder

I.F. Smith

Hydrobia ulvae. Shell heights 4.5mm. Penis arrowed. From large muddy salting-pool on upper Dee Estuary, Flints. 29 p.p.t. Animals stretching against restraint of spire inserted in plasticine.

Species

Photographer / copyright holder

I.F. Smith

To examine the parts of the body usually concealed inside the shell, hold the specimen, in water of correct salinity, on its back or side with forceps, or by pressing the spire into plasticine.

H. ulvae. Arrows indicate sutures.Left: 6.5mm high, shallow sutures & flattened whorls, salting pool, upper Dee Estuary, Flints., 29 p.p.t. (variable). Right: 6mm high, deep sutures & rounded whorls, wet sand at mouth of Dee Estuary, Cheshire, 33 p.p.t.

Species

Photographer / copyright holder

I.F. Smith

Hydrobia ulvae aperture and operculum. Arrow indicates pointed adapical end of aperture. From salting pool, salinity 22.7p.p.t., Aust, Severn Estuary. Most specimens from this site with sulphide-rich anaerobic mud had extensive black encrustation.

Species

Photographer / copyright holder

I.F. Smith

Sand covered spawn masses deposited on shells by other H. ulvae. Top right of image; two masses at larger scale, removed from shells to show white ova within. Mouth of Dee Estuary.

Species

Photographer / copyright holder

I.F. Smith

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