Hydrobia ulvae feeding under the water surface with the support of a mucus raft which traps the neuston. Grains of sand trapped in the mucus. Hydrobia on the left holding a grain between the lobes of bifid snout while grazing off the micro-organisms. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae on Enteromorpha. H. ulvae is named after Ulva on which it can also be found. It moves through the weed with the aid of prehensile lobes on the front of its foot. Shell 4.2mm high, deep suture form. Mouth of Dee Estuary. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Some mud is too soft for Hydrobia ulvae to crawl on, but they may be overlooked when they lie buried with just their heads and feet protruding to feed on the surrounding surface. Several were found in this mud on the Severn Estuary. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Over a million H. ulvae live on the wet sand in this image of a small part of the mouth of the Dee Estuary, Cheshire. (Random sample had 4737 / sq. metre) When the water dries up they retreat below the sand surface. All examined had deep shell sutures. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae. Arrow indicates black subterminal band on the left tentacle which is thicker and less smooth than the right tentacle. Shell height 5.4 mm. Mouth of Dee Estuary, Cheshire. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae, shell height 6mm. If a male is placed on its left side in water, the penis (arrowed) is briefly visible as the animal stretches out to right itself. Extend exposure by holding the spire with forceps, or by inserting it into plasticine. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae patterned heads. Left 4.5mm (yellow markings) and upper right 3.5mm (white markings) from Aust, Severn Estuary 22.7p.p.th.. Lower right from Dee Estuary, 33p.p.t., where it was only patterned specimen among 58 others with all-black heads. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae. Green algae on shell. Un-patterned black/dark brown head with light bifid tip. Grey dorsal surface on foot. Shell height 5.4mm. From puddle in wet sand at mouth of Dee Estuary. Salinity 33p.p.t. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae. Black arrow; umbilical chink. Adapical end of aperture pointed. Base of aperture (grey arrows) elongated on right specimen (height 4.4mm), more rounded with thicker lip on left specimen (height 5mm). Deep sutures. Mouth of Dee, Cheshire. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
Hydrobia ulvae sole of foot. Shell height 4mm. Aust, Severn Estuary, salinity 22.7 p.p.t. Species Hydrobia ulvae Photographer / copyright holder I.F. Smith
