BIOTIC Species Information for Hydrobia ulvae
Researched byLizzie Tyler Data supplied byUniversity of Sheffield
Refereed byThis information is not refereed.
Scientific nameHydrobia ulvae Common nameLaver spire shell
MCS CodeW385 Recent SynonymsPeringia ulvae

PhylumMollusca Subphylum
Superclass ClassGastropoda
SubclassProsobranchia OrderMesogastropoda
Suborder FamilyHydrobiidae
GenusHydrobia Speciesulvae

Additional InformationAlso known as the mud snail. Many synonyms have been used in the past but Peringia ulvae is the only one used recently. Hydrobia ulvae is now the standard usage although Peringia is often used as a sub-genus of Hydrobia. Hydrobia neglecta has a black 'v' mark near the tip of the tentacles.
The taxonomy of the Gastropoda has been recently revised (see Ponder & Lindberg 1997, and Taylor 1996). Ponder & Lindberg (1997) suggest that Mesogastropoda should be included in a monophyletic clade, the Caenogastropoda.
Taxonomy References Howson & Picton, 1997, Graham, 1988, Fretter & Graham, 1994, Fish, 1979, Clay, 1960, Fish & Fish, 1977(a), Taylor, 1996, Ponder & Lindberg, 1997,
General Biology
Growth formTurbinate
Feeding methodSurface deposit feeder
Sub-surface deposit feeder
Environmental positionEpifaunal
Typical food typesDetritus, periphytic microalgae. HabitFree living
BioturbatorNot relevant FlexibilityLow (10-45 degrees)
FragilityRobust SizeVery small(<1cm)
HeightInsufficient information Growth RateInsufficient information
Adult dispersal potential100-1000m DependencyIndependent
General Biology Additional InformationThe males can be distinguished by a visible penis. Frequently found in very high densities - has been recorded up to 300,000 per square metre. Growth rate varies with time of year and with degree of parasite infestation. Parasite infestation is believed to cause increased growth rates, gigantism and altered morphology in this species. Parasitised snails may reach up to 9mm in height. Parasitism also affects behaviour, slowing locomotion and reducing burrowing activity. The feeding method of Hydrobia ulvae can also be classified as 'microbrowser'.
Biology References Graham, 1988, Fretter & Graham, 1994, Clay, 1960, Sola, 1996, Huxham et al., 1995, Jensen & Mouritsen, 1992, Hayward & Ryland, 1990, Julie Bremner, unpub data,
Distribution and Habitat
Distribution in Britain & IrelandFound on all British and Irish coasts
Global distributionAtlantic, English Channel, North Sea and Baltic. Insufficient detail available to map distribution.
Biogeographic rangeNot researched Depth range0 - 20 m
MigratoryNon-migratory / Resident   
Distribution Additional InformationOften found as high as the high level strand line in a dried blanket of green algae. They appear to be dead but rapidly revive when returned to more suitable conditions. Hydrobia ulvae does not undertake any true migration but considerable dispersal is possible through floating at the surface using a mucous raft. A cycle of climbing, floating and crawling up and down the shore has been hypothesised. Work by Barnes (1981) suggests however that climbing is simply part of normal browsing behaviour.

Substratum preferencesSandy mud
Muddy sand
Physiographic preferencesOpen coast
Ria / Voe
Isolated saline water (Lagoon)
Enclosed coast / Embayment
Biological zoneUpper Littoral Fringe
Lower Littoral Fringe
Upper Eulittoral
Mid Eulittoral
Lower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Wave exposureSheltered
Very Sheltered
Extremely Sheltered
Ultra Sheltered
Tidal stream strength/Water flowModerately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
SalinityVariable (18-40 psu)
Low (<18 psu)
Full (30-40 psu)
Reduced (18-30 psu)
Habitat Preferences Additional Information
Distribution References Graham, 1988, Fretter & Graham, 1994, Clay, 1960, Barnes, 1981, Anderson, 1971, Hayward & Ryland, 1990,
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismPlanktotrophic
Reproductive SeasonMarch to October Reproductive LocationInsufficient information
Reproductive frequencyAnnual protracted Regeneration potential No
Life span1-2 years Age at reproductive maturity<1 year
Generation timeInsufficient information Fecundity26.5
Egg/propagule size Fertilization typeInternal
Larval/Juvenile dispersal potential>10km Larval settlement periodInsufficient information
Duration of larval stage11-30 days   
Reproduction Preferences Additional InformationThe longevity of this species is debatable. Hydrobia ulvae may live up to five years in aquaria and over four years in the arctic. Various studies have suggested that it lives from just over 1 year up to 2.5 years. Individuals hatching from eggs laid in spring can breed in autumn, whereas those hatching in autumn over-winter before breeding in spring. The species is gonochoristic and sperm transfer occurs by copulation. Minimum egg hatching time has been recorded as five days. There is considerable conflicting evidence over the developmental mechanism of the larvae of this species. Some workers (Fish & Fish, 1977) have found the planktonic stage to last up to four weeks and development to be entirely planktotrophic. Others (Pilkington, 1971) have found the planktonic stage to be completely absent with a nonfeeding benthic larva that metamorphoses after just two days. Snails producing planktotrophic forms have several (7-22) smaller eggs that hatch into veliger larvae at around 150 microns. Snails producing lecithotrophic forms lay fewer (3-7) larger eggs. Maximum number of eggs recorded from one mass is 50. The timing of the breeding season varies with latitude. In the north of Scotland there is a short spawning period in Spring. In populations further south the spawning period is more protracted and is split into two peaks (spring and autumn). Age at maturity Eggs are laid preferentially on the shells of live individuals of this species but also on empty shells and grains of sand. The egg mass acquires a protective layer of sand grains.
Reproduction References Fretter & Graham, 1994, Barnes, 1988, Clay, 1960, Barnes, 1990, Fish & Fish, 1974, Anderson, 1971, Sola, 1996, Pilkington, 1971, Eckert, 2003, Julie Bremner, unpub data,
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