Hydrobia ulvae

Researched By	Lizzie Tyler	Data Supplied By	University of Sheffield
Refereed by	This information is not refereed.
Taxonomy
Scientific name	Hydrobia ulvae	Common name	Laver spire shell
MCS Code	W385	Recent Synonyms	Peringia ulvae
Phylum	Mollusca	Subphylum
Superclass		Class	Gastropoda
Subclass	Prosobranchia	Order	Mesogastropoda
Suborder		Family	Hydrobiidae
Genus	Hydrobia	Species	ulvae
Subspecies
Additional Information	Also 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 form	Turbinate	Feeding method	Surface deposit feeder, Sub-surface deposit feeder
Mobility/Movement	Swimmer, Crawler, Burrower, Drifter	Environmental position	Epifaunal
Typical food types	Detritus, periphytic microalgae.	Habit	Free living
Bioturbator	Not relevant	Flexibility	Low (10-45 degrees)
Fragility	Robust	Size	Very small(<1cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
Additional Information	The 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 & Ireland	Found on all British and Irish coasts
Global distribution	Atlantic, English Channel, North Sea and Baltic. Insufficient detail available to map distribution.
Biogeographic range	Not researched	Depth range	0 - 20 m
Migratory	Non-migratory / Resident
Distribution Additional Information	Often 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 preferences	Sandy mud, Muddy sand, Mud	Physiographic preferences	Open coast, Sealoch, Ria / Voe, Estuary, Isolated saline water (Lagoon), Enclosed coast / Embayment
Biological zone	Upper Littoral Fringe, Lower Littoral Fringe, Upper Eulittoral, Mid Eulittoral, Lower Eulittoral, Sublittoral Fringe, Upper Infralittoral, Lower Infralittoral	Wave exposure	Sheltered, Very Sheltered, Extremely Sheltered, Ultra Sheltered
Tidal stream strength/Water flow	Moderately Strong (1-3 kn), Weak (<1 kn), Very Weak (negligible)	Salinity	Variable (18-40 psu), Low (<18 psu), Full (30-40 psu), Reduced (18-30 psu)
Habitat Additional Information
AMBI Group (Borja et al., 2000)	III
Distribution References	Graham, 1988, Fretter & Graham, 1994, Clay, 1960, Barnes, 1981, Anderson, 1971, Hayward & Ryland, 1990
Reproduction/Life History
Reproductive type	Gonochoristic	Developmental mechanism	Planktotrophic, Lecithotrophic
Reproductive Season	March to October	Reproductive Location	Insufficient information
Reproductive frequency	Annual protracted	Regeneration potential	No
Life span	1-2 years	Age at reproductive maturity	<1 year
Generation time	Insufficient information	Fecundity	26.5
Egg/propagule size		Fertilization type	Internal
Larvae/Juveniles Larval/Juvenile dispersal potential >10km Larval settlement period Insufficient information Duration of larval stage 11-30 days
Additional Information	The 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