Lacuna vincta

Researched By	Angus Jackson	Data Supplied By	MarLIN
Refereed by	Dr John Grahame
Taxonomy
Scientific name	Lacuna vincta	Common name	Banded chink shell
MCS Code	W292	Recent Synonyms	Lacuna carinata Kozloff, 1987.
Phylum	Mollusca	Subphylum
Superclass		Class	Gastropoda
Subclass	Prosobranchia	Order	Mesogastropoda
Suborder		Family	Littorinidae
Genus	Lacuna	Species	vincta
Subspecies
Additional Information	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, Campbell, 1994, Hayward & Ryland, 1995b, Ponder & Lindberg 1997, Taylor, 1996, Bieler, 1992
General Biology
Growth form	Turbinate	Feeding method	Herbivore
Mobility/Movement	Crawler	Environmental position	Epifaunal
Typical food types	Detritus, periphytic microalgae, macroalgae epidermis.	Habit	Free living
Bioturbator	Not relevant	Flexibility	None (< 10 degrees)
Fragility	Robust	Size	Small(1-2cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	Lacuna is a northern genus and the British Isles are near the southern edge of the range of this species. Lacuna vincta is rare in France but in north-east England densities have been recorded at 300 per square metre. In eastern Canada over 1,500 have been recorded per square metre. Adults die after spawning and very few can be found on the shore after April ( in southern Britain). The population is at a maximum in July (in southern Britain). Immediately after metamorphosis the young snail is about 0.55mm high. The brown bands on the shell develop following settlement. There is a very slight but not conclusive sexual dimorphism with the females being slightly larger. As the snail eats, the radula becomes worn down. Teeth are replaced through new growth. The form of the teeth varies depending on what the snail typically feeds on. This is important for determining feeding effectiveness. Sharp teeth are used for rasping and eating macroalgae whereas broader blunter teeth are used for scraping microalgae from the surface of plants. They do not graze algal film on rocks like the similar winkles.
Biology References	Hayward et al., 1996, Graham, 1988, Hayward & Ryland, 1995b, Martel & Chia, 1991a, Padilla et al., 1996, Fretter & Graham, 1994, Fretter & Manly, 1977, Grahame, 1977
Distribution and Habitat
Distribution in Britain & Ireland	Found on all British and Irish coasts.
Global distribution	Circumboreal extending south to Brittany.
Biogeographic range	Not researched	Depth range	Low shore to 40
Migratory	Seasonal (reproduction)
Distribution Additional Information	The species is found on a wide variety of coasts round the British Isles. It occasionally settles from the plankton as high as the mid tide level but is more typically found much further down the shore. The larvae settle out on a variety of algal species. The preferred species in the British Isles include Fucus serratus, Laminaria spp. and on red algal turf, particularly Lomentaria articulata. Also sometimes found on Zostera spp. Lacuna vincta has been recorded in salinities as low as 12-13 psu. Larval settlement from the plankton may occur in water velocities of 2.2m/s. There is a possible inshore migration by subtidal individuals in spring for breeding. The species requires considerable shelter from wave action and water flow. It acquires this shelter by selecting suitable habitats Exposure to adversely strong water currents may result in lifting of the foot and production of long sticky mucus threads allowing passive drifting in the water column to disperse to better conditions.
Substratum preferences	Algae	Physiographic preferences	Open coast, Sealoch, Ria / Voe, Estuary
Biological zone		Wave exposure	Moderately Exposed, Sheltered, Very Sheltered, Extremely Sheltered
Tidal stream strength/Water flow	Moderately Strong (1-3 kn), Weak (<1 kn), Very Weak (negligible)	Salinity	Full (30-40 psu), Variable (18-40 psu), Reduced (18-30 psu), Low (<18 psu)
Habitat Additional Information
AMBI Group (Borja et al., 2000)	II
Distribution References	Campbell, 1994, Hayward et al., 1996, Hayward & Ryland, 1995b, Fretter & Graham, 1994, Fretter & Manly, 1977, Martel & Diefenbach, 1993
Reproduction/Life History
Reproductive type	Gonochoristic	Developmental mechanism	Planktotrophic
Reproductive Season	All year	Reproductive Location	Insufficient information
Reproductive frequency	Annual protracted	Regeneration potential	No
Life span	<1 year	Age at reproductive maturity	<1 year
Generation time	<1 year	Fecundity	1,000-1,500 eggs per spawn
Egg/propagule size	Ca 100 µm	Fertilization type
Larvae/Juveniles Larval/Juvenile dispersal potential >10km Larval settlement period Peak May/June or September: See additional info. Duration of larval stage 1-6 months
Additional Information	In the field the species survives for a year or less. Survival rates are very low. Only 2-5 percent of the population will reach maturity. An estimate of the number of eggs per female per season is 53,500. Each spawn mass contains 1,000 - 1,500 eggs. The egg mass has a definite ring doughnut shape and the colour of the mass varies with diet. Individual egg size is around 100 microns. Development inside the egg takes 2.5 to 3.5 weeks. Spawning occurs throughout the year but there is a distinct peak. In southern Britain this peak is in winter resulting in main larval settlement in late May / early June. Further north settlement peaks in September. Cold temperatures may delay oviposition. Settlement is probably induced by organic properties of substrata beneficial to the adult rather than the presence of or exudate from other individuals of the species.
Reproduction References	Martel & Chia, 1991a, Grahame, 1994, Fretter & Graham, 1994, Fretter & Manly, 1977, Smith, 1973