BIOTIC Species Information for Helcion pellucidum
Researched byDr Harvey Tyler-Walters Data supplied byMarLIN
Refereed byDr David McGrath
General Biology
Growth formConical
Feeding methodHerbivore
Mobility/MovementTemporary attachment
Environmental positionEpifaunal
Typical food types%Laminaria hyperborea%, %Laminaria digitata%, %Alaria esculenta%, %Sacchoriza polyschides%, %Fucus serratus%, and when young %Himanthalia elongata% and %Mastocarpus stellatus%. HabitFree living
BioturbatorNot relevant FlexibilityNone (< 10 degrees)
FragilityRobust SizeSmall(1-2cm)
Height Growth Rate1-2 mm/month
Adult dispersal potentialVery limited (<1m) DependencyIndependent
General Biology Additional InformationGrowth is rapid in summer, autumn and winter but slow in winter. Population studies suggest that few individuals survive to their second year (Fretter & Graham, 1976; Graham & Fretter, 1947). Vahl (1971) noted growth irregularities or 'checks' in the shell of specimens from Norway, which he suggested were caused by the interrupted growth of the mantle edge when the adult was retracted in response to severe wave action during heavy storms.

Adults can recolonize vacant fronds (McGrath, 1997), perhaps via the surface of the substratum or by mucus rafting, and if dislodged adults can right themselves and be carried to neighbouring plants by currents by secreting a mucus 'sail' (Vahl ,1983).

Kain & Svendsen (1969) provide pictures of Helcion pellucidum on blades of Laminaria hyperborea together with the cavities grazed in the fronds and in holdfasts. Kain & Svendsen (1969) noted that in Norwegian populations severe grazing by Helcion pellucidum may result in perforation of blades by autumn (before new blades develop) and in some cases grazing where the blade and stipe meet may 'cut off' the blade.
Biology References Fish & Fish, 1996, Fretter & Graham, 1976, Graham & Fretter, 1947, McGrath, 1992, McGrath, 1997, Vahl, 1983, Fretter & Graham, 1994, Kain & Svendsen, 1969, Vahl, 1971,
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