BIOTIC Species Information for Balanus crenatus
Researched byNicola White Data supplied byMarLIN
Refereed byProf. Alan J. Southward
Scientific nameBalanus crenatus Common nameAn acorn barnacle
MCS CodeR77 Recent SynonymsNone

PhylumCrustacea Subphylum
Superclass ClassMaxillopoda
SubclassCirripedia OrderThoracica
SuborderBalanomorpha FamilyBalanidae
GenusBalanus Speciescrenatus

Additional InformationNo text entered
Taxonomy References Rainbow, 1984, Bassindale, 1964,
General Biology
Growth formConical
Feeding methodPassive suspension feeder
Active suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpifaunal
Typical food typesZooplankton and other organic particles of a suitable size, such as detritus and phytoplankton. HabitAttached
BioturbatorNot relevant FlexibilityNone (< 10 degrees)
FragilityRobust SizeSmall(1-2cm)
HeightInsufficient information Growth Rate4.4 mm/month
Adult dispersal potentialNone DependencyIndependent
General Biology Additional InformationBalanus crenatus has a calcareous base, while Semibalanus balanoides has a membranous base.
Balanus crenatus feeds by extending thoracic appendages called cirri out from the shell to filter zooplankton from the water. In the absence of any current, the barnacle rhythmically beats the cirri. When a current is present Balanus crenatus holds the cirri fully extended in the current flow. Barnacles feed most during spring and autumn when plankton levels are highest. Little if any feeding takes place during winter, when barnacles rely on stored food reserves. Feeding rate is important in determining the rate of growth.
Barnacles need to moult in order to grow. Frequency of moulting is determined by feeding rate and temperature. Moulting does not take place during winter when phytoplankton levels and temperatures are low.
Balanus crenatus is hermaphroditic and grows up to 25mm in diameter.
Biology References Rainbow, 1984, Barnes et al., 1963, Bassindale, 1964,
Distribution and Habitat
Distribution in Britain & IrelandAll coasts of Britain & Ireland, and offshore in the North Sea and Celtic Sea.
Global distributionNortheast Atlantic from the Arctic to the west coast of France as far south as Bordeaux; east and west coasts of North America and Japan.
Biogeographic rangeNot researched Depth rangeInsufficient information
MigratoryNon-migratory / Resident   
Distribution Additional InformationBalanus crenatus is a widespread species that occurs at quite high latitudes in the Arctic. It colonizes a wide range of substrata, attaching to any hard substrata, molluscs and their dead shells (Southward, pers. comm.), often as an initial colonizing species. Densely packed colonies occur particularly in areas exposed to strong tidal streams where few other epifauna survive. It can also be found attached to carapaces of the Norway lobster or Dublin Bay prawn (Nephrops norvegicus) and other crustaceans.
Balanus crenatus may have been misidentified as Solidobalanus fallax in shallow waters lying to the south of the UK. The deep water record of Gruvel (noted in Southward, 1998) is an error (Southward, pers. comm.). Balanus crenatus and Solidobalanus fallaxcolonize different substrates and also occur in different temperatures. Solidobalanus fallax occurs in warmer water on shells, false corals, seaweeds and other soft substrata, including plastic bags and synthetic netting (Southward, pers. comm.).

Substratum preferencesBedrock
Artificial (e.g. metal/wood/concrete)
Gravel / shingle
Large to very large boulders
Small boulders
Physiographic preferencesOpen coast
Offshore seabed
Strait / sound
Ria / Voe
Enclosed coast / Embayment
Biological zoneLower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Wave exposureExtremely Exposed
Very Exposed
Moderately Exposed
Very Sheltered
Extremely Sheltered
Tidal stream strength/Water flowVery Strong (>6 kn)
Strong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
SalinityFull (30-40 psu)
Reduced (18-30 psu)
Variable (18-40 psu)
Low (<18 psu)
Habitat Preferences Additional Information
Distribution References Rainbow, 1984, Barnes, 1953, Barnes et al., 1963, JNCC, 1999, Bassindale, 1964, Southward, 1998,
Reproduction/Life History
Reproductive typePermanent hermaphrodite
Developmental mechanismPlanktotrophic
Reproductive SeasonFebruary to September Reproductive LocationAs adult
Reproductive frequencyAnnual episodic Regeneration potential No
Life span1-2 years Age at reproductive maturity<1 year
Generation time<1 year FecundityInsufficient information
Egg/propagule sizeInsufficient information Fertilization type
Larval/Juvenile dispersal potential>10km Larval settlement periodInsufficient information
Duration of larval stage11-30 days   
Reproduction Preferences Additional Information
  • Balanus crenatus is an obligate cross-fertilizing hermaphrodite. Nauplii larvae are released from the barnacle between February and September, with peaks in April and late summer when phytoplankton levels are highest. However, release is not synchronised with the spring algal bloom, unlike Semibalanus balanoides.
  • Nauplii larvae are planktotrophic and develop in the surface waters. They pass through six nauplii stages before eventually developing into a cyprid larva. Cyprid larvae are specialised for settlement. They drift and swim in the plankton before selecting a suitable substratum for settlement and metamorphosis. Peak settlement occurs in April and declines until October. Metamorphosis usually takes place within 24 hours of settlement.
  • Barnacles grow rapidly except in winter. April-settled individuals may release larvae the same July and reach full size before their first winter. Individuals that settled later reach maximum size by the end of spring the following year (Rainbow, 1984).
  • Balanus crenatus has a life span of 18 months (Barnes & Powell, 1953). Growth rate varies greatly with the degree of current flow and the presence of silt. Balanus crenatus populations attached to Nephrops norvegicus grew only 2mm in 4 months, whereas populations on rafts grew at 0.2mm per day. This reduction in growth in epizoic populations is attributed to the higher presence of silt and reduction in water currents (Barnes & Bagenal, 1951).
Reproduction References Rainbow, 1984, Barnes & Powell, 1953, Barnes & Bagenal, 1951,
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