BIOTIC Species Information for Protanthea simplex
Researched byAngus Jackson Data supplied byMarLIN
Refereed byDr Ib Svane
Scientific nameProtanthea simplex Common nameSealoch anemone
MCS CodeD668 Recent SynonymsNone

PhylumCnidaria Subphylum
SuperclassAnthozoa ClassHexacorallia
Subclass OrderActiniaria
SuborderProtantheae FamilyGonactiniidae
GenusProtanthea Speciessimplex

Additional InformationNo text entered
Taxonomy References Howson & Picton, 1997, Carlgren, 1921, Manuel, 1988,
General Biology
Growth formCylindrical
Feeding methodPassive suspension feeder
Mobility/MovementTemporary attachment
Environmental positionEpifaunal
Typical food typesInsufficient information HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityFragile SizeSmall(1-2cm)
HeightUp to 2 cm Growth RateInsufficient information
Adult dispersal potentialInsufficient information DependencyIndependent
General Biology Additional InformationThis species exhibits an unusual collapse behaviour, where at intervals, muscle tone is rapidly lost and the animals hangs limply from its disk attachment. This is considered to be an egestion process rather than a feeding, alarm or escape response. Despite the primitive musculature, Protanthea simplex is capable of active movement.
In Sweden Protanthea simplex has been recorded historically at densities of up to 2000 per square metre. Svane & Gröndal (1988) reported that the species was abundant below the algal belt in semi-sheltered and sheltered sites in the Gullmarsfjorden, Sweden (10.7 % and 4.5 % cover per 0.25 square metre respectively). This contrasted with earlier work by Gislén, undertaken between 1926-29, where the species was not recorded in the semi-sheltered sites and only made up a small proportion of the total wet weight of species in the sheltered sites (Svane & Gröndal, 1988).
Biology References McFarlane, 1985, Nyholm, 1959, Carlgren, 1893, Carlgren, 1921, Manuel, 1988, Svane & Groendahl, 1988,
Distribution and Habitat
Distribution in Britain & IrelandFrom the northern Firth of Clyde all along the west coast of Scotland, particularly in sea lochs. Not recorded in Orkney or Shetland. Recently (June 2006) found in Killary Harbour, Connemara.
Global distributionKillary Harbour (Connermara, Galway), Western Scotland out to Rockall Bank, round the coasts of the Skagerrak and northern Kattegat, Norway.
Biogeographic rangeNot researched Depth range9m to at least 500m
MigratoryNon-migratory / Resident   
Distribution Additional InformationNone entered

Substratum preferencesBedrock
Biogenic reef
Large to very large boulders
Small boulders
Physiographic preferencesStrait / sound
Offshore seabed
Biological zoneLower Infralittoral
Upper Circalittoral
Lower Circalittoral
Wave exposureSheltered
Very Sheltered
Extremely Sheltered
Ultra Sheltered
Tidal stream strength/Water flowWeak (<1 kn)
Very Weak (negligible)
SalinityFull (30-40 psu)
Variable (18-40 psu)
Habitat Preferences Additional InformationNone entered
Distribution References Nyholm, 1959, Carlgren, 1921, Manuel, 1988,
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismLecithotrophic
Reproductive SeasonSeptember to October Reproductive LocationWater column
Reproductive frequencyAnnual episodic Regeneration potential Yes
Life spanInsufficient information Age at reproductive maturityInsufficient information
Generation timeInsufficient information FecundityInsufficient information
Egg/propagule sizeInsufficient information Fertilization typeExternal
Larval/Juvenile dispersal potential>10km Larval settlement periodInsufficient information
Duration of larval stage11-30 days   
Reproduction Preferences Additional InformationAt 10-12 °C the larvae spend 15-20 days in the plankton before settling. In Sweden breeding occurs in September and October. Breeding terminates earlier in shallower water. Fertilization of the eggs occurs in the water column. The reproductive organs are white or orange- pink. Fragments of tissue in this species (except the tentacles) are capable of regenerating into complete anemones, a form of vegetative, asexual reproduction (Manuel, 1988).
Apart from Protanthea simplex, the only other species in the family Gonactinidae is Gonactinia prolifera. Gonactinia prolifera is unique in that the planula larva carries 'collar cells' similar in structure to the choanocyes of sponges and it is possible that Protanthea simplex has similar cells (I. Svane, pers. comm.). These secretory cells contain yolk granules and are undoubtedly involved in the formation of the fibrous coating of the planula which is again a unique feature of its planula (Chia et al, 1989).
Reproduction References Nyholm, 1959, Carlgren, 1921, Chia et al., 1989,
About MarLIN | Contact, Enquiries & Feedback | Terms & Conditions | Funding | Glossary | Accessibility | Privacy | Sponsorship

Creative Commons License BIOTIC (Biological Traits Information Catalogue) by MarLIN (Marine Life Information Network) is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License. Permissions beyond the scope of this license are available at Note that images and other media featured on this page are each governed by their own terms and conditions and they may or may not be available for reuse. Based on a work at