Chorda filum

Researched ByNicola WhiteData Supplied ByMarLIN
Refereed byDr Stefan Kraan
Taxonomy
Scientific nameChorda filumCommon nameSea lace or Dead man's rope
MCS CodeZR345Recent SynonymsChorda filum var thrix
PhylumChromophycotaSubphylum
SuperclassClassPhaeophyceae
SubclassOrderLaminariales
SuborderFamilyChordaceae
GenusChordaSpeciesfilum
Subspecies  
Additional InformationOther common names include mermaid's tresses and cat gut.
Taxonomy References South & Burrows, 1967, Guiry & Nic Dhonncha, 2002
General Biology
Growth formFiliformFeeding methodPhotoautotroph
Mobility/MovementPermanent attachmentEnvironmental positionEpifloral
Typical food typesNot relevantHabitAttached
BioturbatorNot relevantFlexibilityHigh (>45 degrees)
FragilityIntermediateSizeLarge(>50cm)
HeightGrowth Rate17 cm/month
Adult dispersal potentialNoneDependencyIndependent
SociabilitySolitary
Toxic/Poisonous?No
Additional InformationChorda filum is a summer annual, falling into decay in the autumn and disappearing during winter. Growth rate is maximal during the summer. The adult frond is a hollow tube, the walls of which are spirally constructed. The frond is frequently inflated with gases in the terminal region. Plants usually grow in clumps. The end of the frond decays continuously and is replaced by growth from a sub-terminal meristem. Hairs are sparse or absent on older plants.
Biology References South & Burrows, 1967
Distribution and Habitat
Distribution in Britain & IrelandAll coasts of Britain and Ireland, but rarer in south east England.
Global distributionSee additional information.
Biogeographic rangeNot researchedDepth rangeRock pools down to 5m.
MigratoryNon-migratory / Resident
Distribution Additional InformationGlobal distribution
Canada (Arctic), Alaska, NW Atlantic from Labrador to New Jersey, Greenland, Iceland, Spitsbergen, Norway, Sweden, Denmark, The Netherlands, Belgium, the Baltic, the Faroes, France, Spain, Portugal, Canary Islands, Greece, China, Japan and south Kurile Islands, NE Pacific and the Bering Strait.

Chorda filum occurs in sheltered bays, estuaries, lagoons and sea lochs. It is rarely found on the open coast and is completely absent from exposed shores. The plants occur in clumps on a range of unstable, small objects such as pebbles and shells. It may also be found on sand and detritus but it will not remain for long on this substratum (S. Kraan, pers. comm.). They are also epiphytic on %Zostera marina% and %Fucus vesiculosus%. During stormy weather, plants may be washed to more sheltered locations where they continue development. Chorda filum has considerable tolerance to reduced salinities and extends into river mouths and the Baltic, where it grows at 3.5 psu. However, plants that grow in fully marine conditions cannot withstand immersion in freshwater for 2 hours (Russell, 1985).

Substratum preferencesMuddy gravel, Pebbles, Gravel / shingle, Mixed, AlgaePhysiographic preferencesStrait / sound, Sealoch, Ria / Voe, Estuary, Isolated saline water (Lagoon), Enclosed coast / Embayment
Biological zoneLower Infralittoral, Upper Infralittoral, Sublittoral FringeWave exposureSheltered, Very Sheltered
Tidal stream strength/Water flowModerately Strong (1-3 kn), Weak (<1 kn)SalinityLow (<18 psu), Reduced (18-30 psu), Full (30-40 psu), Variable (18-40 psu)
Habitat Additional Information
Distribution References South & Burrows, 1967, Russell, 1985, Norton & South, 1969, Hardy & Guiry, 2003
Reproduction/Life History
Reproductive typeAlternation of generations Developmental mechanismSpores (sexual / asexual)
Reproductive SeasonSporophytes appear on shore Feb-MarchReproductive LocationAs adult
Reproductive frequencyAnnual protracted Regeneration potentialNo
Life spanInsufficient informationAge at reproductive maturity<1 year
Generation time<1 yearFecundityMillions of spores
Egg/propagule sizeFertilization type
Larvae/Juveniles
Larval/Juvenile dispersal potential100-1000mLarval settlement periodNot relevant
Duration of larval stageNot relevant  
Additional InformationChorda filum has a similar life-history to other Laminariales, exhibiting alternation of heteromorphic generations. The species has a macroscopic diploid sporophyte and a microscopic haploid gametophyte. The gametophytes consist of clumps of prostate, branched, filaments approximately 100 micrometres long. Female gametophytes are less branched than male ones and may be distinguished by their larger more densely pigmented cells. The male gametophytes are smaller, paler in colour and more densely branched than the females. Chorda filum exhibits a protracted reproductive period. Visible sporophytes appear on shores between February and mid-March and develop into secondary sporophytes between April and June. The sporophytes are washed away from October to February, leaving behind zoospores or gametophytes. The size of plants is not related to their state of maturity, although the smallest plants to bear sporangia have been observed to be 36.6 cm long. When the meristem becomes indistinct it is likely that fruiting has begun. During the period of fertility the whole plant except the lowermost 5-10 cm, is covered in unilocular sporangia. Experiments on growing Chorda filum in culture have shown that fruiting appears to be endogenously controlled and occurs irrespective of environmental conditions (South & Burrows, 1967).
Reproduction References South & Burrows, 1967, Fredriksen et al., 1998