BIOTIC Species Information for Chorda filum
Researched byNicola White Data supplied byMarLIN
Refereed byDr Stefan Kraan
Scientific nameChorda filum Common nameSea lace or Dead man's rope
MCS CodeZR345 Recent SynonymsChorda filum var thrix

PhylumChromophycota Subphylum
Superclass ClassPhaeophyceae
Subclass OrderLaminariales
Suborder FamilyChordaceae
GenusChorda Speciesfilum

Additional InformationOther common names include mermaid's tresses and cat gut.
Taxonomy References South & Burrows, 1967, Guiry & Nic Dhonncha, 2002,
General Biology
Growth formFiliform
Feeding methodPhotoautotroph
Mobility/MovementPermanent attachment
Environmental positionEpifloral
Typical food typesNot relevant HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityIntermediate SizeLarge(>50cm)
Height Growth Rate17 cm/month
Adult dispersal potentialNone DependencyIndependent
General Biology 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 researched Depth 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
Gravel / shingle
Physiographic preferencesStrait / sound
Ria / Voe
Isolated saline water (Lagoon)
Enclosed coast / Embayment
Biological zoneLower Infralittoral
Upper Infralittoral
Sublittoral Fringe
Wave 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 Preferences 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-March Reproductive LocationAs adult
Reproductive frequencyAnnual protracted Regeneration potential No
Life spanInsufficient information Age at reproductive maturity<1 year
Generation time<1 year FecundityMillions of spores
Egg/propagule size Fertilization type
Larval/Juvenile dispersal potential100-1000m Larval settlement periodNot relevant
Duration of larval stageNot relevant   
Reproduction Preferences 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,
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