BIOTIC Species Information for Chorda filum
Researched byNicola White Data supplied byMarLIN
Refereed byDr Stefan Kraan
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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