Description: Filamentous, growing to 20 cms long with a well-marked central axis, becoming hollow below, sparingly branched.

Habitat: Not uncommon. Epilithic in the littoral and epizoic on mussel shells.

Distribution: British Isles, mainly northern in distribution, however recorded from south Wales, Northern Ireland and Scotland. Europe: France, Baltic Sea, Norway, Faroes, Spitzbergen and Iceland. Greenland. Atlantic coast of North America: Canada and Rhode Island. Further afield: Black Sea and Japan.

Distribution Map from NBN: Dictyosiphon chordaria at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Dictyosiphon chordaria at iNaturalist World Species Observations database.

WoRMS: Dictyosiphon chordaria at World Register of Marine Species.