Description: Thallus filamentous well branched and tufted to 20 cms long, bluish-green in colour and firm in texture. Attached by rhizoids. Filaments straight or a little curved.

Habitat: Common. In rock pools of the mid to lower littoral and upper sublittoral. Has been recorded from brackish waters.

Distribution: Widespread in the British Isles. Europe: Mediterranean, Portugal, Atlantic coast of Spain and France, Netherlands, Baltic Sea, Sweden, Gulf of Finland, Norway, Faroes, Jan Mayen and Bjornoya and Iceland. Atlantic coast of North America: Canada, Maine, New Hampshire and Massachusetts. Further afield: Murman Sea, Novaya Zemlya, White Sea and the west coast of Greenland.

Similar Species: Many species of Cladophora are similar and difficult to identify.

Key Identification Features:

• Firm texture and bluish green colour.

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

iNaturalist: Cladophora rupestris at iNaturalist World Species Observations database.

WoRMS: Cladophora rupestris at World Register of Marine Species.