Description: Fairly stiffly branched fronds growing from a discoid holdfast, covered with small branchlets arranged in whorls. Maximum length usually about 15 cms.

Habitat: Common. Mainly epilithic in rock pools of the mid-littoral to upper sublittoral.

Distribution: Widespread around the British Isles from the Shetlands to the Channel Islands. Europe: Azores, Portugal, Atlantic coasts of Spain and France, Baltic Sea, Norway, Faroes and Iceland. Atlantic coast of North America: New Hampshire, Massachusetts, Rhode Island, Connecticut and Loong Island. Further afield: west coast of Greenland in Baffin Bay, Canary Islands, Australia and Tasmania.

Key Identification Features:

• Whorls of branchlets very close together in forma spongiosus, close but distinct in forma verticillatus.

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

iNaturalist: Cladostephus spongiosus at iNaturalist World Species Observations database.

WoRMS: Cladostephus spongiosus at World Register of Marine Species. Accepted name: Cladostephus spongiosus (Hudson) C.Agardh, 1817. AphiaID: 145888.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Dictyotophycidae; Sphacelariales; Cladostephaceae; Cladostephus