Description: Thallus up to 20 cms long, tubular to 6 mm broad composed of cells in longitual rows and loosely connected laterally, gelatinous.

Habitat: Rocks, woodwork, sea walls in the mid and upper littoral especially where there is fresh water.

Distribution: Widespread around the British Isles including the Shetlands. Europe: Mediterranean, Spain, France, Netherlands, Baltic, Norway, Sweden, Faroes and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, Long Island and New Jersey. Further afield: Japan.

Similar Species: Enteromorpha but with different cell arrangement. Microscopic examination required for identification.

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

iNaturalist: Capsosiphon fulvescens at iNaturalist World Species Observations database.

WoRMS: Capsosiphon fulvescens at World Register of Marine Species. Accepted name: Capsosiphon fulvescens (C.Agardh) Setchell & N.L.Gardner, 1920. AphiaID: 145935.

Classification: Biota; Plantae; Viridiplantae; Chlorophyta; Chlorophytina; Ulvophyceae; Ulotrichales; Ulotrichaceae; Capsosiphon