Description: Growing from a small crust to a well branched gelatinous frond up to 12 cms long and 2 mm broad. Fine filaments grow out in whorls of four and branch repeatedly, they are short and embedded in mucilage forming the outer surface of the branches.

Habitat: Very rare, on stones and shells in the sublittoral to 15 m.

Distribution: In the British Isles known only from a few sites: Cornwall, Devon, Pembroke, the Isle of Man and the Channel Isles. Europe: the Mediterranean, France and Spain. Further afield: Canary Islands and Tangier to Syria.

Similar Species: Schmitzia neapolitana (Berth.) Lagerh.

Key Identification Features:

• Soft and lubricous, apparently banded due to the whorls of branches.

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

iNaturalist: Calosiphonia vermicularis at iNaturalist World Species Observations database.

WoRMS: Calosiphonia vermicularis at World Register of Marine Species.