Description: Thallus flat with fairly regular dichotomous branches with parallel sides to a 30 cms long the tips usually bifid. Outer layer of small cells enclosing a single layer of large cells no more than one cell thick even near the base. Branches 3 to 12 mm wide, membranous without a mid-rib.

Habitat: Common, in places abundant. Littoral rock pools and sublittoral.

Distribution: Throughout the British Isles from the Shetlands to the Channel Islands, though less common on the eastern shores of England. Europe: Mediterranean, Azores, Portugal, Atlantic coasts of Spain and France, Baltic Sea and Norway. Atlantic coast of North America: Virginia. Further afield: Jamaica, Salvage Islands, Canary Islands, Mauritania to South Africa, Mauritius, Australia and Tasmania, Japan and Phillipine Islands.

Similar Species: Dictyota spiralis; Cutleria multifida.

Key Identification Features:

• Flat with regular dichotomous branches. D.spiralis has a central tissue of large cells more than one cell thick in the lower parts of the thallus.

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

iNaturalist: Dictyota dichotoma at iNaturalist World Species Observations database.

WoRMS: Dictyota dichotoma at World Register of Marine Species. Accepted name: Dictyota dichotoma (Hudson) J.V.Lamouroux, 1809. AphiaID: 145367.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Dictyotophycidae; Dictyotales; Dictyotaceae; Dictyoteae; Dictyota