Dictyota dichotoma (Hudson) Lamouroux

Description: Thallus flat with fairly regular dichotomous branches with parallel sides to 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 BioMar data for Ireland - Google Earth map:  download this placemark (not got Google Earth installed?)

Distribution Map from NBN: JNCC MNCR Seasearch data - Grid map : Interactive map : National Biodiversity Network mapping facility, data for UK.