Species of "Fucus" are recorded almost worldwide. The name "fucus" appears in a number of taxa. "Fucus ceranoides" is a species similar to other species of "Fucus". It may typically overlap in distribution with "Fucus vesiculosus" and "Fucus serratus". "Fucus spiralis" is olive brown in colour and similar to "Fucus vesiculosus" and "Fucus serratus". The life cycle of "Laminaria" has heteromorphic alternation of generations which differs from "Fucus". It is sometimes abundant and forms a distinct zone just below the "Fucus serratus" zone. Pharmacologists are studying the medical effects of "Fucus coccineus melitensis" today. The modern distribution of "Fucus ceranoides" ranges from Portugal to Norway and Iceland. "F. serratus", toothed wrack, is the most distinctive of all the "Fucus" species. "Fucus spiralis" has spirally twisted fronds. "Fucus vesiculosus" is sold as a nutritional supplement. "Fucus ceranoides" is restricted to estuarine intertidal habitats under fluctuating salinities.