Himanthalia elongata

Scientific classification

(unranked):     SAR

Superphylum: Heterokonta

Class:   Phaeophyceae

Order: Fucales

Family:            Himanthaliaceae

Genus: Himanthalia

Species:           H. elongata

Binomial name           Himanthalia elongata

(Linnaeus) S.F. Gray [1]

Synonyms

Fucus elongatus Linnaeus, 1753

Fucus loreus Linnaeus, 1767

Fucus pruniformis Gunnerus, 1772

Fucus tomentosus Hudson, 1778

Funicularius tuberculatus Roussel, 1806

Himanthalia lorea (Linnaeus) Lyngbye, 1819

Himanthalia elongata is a brown alga in the order Fucales, also known by the common names thongweed, sea thong and sea spaghetti. It is found in the north east Atlantic Ocean and the North Sea.

According to the World Register of Marine Species, Himanthalia elongata is the only member of its genus, Himanthalia Lyngbye, 1819 and the only member of its family, Himanthaliaceae (Kjellman) De Toni, 1891.

H. elongata is a common brown alga of the lower shore. The thallus is at first a small flattened or saucer-shaped disc up to three centimetres wide with a short stalk.

In the autumn or winter, long thongs grows from the centre of this, branching dichotomously a number of times. They grow fast and can reach up to two metres by the following summer when they become mature.

They bear the conceptacles, the reproductive organs, and begin to decay when the gametes have been released into the water. The discs live for two or three years.

H. elongata is found in the Baltic Sea, the North Sea and the north east Atlantic Ocean from Scandinavia south to Portugal. It is found on gently shelving rocky shores in the lower littoral zone and the sublittoral zone particularly on shores with moderate wave exposure. It is sometimes abundant and forms a distinct zone just below the Fucus serratus zone.