Furcellaria lumbricalis has a round and regularly
branched, 1-1,5 dm tall twin amongst the fork-formed red algae (Polyides
rotundus), that also blackens when it dries. When living or wet it is
somewhat more red in colour than furcellaria lumbricalis, which is
apparent when illuminated. The shoots are more fleshy and the crutch between
the branching is rounder compared to furcellaria lumbricalis and
when dried, the shoots are much easier to break off. Another characteristic
that is evident is when it is torn loose. Furcellaria lumbricalis
keeps its branching rootlets, while polyides rotundus is broken from
its disc-like holdfast. Polyides rotundus is found in shallow water
down to 15m in Bohuslän on the Swedish west coast. While diving along Marine
walls and over gravel bottoms, occasional specimens are seen, but large
colonies have, as yet not been observed.
Furcellaria lumbricalis is one of the
few algae to have a genuine Swedish name - kräkel. Carl von Linné
heard the word on Gotland for a type of fertilizer and gave the name to
this alga. Furcellaria lumbricalis was used as late as the 1940´s
as a fertilizer, the seaweed was washed up onto the beaches of Gotland and
Öland where it was piled into heaps and later transported to the fields.
Furcellaria lumbricalis is an agar-alga and therefore a potential
natural resource. Kolderup Rosenvinge stated that large quantities of loose
furcellaria lumbricalis were to found in the Kattegatt, e.g. on Anholt.
For a period, Denmark was able to sustain an agar- industry because of the
large quantities found in Danish waters. Because of over consumption / production,
these resources have since became depleted.
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