Spiny wrack
| Spiny wrack | ||||||||||||
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Spike wrack ( Desmarestia aculeata ) |
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| Scientific name | ||||||||||||
| Desmarestia aculeata | ||||||||||||
| ( L. ) JV Lamouroux |
The spiny wrack ( Desmarestia aculeata ) is a type of brown algae from the order of the Desmarestiales . Widespread in the North Atlantic and North Pacific, it is also found in the North Sea and Baltic Sea. It only has its prickly appearance in summer and autumn.
description
The spiny kelp is a perennial seaweed that is initially light green-brown, later dark to black-brown in color. It is anchored to the ground with a small, compact adhesive disc. The upright, leathery-cartilaginous, sparsely branched thallus reaches a length of 50 to 100 cm (rarely up to 200 cm). The coarse, rod-shaped main axes are round at the base and 2 to 3 mm thick and slightly flattened further up. They usually have alternate side branches up to the second or third order. The outermost side branches are short and prickly and less than 1 mm thick.
These prickly twigs are only present in summer and autumn; in winter and spring the seaweed presents a completely different picture. Usually only the main axes hibernate, as the side branches are lost. From mid-February onwards, new branched long shoots grow out of the armpits and reach around 40 cm in length by the end of June. In spring these have dense tufts of yellow-brown-greenish, about 2 to 5 mm long, single-row and branched hair. Only when these tufts of hair are shed in June does the seaweed earn its name spiny wrack.
The thallus consists of a barked central axis. In contrast to the laminarial tissue, there is no real tissue ( parenchyma ) .
development
The spiny wrack shows a generation change with two very different generations (similar to Laminaria ). The visible seaweed is the diploid sporophyte . In December, the sori with the sporangia form on it between the bark cells , from which the zoospores are released after meiosis . These grow into microscopic male and female gametophytes . After the germ cells have formed and fertilized, the zygote develops into a new sporophyte.
Occurrence
The spiny wrack is widespread in the North Atlantic and North Pacific . In the north-east Atlantic it occurs from Greenland to Portugal, and also in the North Sea , Baltic Sea and the Mediterranean Sea (Spain, Corsica). In the Northwest Atlantic it grows from Labrador to New Jersey and in the North Pacific from Alaska to Oregon, in the Bering Sea and to Kamchatka. It was also found in the sub-Antarctic .
It inhabits shaded tidal pools in the lower tidal zone (Eulitoral) and the sublittoral below the low water line to depths of about 15 m. In the cloudy North Sea near Helgoland it occurs to a depth of about 10 m.
Systematics
The first description of the barbed wrack was in 1763 by Carl von Linné under the name Fucus aculeatus (in: Species plantarum 2, p. 1632). Jean Vincent Félix Lamouroux placed the species in the genus Desmarestia in 1813 (in: Essai sur les genres de la famille des thalassiophytes non articulées. Annales du Muséum d'Histoire Naturelle , Paris 20, p. 25). This is the type species of the genus Desmarestia .
Synonyms for Desmarestia aculeata (L.) JVLamouroux are Desmia aculeata (L.) Lyngbye, Ectocarpus densus Lyngbye, Fucus aculeatus L., Fucus muscoides Hudson, Fucus virgatus Gunnerus, Sphaerococcus aculeatus (L.) Stackhouse and Sporochnus L. .Agardh.
Desmarestia aculeata belongs to the Desmarestiaceae family within the order of the Desmarestiales .
swell
- Wolfram Braune: marine algae. A color guide to the common benthic green, brown and red algae of the world's oceans . Ruggell: Gantner, 2008, ISBN 978-3-906166-69-8 , pp. 172-173. (Sections Description, Occurrence)
- Michael D. Guiry, GM Guiry: Desmarestia aculeata - In: Algaebase - World-wide electronic publication, National University of Ireland, Galway , accessed April 22, 2012 (sections systematics, occurrence)
- P. Kornmann, PH Sahling: Sea algae from Helgoland - Benthic green, brown and red algae. Biological Institute Helgoland, Hamburg 1983, ISSN 0017-9957 , pp. 140-141. (Sections Description, Development)
