Astrorhiza limicola
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Astrorhiza limicola |
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| Scientific name | ||||||||||||
| Astrorhiza limicola | ||||||||||||
| Sandahl , 1858 |
Astrorhiza limicola is a kind of shell-bearing unicellular organism from the group of foraminifera .
features
The housing consists of only one chamber, which is lens-like, biconvex and star-shaped when viewed from above, the indentations between the arms are rounded. With a diameter of around 1 centimeter, they can become exceptionally large. At the end of each tube-like hollow arm there are openings for the pseudopod to exit .
The housing is agglutinated, i.e. composed of pieces of sediment that the animal ingests. The basis for this is a tectin secretion from the animal, which holds the particles together like an adhesive. There is no selection, the shells are always the same as the sediment in terms of their composition, the individual particles are between 30 and 1000 micrometers in size . The secretion is re-secreted even if the housing is damaged over a large area, with the animal in the meantime forming a fine membrane on the protoplasm for temporary protection of the interior.
Way of life
The animals are proven at sea depths of 12 to 3200 meters. They live standing on their side in fine sand, some of their arms are stuck in the sediment, the pseudopods emerging from them stand at depths of 2 to 3 millimeters and anchor the animal in the ground. False feet also protrude from the other arms of the shell, they can reach lengths of 6 to 7 centimeters and switch between two states: while they serve as tentacles, they can be sticky and thus hold their muzzle. The power of their pseudo-feet is great enough that they not only collect nutrient particles in the form of a (passive) filter , but also, for example, diatoms in the laboratory and live animals up to 3 centimeters in size, such as B. could catch and digest crabs ( Diastylis laevis , Caprellida , Artemia ). However, the animals were not actively killed, but died of exhaustion.
Astrorhiza limicola are not sessile, they can change their location, and speeds of around 25 centimeters in 24 hours have been repeatedly observed. Astrorhiza limicola can tolerate temporary lack of oxygen (up to 10 days).
Systematics
Astrorhiza limicola is the type species of the genus and was first described in 1857 by Oskar Teodor Sandahl based on specimens from the Skagerrak . In addition to the nominate form, Stschedrina Astrorhiza arenifera was placed as a variety under the species Astrorhiza limicola in 1979 .
proof
The information in this article is taken from the literature given under references; the following literature is also cited:
- ↑ a b Susan T. Goldstein: Foraminifera: A Biological Overview In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 40 .
- ↑ a b c d J.B. Buchanan, AH Hedley: A Contribution To The Biology Of Astrorhiza limicola (Foraminifera). In: Journal of the Marine Biological Association of the United Kingdom, 39 (3), pp. 549-560, 1960, online ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ Joan M. Bernhard, Barun K. Sen Gupta: Foraminifera of oxygen-depleted environments In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 208 .
Web links
- Photos of an enclosure on foraminifera.eu, online