Dead sea hand
| Dead sea hand | ||||||||||||
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Dead sea hands in the Aquazoo - Löbbecke Museum in Düsseldorf |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Alcyonium digitatum | ||||||||||||
| Linnaeus , 1758 |
The Dead Sea Hand ( Alcyonium digitatum ), also known as Dead Man's Hand , Nordic Cork Coral or Bastard Sponge , is a leather coral (Alcyoniidae).
features
It is palm-shaped, sometimes lump-shaped and usually reaches a height of ten, less often 15 centimeters. The dead man's hand is white, yellowish, light orange or pink. It has small lime needles called sclerites in its body to strengthen it . Like almost all corals, it is an animal colony made up of many individual polyps . The interior of the colony is criss-crossed by a multitude of narrow, small channels through which the individual animals communicate with one another. The polyps, which have eight feathered tentacles , reach a size of one centimeter. In contrast to most of its relatives from tropical seas, it does not live in symbiosis with zooxanthellae and feeds exclusively on plankton catch. Since the shape and color of the Dead Sea Hand are reminiscent of a piece of a water corpse, it received its macabre German name (similar to English dead man's finger ).
distribution
The dead sea hand occurs in the North Sea , in the European Atlantic , in the English Channel and in the western Baltic Sea . In the Mediterranean the genus is represented by Alcyonium palmatum .
habitat
It lives at depths from 20 meters on rocky ground, mollusc shells , crab shells , sunken ship hulls, cans and bottles that have gone overboard, on pier walls and bridge piers; in the upper permanent flood zone and below.
General
If you observe them in an aquarium for a whole day, you can follow a steady rhythm with which the colony changes. In the active phase, the entire colony pumps itself full of water, and the small polyps protrude clearly above the surface in order to fish out small plankton organisms from the water. In the shrunken (resting) state, the individual animals are completely drawn in and only leave small warts on the surface. A colony is created by budding from a single individual. The animals are of separate sex. The gametes are released into the open water from the sex buds, which sit on the partition walls of the cavity, and are fertilized there. Small eyelash larvae develop from them , which change to soil life and grow into a new colony.
literature
- Rainer Kaiser: Lower animals of tropical and cold seas in the aquarium . Ulmer, Stuttgart 1991, ISBN 3-8001-7222-4
- Josef H. Reichholf : Mollusks and other invertebrates.
