Hose scabbard
| Hose scabbard | ||||||||||||
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Tube scabbard ( Ciona intestinalis ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Ciona intestinalis | ||||||||||||
| Linnæus , 1767 |
The Ciona intestinalis ( Ciona intestinalis ), also Schlauchascidie called, is a sessile tunicate (tunicates), which is common in the eastern Atlantic and North Pacific. It also lives in the Mediterranean , on the European Atlantic coasts, in the North Sea and in the western Baltic Sea and grows on rocks, algae, mussel shells and jetties from the mean tidal low water (MTNW) to depths of 500 meters.
features
The tubular sea squirt lives solitary or in loose groups, so it does not form animal hives from many individual individuals like many other sea squirts. Your slender, upright body grows to a maximum height of eight inches, but in most cases remains significantly lower.
Their color is milky-whitish, pale yellow or greenish and almost translucent. The edge of the outflow opening is yellow, the reddish intestines shine through.
development
The tubular sea squirts are simultaneous hermaphrodites , i. H. Eggs and sperm are produced almost simultaneously by the gonads of a sexually mature animal. Eggs are only released into the water when a chemical sensory organ signals the presence of sperm from other tubular sea squirts. This will avoid self-fertilization . The larvae hatch about 25 hours after fertilization.
The larvae of the tubular sea squirt are free-living. With the help of a muscular oar tail and a rod-shaped, elastic support along the back, the chorda dorsalis , the sea squirt larvae can move easily within the plankton . They have a brain vesicle that is connected to a neural tube . In vertebrates , the spine develops from the notochord and the neural tube . In the sea squirts, however, these systems are regressed in the sessile stage.
After about 36 hours of life within the marine plankton, the larva settles on hard ground with the help of an adhesive papilla in the throat region. The notochord, which consists of cells containing nutrients, is reabsorbed. The neural tube and the cerebral vesicle disappear, after their regression there is only one ganglion .
nutrition
The stuck tubular sea squirts feed as filter feeders . A stream of water is generated with the help of cilia that line the gill intestine. This is conducted over the fine epithelia of the gill slit, which is covered with a network of sticky secretions. This is where the usable food particles stick and are drawn into the midgut along with the net and finally digested. The slime web is constantly being replicated. The filtered water is fed directly into the atrium, a cavity formed by the jacket, from where it is released to the outside again through the egestion opening . One can often observe the currents of clean, filtered water in the vicinity of the tubular sea squirts when they stand out clearly from polluted water, for example in a harbor basin. The rectum also opens into the atrium.
genetics
The tubular sea squirt serves as a model organism , both in developmental biology and in molecular genetics . She was one of the first animals whose genome was completely sequenced. At 160 million base pairs , it is relatively small, about one twentieth of the human genome. The 2002 publication was the first for a chordist . Around 16,000 genes on 14 pairs of chromosomes were located.
In further genetic investigations it turned out that the tubular sea squirt is a species complex consisting of at least two different species that hardly differ externally. On the basis of the genome, however, it was possible to differentiate between two species, which occur on the one hand in the Pacific and on the other in the European North Atlantic . The specimen sequenced in 2002 came from Half Moon Bay on the Pacific coast of California , a European comparison specimen from the west coast of Scotland . It is believed that the two groups have diverged for at least 20 million years. However, the morphological differences are small. Hybrids between the two groups could also be bred in the laboratory, but these are sterile. A 2010 study suggests a differentiation into two other species, one restricted to the Mediterranean Sea and the other restricted to the Black Sea . It is therefore assumed that the tubular sea squirt, which is widespread worldwide, is actually made up of four cryptic species .
Individual evidence
- ↑ Bernhard Grzimek (ed.): Grzimeks animal life. Encyclopedia of the Animal Kingdom in 13 volumes. Volume 3, Kindler, Zurich 1967–1972
- ^ N. Coleman: Encyclopedia of Marine Animals. Blandford, London 1991
- ^ Mieke Braune: Ciona intestinalis or the hose ascidia. Biology Student Council, Leibniz University Hannover , January 2005
- ↑ P. Dehal et al .: The draft genome of Ciona intestinalis: insights into chordate and vertebrate origins. Science, 298, 5601, pp. 2157-67, December 13, 2002
- ↑ Shoguchi et al .: Molecular Cytogenetic Characterization of Ciona intestinalis Chromosomes. Zoological Science, 22, 5, pp. 511-516, May 2005
- ↑ Miho M. Suzuki, Teruaki Nishikawa, Adrian Bird: Genomic approaches reveal unexpected genetic divergence within Ciona intestinalis. Journal of Molecular Evolution, 61, pp. 627-635, 2005
- ↑ Luigi Caputi, Nikos Andreakis, Francesco Mastrototaro, Paola Cirino, Mauro Vassillo, Paolo Sordino: Cryptic speciation in a model invertebrate chordate. Proceeding of the National Academy of Science of the United States of America, 104, pp. 9364-9369, May 29, 2007 doi : 10.1073 / pnas.0610158104
- ↑ Aibin Zhan, Hugh J. Macisaac, Melania E. Cristescu: Invasion genetics of the Ciona intestinalis species complex: from regional endemism to global homogeneity. Molecular Ecology, 19, pp. 4678-4694, 2010 doi : 10.1111 / j.1365-294X.2010.04837.x
literature
- Klaus Janke and Bruno P. Kremer: Dune, Beach and Wadden Sea. Animals and plants of our coasts. 2006, Franckh-Kosmos Verlag, ISBN 3-440-09576-2
- Erhardt / Moosleitner: Mergus Sea Water Atlas Volume 3 , Mergus-Verlag, Melle, 1997, ISBN 3-88244-103-8
Web links
- World Register of Marine Species, Shenkar, N .; Sanamyan, K .; Monniot, C. (2013): Ciona intestinalis (Linnaeus, 1767)