Cassiopea andromeda
| Cassiopea andromeda | ||||||||||||
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Cassiopea andromeda |
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| ( Forsskål , 1775) |
Cassiopea andromeda is a species of jellyfish. Atypical for jellyfish, it lives mostly sedentary on the flat seabed, with the underside turned up.
description
Medusa
The jellyfish has a yellow-brown colored, smooth, plate-like umbrella without edge tentacles with an almost smooth edge, roughly the shape of a suction cup, when fully grown with a diameter of about 300 millimeters. It can have white marks made up of spots and radial stripes, but this is variable, often washed out and can also be completely missing. The central mouth opening is surrounded by eight pinnately finely branched mouth arms, the length of which does not quite reach the umbrella diameter. The mouth arms branch out in two parts (dichotomous), sometimes several from one root (tree-shaped or palm-shaped, pinnat), very fine on the outside. All arm branches are spread out in one plane, striving away from the screen at an acute angle. At the end they have flat, hem-like outgrowths. As is typical of medusa, they are densely covered with nettle capsules. On the arms sit vertically protruding, differently colored so-called piston bubbles of different numbers and sizes, which presumably have a sensory function. The color of the arms of the mouth is very variable.
The inside of the mouth is adjoined by a lenticular stomach cavity with a very small diameter in relation to the size of the umbrella. This continues to the outside in approx. 32 radially running channels, which are connected to one another by a network of cross connections (anastomoses), which run through the entire body including the arms.
The underside of the jellyfish, especially the mouth arms, has embedded symbiotic autotrophic (i.e. photosynthesis- capable) dinoflagellates that are assigned to different strains of the species Symbiodinium microadriaticum (the color of the jellyfish is not related to these and their special color). Such so-called zooxanthellae are otherwise more typical of polyps in cnidarians, especially coral species. In Cassiopea , too , they occur both in the polyp and in the medusa stage. The jellyfish depends on its endosymbionts and cannot survive without them. It does not feed purely autotrophically, but also predatory, especially planktonic small crustaceans (especially copepods ).
polyp
The polyp stage of the species is 5 to 10 millimeters in size, long-stalked with a bowl-shaped calyx (calyx). The foot and the stem are protected by a solid periderm tube up to about half their length. A cylindrical, four-lipped hypostome sits on the somewhat sunk mouth disc, and around 40 thin tentacles on the edge of the calyx. The polyp carries the same symbiotic zooxanthellae as the medusa stage.
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Life cycle
The species has the typical generation change ( metagenesis ) of most cnidarians. The segregated, rarely also hermaphrodite medusas produce planula larvae that attach to hard substrate on the sea floor and form the generation of polyps. For example, fallen mangrove leaves are used as a substrate, but they can also be found on a variety of other things, from dead seaweed to plastic waste. Polyps tie up their head part by strobilation to form freely swimming medusa larvae, called ephyries, which grow into medusa, alternatively they can also secrete bud-like germs from daughter polyps. These are motile like larvae and only differentiate after removal from the mother polyp. During strobilation, each polyp constricts a single, less than 4 millimeter wide ephyria (monodisc development), leaving only the stalk section with a new mouth opening, which then regenerates by forming the calyx. The Ephyre consists of a flat umbrella with numerous small edge lobes with rounded tips, which are connected in pairs by a membrane. A long mouth stalk (manubrium) sits in the center.
Ecology and way of life
The adult medusas usually lie on the bottom of the sea so that the umbrella is against the bottom with the mouth stalks up. Since the screen is not initially visible, they resemble a sea anemone when viewed superficially. With weak undulating wave movements, the umbrella pumps water towards the mouth stalks, which are fed by planktonic prey organisms. If necessary, she can swim. Since the species mainly feeds on its autotrophic endosymbionts, it prefers shallow, well-lit water depths, including the tidal zones . The medusas only occur on a fine sandy or muddy substrate. The species lives mainly in tropical waters, but can penetrate into warm sea zones such as the Mediterranean Sea. It likes to live, but by no means exclusively, in mangroves , which is why it is sometimes referred to as "mangrove jellyfish". In an investigation in the Red Sea, the species was assessed as a key ecological species on the seabed there. They preferred the transition zone between a coral reef and the adjoining sandbank over these habitats themselves; it was least common in seagrass meadows. The density in the transition zone was about eight individuals per square meter, which (in the reef zone) covered up to a maximum of about 20 percent of the ground.
The species lives in symbiosis with cleaner shrimp of the genus Periclimenes (family Palaemonidae ) and Idiomysis tsunrnamali (family Mysidae ). Per medusa there are usually one to four of the transparent shrimp, details of the relationship are so far hardly known.
Poisonous effect
Like many jellyfish, Cassiopea andromeda has a nettle poison that also affects humans. It can cause painful stitches on sensitive, unprotected skin.
Systematics and taxonomy
The species was first described by Peter Forsskål in 1775 as Medusa andromeda and in 1829 transferred by Johann Friedrich Eschscholtz to the newly described genus Cassiopea . The taxonomy of the genus on a morphological basis is characterized by confusion and disagreements between different authors. While at the beginning almost every processor described his material from a new region as a new species or at least a new subspecies, mostly on the basis of slight modifications of color and shape, all these forms were later combined into the broad collective species Cassiopea andromeda . According to this concept, the genus contained only one species (monotypical). Mostly, however, at least the forms from the Caribbean were recognized as separate species Cassiopea xamachana and C. frondosa . According to more recent DNA studies, morphological differences in the genus are too variable to be able to differentiate between species with certainty. With the help of the mtDNA , six clearly divergent groups with substantial genetic differences could be distinguished, which in the opinion of the authors deserve species rank. The Caribbean Cassiopea xamachana and the Indo-Pacific widespread Cassiopea andromeda turned out to belong to the same clade , so that, according to the results, a species difference between them would not be justified. However, the authors have the cryptic species indeed distinguished, but not formally described and named so that the now differentiated morphologically indistinguishable cryptic species complex sometimes do not have a valid species names.
distribution
While the collective species Cassiopea andromeda is distributed almost worldwide, the species in the narrower sense (cf.) is distributed in the Pacific, Indian Ocean and the Red Sea. After the Suez Canal was built, she immigrated to the Mediterranean (an example of the so-called Lesseps migration ). In the canal itself, the first evidence comes from 1886, the first discovery was made in the Mediterranean Sea (near Cyprus) in 1903, later discoveries in 1955 near Santorini and 1990 on the Israeli coast, and since 2008 also in a lagoon on the Turkish coast. In the meantime this species has also been discovered as a neobiont in the western Mediterranean off the coast of Malta . There are also finds from Hawaii, near the port of Pearl Harbor , which belong to various of the crypto species, including C. andromeda in the narrower sense. Here, a spread through ship growth or ballast water is obvious, which probably also contribute to the spread of the species in other ways.
swell
- Gustav Stiasny (1921): Studies on rhizostomes with special consideration of the fauna of the Malay Archipelago together with a revision of the system. Capita zoologica deel I, aflevering 2: 1-178. Full text source
Web links
Individual evidence
- ^ Rudolf J. Blank & Volker AR Huss (1989): DNA divergency and speciation in Symbiodinium (Dinophyceae). Plant Systematics and Evolution Volume 163, Issue 3-4: 153-163.
- ^ Lampert, KP, Bürger, P., Striewski, S. and Tollrian, R. (2012): Lack of association between color morphs of the Jellyfish Cassiopea andromeda and zooxanthella clade. Marine Ecology 33: 364-369. doi : 10.1111 / j.1439-0485.2011.00488.x
- ↑ a b Ilka Straehler-Pohl (2009): The phylogeny of the Rhopaliophora (Scyphozoa and Cubozoa) and the paraphyly of the 'Rhizostomeae'. Dissertation, University of Hamburg.
- ↑ DK Hofmann, WK Fitt, J. Fleck (1996): Checkpoints in the life-cycle of Cassiopea spp .: control of metagenesis and metamorphosis in a tropical jellyfish. International Journal of Developmental Biology 40: 331-338.
- ↑ Wolfgang Niggl & Christian Wild (2010): Spatial distribution of the upside-down jellyfish Cassiopea sp. within fringing coral reef environments of the Northern Red Sea - implications for its life cycle. Helgoland Marine Research Volume 64, Issue 4: 281-287.
- Jump up ↑ JE Martinelli Filho, SN Stampar, AC Morandini, EC Mossolin (2008): Cleaner shrimp (Caridea: Palaemonidae) associated with scyphozoan jellyfish. Vie et milieu - life and environment 58 (2): 133-140.
- ^ Gian Luigi Mariottini & Luigi Pane (2010): Mediterranean Jellyfish Venoms: A Review on Scyphomedusae . In: Marine Drugs 8: 1122-1152. doi : 10.3390 / md8041122
- ↑ Mustafa Alparslan Poisonous Marine Organisms In Turkey And First Medical Aids. In: 2nd International Symposium on Sustainable Development, June 8-9 2010, Sarajevo. download
- ↑ a b c Brenden S. Holland, Michael N. Dawson, Gerald L. Crow, Dietrich K. Hofmann (2004): Global phylogeography of Cassiopea (Scyphozoa: Rhizostomeae): molecular evidence for cryptic species and multiple invasions of the Hawaiian Islands. Marine Biology 145: 1119-1128. doi : 10.1007 / s00227-004-1409-4
- ^ BS Galil, E. Spanier, WW Ferguson (1990): The Scyphomedusae of the Mediterranean coast of Israel, including two Lessepsian migrants new to the Mediterranean. Zoological Mededelingen 64: 95-105.
- ↑ Elif Özgür & Bayram Öztürk (2008): A population of the alien jellyfish, Cassiopea andromeda (Forsskål, 1775) (Cnidaria: Scyphozoa: Rhizostomea) in the Ölüdeniz Lagoon, Turkey. Aquatic Invasions Volume 3, Issue 4: 423-428. doi : 10.3391 / ai.2008.3.4.8
- ↑ Patrick J. Schembri et al. (2009): First record of Cassiopea andromeda (Scyphozoa: Rhizostomeae: Cassiopeidae) from the central Mediterranean Sea (PDF; 105 kB) , Marine Biodiversity Records
- ^ Bishop Museum and University of Hawaii: Guidebook of Introduced Marine Species of Hawaii