Scyphozoa
| Scyphozoa Временный диапазон:
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| Цефея Цефея | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Subphylum: | Medusozoa |
| Class: | Scyphozoa Götte, 1887 |
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Scyphozoa Cnidaria исключительно морской класс Phylum , - [ 2 ] называется истинной медузой (или «настоящие желе»).
Название класса Scyphozoa происходит от греческого слова Skyphos ( σκύφος ), обозначая своего рода чашку питья и ссылается на форму чашки организма. [ 3 ]
Сцифозоанцы существовали от самого раннего кембрия до настоящего. [ 1 ]
Биология
[ редактировать ]Большинство видов Scyphozoa имеют две фазы истории жизни, в том числе планктонную медузу или форму полипов , что наиболее очевидно в теплые летние месяцы, и незаметной, но долгоживущей полипов, который сезонно приводит к новым медузам. Полем Большинство крупных, часто красочных и заметных медуз, найденных в прибрежных водах по всему миру, - это Scyphozoa. [ 4 ] Они обычно варьируются от От 2 до 40 см (от 1 до 15 + 1 ⁄ 2 дюйма) в диаметре, но самый большой вид, Cyanea Capillata может достигать 2 метров (6 футов 7 дюймов) в течение. Scyphomedusae встречаются по всему мировому океанам, от поверхности до больших глубин; Никакой Scyphozoa не происходит в пресной воде (или на суше).
As medusae, they eat a variety of crustaceans and fish, which they capture using stinging cells called nematocysts. The nematocysts are located throughout the tentacles that radiate downward from the edge of the umbrella dome, and also cover the four or eight oral arms that hang down from the central mouth. Some species, however, are instead filter feeders, using their tentacles to strain plankton from the water.[5]
Anatomy
[edit]Scyphozoans usually display a four-part symmetry and have an internal gelatinous material called mesoglea, which provides the same structural integrity as a skeleton. The mesoglea includes mobile amoeboid cells originating from the epidermis.
Scyphozoans have no durable hard parts, including no head, no skeleton, and no specialized organs for respiration or excretion.[6][7] Marine jellyfish can consist of as much as 98% water, so are rarely found in fossil form.
Unlike the hydrozoan jellyfish, Hydromedusae, Scyphomedusae lack a vellum, which is a circular membrane beneath the umbrella that helps propel the (usually smaller) Hydromedusae through the water. However, a ring of muscle fibres is present within the mesoglea around the rim of the dome, and the jellyfish swims by alternately contracting and relaxing these muscles.[8] The periodic contracting and relaxing propels the jellyfish through the water, allowing it to escape predation or catch its prey.
The mouth opens into a central stomach, from which four interconnected diverticula radiate outwards. In many species, this is further elaborated by a system of radial canals, with or without an additional ring canal towards the edge of the dome. Some genera, such as Cassiopea, even have additional, smaller mouths in the oral arms. The lining of the digestive system includes further stinging nematocysts, along with cells that secrete digestive enzymes.[5]
The nervous system usually consists of a distributed net of cells, although some species possess more organised nerve rings. In species lacking nerve rings, the nerve cells are instead concentrated into small structures called rhopalia. There are between four and sixteen of these small lobes arranged around the rim of the umbrella, where they coordinate the muscular action allowing the animal to move. Each rhopalium is typically associated with a pair of sensory pits, a statocyst, and sometimes a pigment-cup ocellus.[5]
Reproduction
[edit]
1–3 Larva searches for site
4–8 Polyp grows
9–11 Polyp strobilates
12–14 Medusa grows
Most species appear to be gonochorists, with separate male and female individuals. The gonads are located in the stomach lining, and the mature gametes are expelled through the mouth. After fertilization, some species brood their young in pouches on the oral arms, but they are more commonly planktonic.[5]
Growth and development
[edit]The fertilized egg produces a planular larva which, in most species, quickly attaches itself to the sea bottom. The larva develops into the hydroid stage of the lifecycle, a tiny sessile polyp called a scyphistoma. The scyphistoma reproduces asexually, producing similar polyps by budding, and then either transforming into a medusa, or budding several medusae off from its upper surface via a process called strobilation. The medusae are initially microscopic and may take years to reach sexual maturity.[5]
Commercial importance
[edit]Scyphozoa include the moon jelly Aurelia aurita,[9] in the order Semaeostomeae, and the enormous Nemopilema nomurai, in the order Rhizostomeae, found between Japan and China and which in some years causes major fisheries disruptions.
The jellyfish fished commercially for food are Scyphomedusae in the order Rhizostomeae.[10] Most rhizostome jellyfish live in warm water.[4]
Taxonomy
[edit]Although the Scyphozoa were formerly considered to include the animals now referred to as the classes Cubozoa and Staurozoa, they now include just three extant orders (two of which are in Discomedusae, a subclass of Scyphozoa).[11][12] About 200 extant species are recognized at present, but the true diversity is likely to be at least 400 species.[11]
Class Scyphozoa
- Subclass Coronamedusae
- Order Coronatae
- Family Atollidae
- Family Atorellidae
- Family Linuchidae
- Family Nausithoidae
- Family Paraphyllinidae
- Family Periphyllidae
- Subclass Discomedusae
- Order Rhizostomeae
- Suborder Daktyliophorae
- Family Catostylidae
- Family Lobonematidae
- Family Lychnorhizidae
- Family Rhizostomatidae
- Family Stomolophidae
- Suborder Kolpophorae
- Family Cassiopeidae
- Family Cepheidae
- Family Mastigiidae
- Family Thysanostomatidae
- Family Versurigidae
- Order Semaeostomeae
- Family Cyaneidae
- Family Drymonematidae[13]
- Family Pelagiidae
- Family Phacellophoridae
- Family Ulmaridae
References
[edit]- ^ Jump up to: a b Liu, Yunhuan; Shao, Tiequan; Zhang, Huaqiao; Wang, Qi; Zhang, Yanan; Chen, Cheng; Liang, Yongchun; Xue, Jiaqi (2017). "A new scyphozoan from the Cambrian Fortunian Stage of South China". Palaeontology. 60 (4): 511–518. doi:10.1111/pala.12306.
- ^ Dawson, Michael N. "The Scyphozoan". Retrieved 2008-08-11.
- ^ Towle, Albert (1989). Modern biology. Austin, Texas: Holt, Rinehart and Winston. ISBN 978-0030139192.
- ^ Jump up to: a b Kramp, P. L. (1961). "Synopsis of the medusae of the world". Journal of the Marine Biological Association of the United Kingdom. 40: 1–469. doi:10.1017/s0025315400007347.
- ^ Jump up to: a b c d e Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 139–149. ISBN 978-0-03-056747-6.
- ^ Cartwright, P., Halgedahl, S.L., Hendriks, J.R., Jarrad, R.D., Marques, A.C., Collins, A.G., and Lieberman, B.S., 2007, Exceptionally preserved jellyfishes from the Middle Cambrian. PLOSONE Issue 10: e1121, p.1-7.
- ^ Richards, H.G., 1947, Preservation of fossil jellyfish: Bulletin of the Geological Society of America, v. 58, p. 1221.
- ^ Morris, M., and Fautin, D., 2001, Animal Diversity Web: University of Michigan Museum of Zoology, "Scyphozoa., Accessed: September 28, 2008.
- ^ Berking S, Herrmann K (2007). "Compartments in Scyphozoa". Int. J. Dev. Biol. 51 (3): 221–8. doi:10.1387/ijdb.062215sb. PMID 17486542.
- ^ Omori, Makoto; Eiji Nakano (2001). "Jellyfish fisheries in southeast Asia". Hydrobiologia. 451 (1/3): 19–26. doi:10.1023/A:1011879821323. S2CID 6518460.
- ^ Jump up to: a b Daly, Brugler, Cartwright, Collins, Dawson, Fautin, France, McFadden, Opresko, Rodriguez, Romano & Stake (2007). The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa 1668: 127–182
- ^ "Scyphozoa". WoRMS. World Register of Marine Species. Retrieved 30 July 2012.
- ^ Bayha, K. M., and M. N. Dawson (2010). New family of allomorphic jellyfishes, Drymonematidae (Scyphozoa, Discomedusae), emphasizes evolution in the functional morphology and trophic ecology of gelatinous zooplankton. The Biological Bulletin 219(3): 249–267
External links
[edit]
- Классификация и распространение класса Scyphozoa
- . Энциклопедия Британия (11 -е изд.). 1911.
| Базы данных управления авторитетом : национальный |
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