Scyphozoa
Chrysaora sp.
- Flags jellyfish ( Semaeostomeae )
- Wreath jellyfish ( Coronatae )
- Rhizostomae ( Rhizostomeae )
Jellyfish Jellyfish screen or disc ( Scyphozoa ) are a class of Cnidarians ( Cnidaria ). They are also known as True jellyfish. The screen jellyfish form three orders: wreath jellyfish ( Coronatae ), flags jellyfish ( Semaeostomae ) and Rhizostomae ( Rhizostomeae ). Among the Scyphozoa includes about 130 species. The usually solitary living animals are characterized by large jellyfish and small polyps. Reproduction takes place alternately asexually by pinch of Ephyralarven from sessile polyps ( strobilation ), and gender (called metagenesis ).
Features
Umbrella jellyfish are transparent animals of a thick gelatinous mass with springing at the screen edge tentacles. Here sit light and tactile organs that Rhopalien. The screen jellyfish have swimming bells. The tentacles can be up to 30 m long, sit on them the poisonous nematocysts. The body of a jellyfish is 98 % water. Some umbrella jellyfish are only a few millimeters in size, but some can have up to 2 m in diameter.
Most of the coastal features form in the larval stage a " Scyphopolypen " with exactly four Gastralkammern. He transforms into a pile of tiny asexual Medusenlarven, referred to as a strobilation process. The Meduslarve is also called " Ephyra " and after a while in the plankton for jellyfish.
Occurrence
Most jellyfish species are restricted to the coastal areas, because they are dependent for their reproduction during the polyp generation in fixed sedentary life on a suitable substrate. But there are also deep-sea jellyfish, which multiply in the open ocean and do not form polyps generation.
Types (selection)
- Moon Jellyfish ( Aurelia aurita )
- Cassiopea andromeda
- Nettle Jellyfish ( Chrysaora hysoscella )
- Fried egg jellyfish ( Cotylorhiza tuberculata )
- Mastigias papua (eg in Jellyfish Lake of Palau )
- Nemopilema nomurai
- Crown jellyfish ( Periphylla periphylla )
- Phyllorhiza punctata ( Phyllorhiza punctata)
- Punctata ( Rhizostoma octopus )
- Rhopilema esculentum
- Rhopilema Verrilli
- Stomolophus meleagris
- Stomolophus nomurai