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The Scyphozoa are an exclusively marine class of the phylum Cnidaria, [2] referred to as the true jellyfish (or "true jellies"). The class name Scyphozoa comes from the Greek word skyphos ( σκύφος ), denoting a kind of drinking cup and alluding to the cup shape of the organism.
Craspedacusta sowerbii or peach blossom jellyfish [1] is a species of freshwater hydrozoan jellyfish, or hydromedusa cnidarian. Hydromedusan jellyfish differ from scyphozoan jellyfish because they have a muscular, shelf-like structure called a velum on the ventral surface, attached to the bell margin.
Rhopilema nomadica, the nomad jellyfish, is a jellyfish indigenous to tropical warm waters of the Indian and Pacific Oceans. Since 1970's it has been also found in Mediterranean Sea, where it entered via the Suez Canal ( Lessepsian migration ).
Jellyfish are slow swimmers, and most species form part of the plankton. Traditionally jellyfish have been viewed as trophic dead ends, minor players in the marine food web, gelatinous organisms with a body plan largely based on water that offers little nutritional value or interest for other organisms apart from a few specialised predators such as the ocean sunfish and the leatherback sea turtle.
In most crochet, the artisan usually has only one live stitch on the hook (with the exception being Tunisian crochet), while a knitter keeps an entire row of stitches active simultaneously. Dropped stitches, which can unravel a knitted fabric, rarely interfere with crochet work, due to a second structural difference between knitting and crochet.
Cassiopea ornata are photosynthetic due to a symbiotic relationship with the zooxanthellae that live below their tentacles. These algae feed on the sun and produce nutrients. The remaining nutrients become food for the jellyfish. These jellyfish are able to thrive because the mutualistic relationship with the algae and rarely have to hunt.
Stauromedusae are the stalked jellyfishes.They are the sole living members of the class Staurozoa and belong to the medusozoa subphylum of Cnidaria.They are unique among medusa jellyfish in that they do not have an alternation of polyp and medusa life cycle phases, but are instead interpreted as an attached medusa stage, with a lifestyle more resembling that of polypoid forms.
The cells making up these two body layers are relatively simple. Hydramacin [ 5 ] is a bactericide recently discovered in Hydra ; it protects the outer layer against infection. A single Hydra is composed of 50,000 to 100,000 cells which consist of three specific stem cell populations that create many different cell types.