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Cnidarians are known for their ability to rapidly heal and regenerate their tissues, [12] a function that C. hemisphaerica also possesses. [13] This makes Clytia an ideal candidate for studying the dynamics of tissue regeneration and epithelial wound-healing in-vivo, since the organism's small size allows its healing process be filmed under a ...
Pacific sea nettles, Chrysaora fuscescens. Cnidaria (/ n ɪ ˈ d ɛər i ə, n aɪ-/ nih-DAIR-ee-ə, NY-) [4] is a phylum under kingdom Animalia containing over 11,000 species [5] of aquatic invertebrates found both in fresh water and marine environments (predominantly the latter), including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites.
Polypodium was long considered a unique intracellular parasite among cnidarians. [6] [7] Its hosts include 14 species of Acipenser, 2 species of Huso, Polyodon spathula [6] and Scaphirhynchus platorynchus. [2] Polypodium hydriforme is an endocellular parasite with an unusual life cycle, a peculiar morphology, and high rates of DNA evolution.
Like other cnidarians they possess cnidocysts, which were referred to as "polar capsules" before the discovery that myxozoans are cnidarians. These cnidocysts fire tubules as in other cnidarians; some inject substances into the host. However, the tubules lack hooks or barbs, and in some species are more elastic than in other cnidarians.
The order Blastocladiales, originally within the Chytridiomycota, are now classified as a separate phylum, the Blastocladiomycota. [16] The Neocallimastigales, originally an order of anaerobic fungi of the class Chytridiomycetes, found in the digestive tracts of herbivores, was later raised to a separate phylum, the Neocallimastigomycota. [15]
The cnidae, the explosive cells characteristic of the Cnidaria and used in prey capture and defence, are of a single type, there being nematocysts but no spirocysts or ptychocysts. [4] In contrast, the anthozoan life cycle involves a planula larva which settles and becomes a sessile polyp, which is the adult or sexual phase. [11]
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.
Unlike some other cnidarian groups, the lining of the central cavity lacks stinging nematocysts, which are found only on the tentacles and outer surface. All colonial hydrozoans also include some polyps specialized for reproduction. These lack tentacles and contain numerous buds from which the medusoid stage of the life cycle is produced.