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CNIDARIA. CLASSIFICATION OF PHYLUM CNIDARIA. The phylum C nidaria is represented by approximately 10,000 species . The phylum is classified into 5 classes. Hydrozoa (hydroids and siphonophores ) Anthozoa (corals and sea anemone) Cubozoa (box jellyfish) Scyphozoa (swimming jellyfish)
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CLASSIFICATION OF PHYLUM CNIDARIA • The phylum Cnidaria is represented by approximately 10,000 species. • The phylum is classified into 5 classes. • Hydrozoa (hydroids and siphonophores) • Anthozoa (corals and sea anemone) • Cubozoa (box jellyfish) • Scyphozoa (swimming jellyfish) • Staurozoa (stalked jellyfish)
CLASS HYDROZOA(hydra= sea serpent and zoa= animal) • These are called sea serpents because of numerous tentacles arising from their main body part. • These are small, predatory animals which may live solitary or colonial. • Most of the species are marine and few live in fresh water. • They have radial body symmetry. • Examples: Hydra, Tubularia, Obelia, Sertularia, Plumularia, Cunia, Polycolpa, Millepora, Physalia, Halistemma, porpita.
CLASS ANTHOZOA(Anthos=flower, zoa=animal) • These are called flower animals because of their floralappearance. • Anthozoans are characterized by absence of medusa stage in their development. • Instaed, they release sperm and eggs that form planula larva. • Asexual repro. By budding also takes place in some forms. • It is a large class with approximately 6,000 species. • These have biradial body symmetry with hexamerous, octomerousor polymerous arrangement of body parts. • Manubrium absent, gastrovascular cavity is divided into 8 or more compartments by vertical septa called mesenteries.
Continue…….. • The latter contain nematocysts. • Mesoglea is thick and cellular. • Examples: Xenia, Gorgonia, Heliopora, pennatula, Renilla, Tubipora, Clavularia, Metridium, Admasia, Favia, Madrepora, Astrea, Zoanthus, Epizoanthus, and Cerianthus.
CLASS CUBOZOA • These are generally known as Box jellyfish because of their cube shaped medusae. • Some spp. of box jellyfish produce extremely potent venum. • Stings from these animals are extremely painful and can be fatal to human. • These are also k/as Sea wasp because of their venomus sting. • Examples:Chironexfleckeri, Carukia, Barnesi, Chirodectes.
CLASS SCYPHOZOAGreek-skyphos= cup,because of cup shaped structure of animal. • These are commonly k/as jelly fishes. • These are exclusively marine animals with predominant medusa form, polyps are generally absent. • Body has tetramerous radial symmetry. • Venom is absent in medusa pouches. • Mesoglea is well developed and gelatinous in nature. • Examples are Aurelia, Pelagia, Rhizostoma, Pericolpa, andperiphylla.
CLASS STAUROZOA • These are little stalked jellyfishes (mostly upto 5cm in length with few upto 15 cm large). • They remain attached to the substrate( rock or algae mostly) for their entire life. • Earlier these animals have been described under class scyphozoa, but recent morphological and molecular studies has elevated them to separate class. • This class contain about 50 species and single order. • Example: Haliclystus, Lucernaria.