Introduction to Cnidaria 0.0 / 5 ? BiologyInvertebrate ZoologyUniversityNone Created by: Becky_BerryCreated on: 04-10-23 12:15 Structure of Cnidarians adults appear as free swimming medusae or sessile polyps radially symmetrical nutrients taken in by phagocytosis or pinocytosis in the gastrovascular cavity predigestion takes place intracellularly but digestion itself takes place within the cells more complex than sponges differentiated from other animals by cnidocytes three types of cnidocytes: nematocysts, spirocysts, and ptychocysts suggested that cnidarians evolved from triploblastic ancestors, despite being diploblastic 1 of 3 Taxonomy and Diversity of Cnidaria Cnidaria: a phylum that comprises the sea anemones, jellyfish, and corals, and which are known from the late Precambrian ANTHOZOA: a class of exclusively polyploid, marine cnidarians that are solitary or colonial, and usually sedentary MEDUSOZOA: a clade of Cnidaria that is often considered a subphylum, containing jellyfish, hydrozoans, and the parasitic Polypodiozoa HYDROZOA: class also known as the hydroids or freshwater 'jellyfish' SCYPHOZOA: class referred as the true jellyfish STAUROZOA: class referred to as stalked jellyfish CUBOZOA: class referred to as box jellyfish POLYPODIOZOA: class that contains a single genus of cnidarians that parasitise the eggs of sturgeon and other fishes MYXOZOA: a subphylum of aquatic cnidaria animals, also known as the slime animals, all of which are obligate parasites 2 of 3 Reproduction, Development, and Lifecycle of Cnidar planula: a free-swimming coelenterate larva with a flattened, ciliated, solid body larval form of various cnidarians and some ctenophores form either from a fertilised egg or from a polyp polyp: one of two forms found in Cnidaria, are roughly cylindrical in shape and elongated at the axis of the vase-shaped body solitary polyps have an aboral end attached to the substrate by a pedal disc colonies of polyps are either directly or indirectly connected to other polyps HYDROZOA reproduce by budding by longitudinal fission metamorphosis: a change of the form or nature of a thing into a completely different one metagenesis: an alternation of generations in animals, especially a regular alternation of a sexual and an asexual generation 3 of 3
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