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CANAL SYSTEM IN Porifera

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Canal system in Porifera (sponges) Body of all sponges is the perforated by large number of apertures through which water enters Inside body and flows through a system of criss-crossing canals collectively forming the canal system which is a characteristic feature of poriferans. Following types of canal systems are found in sponges: Ascon type, with flagellated spongocoel Sycon type, with flagellated radial canals Leucon type, with flagellated chambers Rhagon type, with conical shape and broad base ASCON TYPE This is the simplest type of canal system and is found in  Leucosolenia  and other homocoela. Ostia are present on the surface of body and lead directly into the spongocoel, which is lined by flagellated choanocyte cells. Spongocoel opens to the outside through a narrow circular opening, the  osculum  located at the distal free end of the sponge body. Water enters through ostia into spongocoel and goes out of body through the  osculum . SYCO...
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Invertebrate Zoology By Brusca and Brusca

"Invertebrates" 2nd edition presents a modern survey of the 34 animal phyla (plus the Protista) and serves as both a college course text and a reference on invertebrate biology. It is organized around the themes of bauplans (body plans) and evolution (phylogenetics). Detailed classifications, phylogenetic trees, and references for all phyla are provided. The text is accompanied by detailed line drawings and - new to this edition - four-colour photographs. Other key changes from the 1st edition (1990) include: the incorporation of all the new developments in phylogenetics, developmental biology and molecular genetics; major changes at the highest levels among the invertebrates; three phyla that appeared in the original book Pentastomida, Pogonophora and Vestimentifera no longer exist, and an entire new phylum, Cycliophora, has been erected. Moreover, this edition discusses recent work in molecular systematics, and there is a large new section on "Kingdom Protista" (...
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