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[5.1] Porifera.docx

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York University
BIOL 2030
Scott Kelly

Porifera - Sponges Porifera [Sponges] Phylum of simple multicellular animals, with a simple body enclosing a single central cavity (in simple sponges) or penetrated by numerous interconnected cavities. The body wall consists of an outer layer of epithelium seprated from an inner layer of ciliated choanocytes (feeding cells) by a mesogleal layer. There are no nerve or muscle cells. Water is drawn into the internal cavities through pores (ostia), food particles are taken up by the choanocytes and the water flows out through a large pore (the osculum). There are three classes: the Calcarea, the calcareous sponges, which have spicules of calcium carbonate embedded in the mesoglea and projecting to the outside; the Hexactinellida, the glass sponges, with silica spicules; and the Demospongia, which includes some species with silica spicules and some species without, and which often have the body wall strengthened by a tangled mass of fibres (ex. The bath sponge) Apopyle Exhalent pore of sponges (leading from radial canal to spongocoel) Archeocyte Amoeboid cells found in the mesohyl of sponge Choanocytes Flagellated cell, with protoplasmic collar around base of the flagellum, lining body cavity of sponges. Involved in uptake of food particles from water drawn into cavity by the beating of the flagella Dermal ostium Skin ostium, present in leuconoid sponges Incurrent canal Ectoderm-lined canas which admit water into sponges (no choanocytes) Mesohyl [mesoglea] gelatinous, non-cellular layer between the inner and outer body wall in sponges and coelenterates. Osculum Large pore in body wall of sponge through which water flows out the body cavity Ostium Opening from exterior into body cavity of sponges through lateral wall, through which water is drawn in Pinacocytes Flattened plate-like cells of outer epithelium of sponges Prosopyle Inhalent pore of sponges Radial Canal [Coanocyte Chamber] Spicules Small needle-like structure or part, of silicate or calcium carbonate, providing structural integrity in sponges Spongin Fibrous protein component of the horny sponges, such as bath the sponge Spongioco
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