Zoology Exam1 Notes - Zoology Exam#1 Phylum...

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Zoology Exam #1: Protozoans Ctenophores Phylum Porifera -Demospongiae: Largest class -Pharmacological: Antimicrobial, Anti-inflammatory, Anti-Tumor -Success due to aquiferous system and totipotent nature of sponge cells Body -Outer surface: Pinacoderm- made of pinacocytes -Small holes pull water through to choanoderm by beating of choanocytes -Dermal Pores: surrounded by several cells -Ostia: surrounded by one cell -Cuticle may cover or replace pinacoderm -Not found in Hexactinellida (noncellular dermal membrane instead with incurrent pores) -Middle: Mesohyl -Roles in digestion, gamete production, secretion of skeleton, and transport of nutrients/waste by amoeboid cells -Most cells here can re-differentiate, except those for reproduction or skeletal formation -Inner surface: Choanoderm- made of choanocytes -Asconoid: if simple and continuous -Syconoid: if folded -Leuconoid: if subdivided into flagellated chambers -Cells that secrete skeleton -Collencytes (collagen) -Lophocytes (collagen tail) -Spongocytes (spongin) -Sclerocytes (calcium carbonate and siliceous spicules) -Contractile Cells -Myocytes: found in mesohyl around oscula and major canals -Contain many microtubules and microfilaments in cytoplasm -Purely mechanically stimulated -Archaeocytes -Amoeboid cells capable of differentiating into any other type of cell -Major role in digestion and food transport Grades -Asconoid -Vase-shaped, tubular -Central cavity: Atrium/Spongocoel; opens to outside via osculum -Porocytes: extend through pinacoderm, mesohyl, and choanoderm into spongocoel -Ostium/Incurrent Pore: external openings of porocyte canal -Water Flow: Ostium Spongocoel (over choanoderm) Osculum -Syconoid
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-Thicker mesohyl of “two” layers -Cortex: outer layer containing skeletal elements different from those in inner layer -Dermal Pores: incurrent openings lined by several cells -Choanocytes restricted to choanocyte chambers (aka flagellated chambers or radial canals) -Chambers open into atrium through apopyle -Dermal pores lead to chambers by prosopyles -Water flow: Dermal Pore Incurrent Canal Prosopyle Choanocyte Chamber Apopyle Spongocoel Osculum -Leuconoid -Thickest mesohyl -Further division of chambers (clover-shaped) -Spongocoel becomes series of excurrent canals that carry water from choanocyte chambers to oscula -Water flow: Dermal Pore Incurrent Canal Prosopyle Choanocyte Chamber Apopyle Excurrent Canal Osculum Nutrition -Phagocytosis: digestion occurs in food vacuole at time of capture -Choanocyte Capture: food particles partly digested in choanocytes and passed on to a mesohyl archaeocyte for final digestion -Filter Feeders!! Response to Environment -Closure of ostia or oscula -Canal constriction -Backflow All reduce/stop water flow -Reconstruction of flagellated chambers Reproduction -Asexual -“Pinching off” -Formation of gemmules -Thick collagenous coat with siliceous spicules -Fresh water sponges (ie, Spongilla ) -Budding -Marine -Sexual -Sperm arise from choanocytes -Eggs arise from choanocytes or archaeocytes
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