TAMU BIOL 112 - CH33 (9 pages)

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CH33



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CH33

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Pages:
9
School:
Texas A&M University
Course:
Biol 112 - Introductory Biology Ii
Introductory Biology Ii Documents

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Chapter 33 Invertebrates About 95 of all animal species are invertebrates Composed of about 35 phyla Most are aquatic marine the big exception to this are the arthropods Porifera Closest group to the earliest animals Aquatic mostly marine Lake overall symmetry o Sessile as adults Lack true tissues 33 4 o Digestion gas exchange waste removal all occur at the cellular level o Cell types often change roles Body supported by hard spicules and or protein fibers called spongin Suspension feeders o Feed by passing water across a stick structure that catches tiny food bits o Choanocytes create currents that trap food Reproduction o By fragmentation o Sexually hermaphroditic o Flagellated larva disperses then settles Cnidaria Radial symmetry and diploblastic oral and aboral sides in attaches species 2 body forms in the life cycle o Sessile polyp o Planktonic free swimming medusa Body is sac like o 2 tissue layers with gel mesoglea in between Direct gas exchange between cells and water o Have a gastro vascular cavity 1 opening digestive sac mouth and anus as one hole Extracellular and intracellular digestion Gastro vascular cavity distributes nutrients to the entire body Aquatic sit and wait carnivores o Catch prey with stinging tentacles with cnidocytes Reproduction is sexual or asexual budding o Many cycle through polyp and medusa forms Hydrozoans o Ex Hydra is freshwater o All other classes are strictly marine o Most alternate between polyp and medusa 33 8 o Many are colonial polyps Obelia o Unusual body forms Portuguese Man of War Scyphozoans o Jellies medusa form predominately o Bioluminescent florescent o Nematocyst Cubazoans o Box shaped medusa with eyes o Very toxic sting ex Sea Wasp o Eyes why No brain to process images but can sense Anthozoans o Polyp form only o Anemones are solitary o Corals mostly colonial reef builders Ctenophores Comb jellies radial symmetry and diploblastic o Transparent medusa like body o Moves by 8 comb like plates of fused cilia Marine sit



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