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Bio Notes Jan 27

Bio Notes Jan 27 - Bio Notes Key Green Subphylum Blue...

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Bio Notes January 27, 2009 Key: Green- Subphylum Blue- Phylum Highlight- class Key Concepts: Biologists classify animals based on their body plan and features of their early development Animal kingdom has 2 major subkingdoms: Parazoa- simple body plan (sponges)- no true tissues Eumetazoa- True tissues Eumetazoa: Radiata- radial symmetry (2 cuts) Bilateria- with bilateral symmetry (1 cut) -Protostomia -Acoelomates (simplest) -Pseudocoelomates -Coelomates -Deuterostomia -Coelomates CHAPTER 29: Parazoa- Sponges o Diverged early, but function similar to choanoflagellates o Characterized by flagellate collar cells o Aquatic (marine), vary in shape and color, some symbiotic bacteria give them color Depend on zooxanthellae (photosynthetic algae) that live in cells in digestive area for nutrition- symbiotic. Algae gives coral O2, C, and N; coral provides NH3 to algae via waste products; for nitrogenous prods. o Sponge body - sac with tiny openings or pores (ostia) for water to enter Porocytes regulate pore diameter o Central cavity - (spongocoel)- not digestive open end (osculum) for water to exit o Body wall extensively folded system of canals, increased surface area for food capture o Collar Cells (choanocytes) - beat their flagella producing current of water that then enters through pores. Brings food, oxygen to cells and carries away CO2 and waste. Water passes through the spongocoel and exits through osculum. Food trapped. o Mesohyl - gelatin like layer between inner and outer body layer, supported by spicules (secreted by amoeboid cells) consisting of fibrous sponging, CaCO3 or silica o Amoeboid cells - transport nutrients to epidermal cells
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Undigested food goes through osculum into water. o Sponge structure: Adult is sessile and larvae are flagellate Adult may move slowly via cells on sponge’s lower surface o Sponge Cells: Loosely associated Do not form true tissues Certain cells are specialized for nutrition, support, contraction, or reproduction Repair and regenerate o Sponge Reproduction: Asexual- small fragment or bud breaks free and forms new sponge; form colony Sexual- most are hermaphrodites: Some amoeboid cells become eggs and some become sperm at different times Cross-fertilize by releasing sperm into water, which are taken up by other sponges of same species Fertilization and development in mesophyl Zygote develops into flagellate larva Attaches and becomes sessile Eumetazoa Radiata: o Animals with radial symmetry and two tissue layers (diploblastic) o Cnidaria (phylum)- Hydras, jellyfish, sea anemones Radial symmetry Hollow sac with mouth surrounded by tentacles at one end Cnidocytes (contain nematocysts) Stinging organelles present in tentacles Cnidocil is a mechanoreceptor- reacts to touch or dissolved chemicals When cnidocytes are stimulated, the nematocysts discharge a thread that penetrates or entangles the prey Polyp and/or medusa forms Table 29-2 Cnidarian’s life cycle Sessile polyp stage o
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Bio Notes Jan 27 - Bio Notes Key Green Subphylum Blue...

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