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Two Coelomate Lineages Protostomes Deuterostomes Mollusks Echinoderms Annelids Chordates Arthropods Cleavage Patterns Protostome embryo (spiral cleavage) Blastopore becomes mouth Deuterostome embryo (radial cleavage) Blastopore becomes anus In-text figure Page 426 Phylum Mollusca Representative organisms: Coelomates snails, slugs, oysters, clams, octopuses, squids Have a true coelom Protostomes: Blastopore becomes mouth Phylum Mollusca Body plan has 3 main parts: Muscular foot used for movement Visceral mass covering the internal organs Mantle covers the visceral mass (may produce a protective shell) Cuttlefish Body Plan Closed circulatory system with heart and accessory heart esophagus digestive kidney stomach gland Figure 25.22 Page 429 brain arm jaw tentacle mantle reproductive internal siphon ink sac heart accessory organ shell radula anus gill heart Phylum Annelida Representative Organism: earthworm Annelids have segmented bodies Metanephridia (similar to kidneys) Worms are hermaphrodites Remove wastes from the blood Produce both sperm and eggs Setae provide traction for burrowing in the soil Earthworms eat their way through the soil 33-23-EarthwormLocomot-B.mov