chapter30%20-%20proteostomes%20Spring%202008%20_1_

chapter30%20-%20proteostomes%20Spring%202008%20_1_ - The...

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Unformatted text preview: The Animal Kingdom: Bilateria - The Protostomes Chapter 30 Cephalization evolved with bilateral symmetry; sensory structures; nerve cells in head form a brain, nerve cord extends toward the rear Protostomes Characterized by Bilateral symmetry spiral and determinate cleavage Initial development of mouth from blastopore Three body layers (triploblastic) Contain a-coelomate, pseudo-coelomate and coelomate members Phylum Platyhelminthes ( acoelomate flatworms) No organ for circulation or gas exchange Gastrovascular cavity (digestive system) with one opening (mouth) Many are hermaphrodites Beginnings of cephalization (head) with concentration of sense organs and nerve cells (simple brain) at anterior end Dugesia- free living Planarians (Class Turbellaria) (Fig 30-1) Auricles: Mouth, pharynx, gastrovascular cavity: Ladder-type nervous system: simple brain Tapeworm (Class Cestoda) Fig 30-3 *** Parasites; scolex (suckers) Body segments (proglottids) capable of reproducing 1000s eggs! shed in feces Food absorbed across body wall; no digestive tract, no defined sense organs; complex life cycle (platyhelminthes include liver fluke -Trematode ..) Phylum Rotifera Fig 30-15 ( pseudocoelomates ) Wheel animals; multi-cellular, moist fresh water habitat Lie in dormant state for years Spinning wheel crown of cilia; Nervous system, brain and sense organs No cell division after embryonic development growth results from increase in cell size (hypertrophy) Phylum Nematoda...
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This note was uploaded on 03/08/2011 for the course BIO 119 taught by Professor Transue during the Spring '09 term at Rutgers.

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chapter30%20-%20proteostomes%20Spring%202008%20_1_ - The...

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