8. Pseudocoelomates and Annelid Intro

8. Pseudocoelomates and Annelid Intro - 1 Phylum Phylum...

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Unformatted text preview: 1 Phylum Phylum Nemertea Nemertea Pseudocoelomate Pseudocoelomate Phyla Phyla Reminder from last week Intro to Phylum Annelida - lab this week Phylum Nemertia Phylum Nemertia ribbon worms ribbon worms (= (= Rhynchocoela Rhynchocoela ) Similar to flat worms Similar to flat worms Acoelomate Acoelomate (?), Organ Grade (?), Organ Grade Ciliated Epithelium Ciliated Epithelium Protonephridial Protonephridial Excretory system Excretory system Nervous system w/ sense organs Nervous system w/ sense organs Unlike flatworms Unlike flatworms one way gut (mouth & anus) one way gut (mouth & anus) closed closed circulatory system circulatory system proboscis proboscis Special Features: Proboscis Proboscis- complex organ Stylet- inject neurotoxins, glad cells subdue prey Rhynchocoel = proboscis cavity eversion - hydrostatic pressure- contraction of muscles in wall of proboscis sheath withdrawn - retractor muscle Fluid filled cavity for proboscis = Rhynchocoel Proboscis is everted by hydrostatic pressure It is retracted by contraction of the proboscis muscle The stylet has toxins to immobilize and kill prey Digestive System / Nutrition predators one way gut mouth => gut => anus allows specialization sequential digestion & absorption Nervous system brain - 2 nerve cords - lateral with connections many sensory structures 2 Circulatory System Circulatory System Closed Closed- lateral blood vessels, lateral blood vessels, dorsal vessel & sinuses dorsal vessel & sinuses large vessels contractile large vessels contractile transports nutrients, O transports nutrients, O 2 , , hormones, waste, etc. hormones, waste, etc. Excretory System Excretory System Protonephridia Protonephridia- close assoc. with circulatory close assoc. with circulatory system system Reproduction Simple Dioecious Free Spawn (external fertilization) Development - direct or indirect - Pilidium Larva Asexual Repro - fragmentation very good at regeneration Evolution: Relatives of flatworms ?...
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This note was uploaded on 01/27/2010 for the course BIO 37282 taught by Professor Padilla during the Fall '10 term at SUNY Stony Brook.

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8. Pseudocoelomates and Annelid Intro - 1 Phylum Phylum...

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