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Mollusks and Segmented Worms

Mollusks and Segmented Worms. Chapter 27 Biology Auburn High School Pgs. 740 – 757 . 27.1: Mollusks. p. 741 – 747 . Characteristics of Mollusks. Phylum Mollusca Meaning – soft Bilateral symmetry, coelomate, 2 body openings, a muscular foot, & mantel Habitat

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Mollusks and Segmented Worms

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  1. Mollusks and Segmented Worms Chapter 27Biology Auburn High School Pgs. 740 – 757

  2. 27.1: Mollusks p. 741 – 747

  3. Characteristics of Mollusks • Phylum Mollusca • Meaning – soft • Bilateral symmetry, coelomate, 2 body openings, a muscular foot, & mantel • Habitat • Most live in the ocean; some freshwater or moist terrestrial habitats • Feeding • Use a radula to drill, scrape, grate, or cut food • Tongue like organ with rows of teeth

  4. Characteristics of Mollusks • Reproduction • Most have separate sexes and reproduce sexually via external fertilization • Terrestrial species are hermaphrodites

  5. 3 Classes of Mollusks • Class Gastropoda • One-shelled mollusks (Stomach-footed mollusk); most have open circulatory systems • Can be plant eaters, predators or parasites • Examples: Snails, abalones, conches, slugs

  6. 3 Classes of Mollusks • Class Bivalvia • Two-shelled mollusks • Filter-feeders • Use foot to burrow • Marine or freshwater • Examples: • clams, oysters, scallops

  7. 3 Classes of Mollusks • Class Cephalopoda • Head-footed mollusks • All marine • Move by jet propulsion • Internal shell • Feet have tentacles w/ suckers, hooks or adhesive structures • Most have a closed circulatory system • Most excrete an ink for protection • Examples: octopus, squid, cuttlefish, chambered nautilus (only one with external shell)

  8. Pictures of Cephalopods

  9. 27.2: Segmented Worms p. 748 – 753

  10. Characteristics of Segmented Worms • Phylum Annelida • Meaning – anellus = tiny ring • Bilaterial symmetry; coelom; 2 body opening; bodies are cylindrical and segmented • Habitat • Most environment except: frozen soil and dry sand / soil • Locomotion • All use setae (tiny bristles on each segment)

  11. Characteristics of Segmented Worms • Reproduction • Hermaphrodites (earthworms and leeches) • Sexual reproduction via mating (bristle worms) • Feeding • Complete digestive track • Eat soil or blood • Significance • Earthworms aerate and fertilize the soil • Leeches are used medically for limb reattachment

  12. Characteristics of Segmented Worms • Examples: • Earthworms • Leeches • Bristleworms • Lug worms • Plumed worms • Sea mice • Fan worms

  13. Pictures of Segmented Worms

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