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Annelids and Mollusks

Annelids and Mollusks. Leech. Clam. Earthworm. Annelids. Annelida  Marine Sandworms, earthworms, and leeches (segmented worms) Classes Polychaetes -> Marine worms, fire worms, feather dusters Oligochaetes  earthworms Hirudinea  leeches. Annelids. Earthworm. Polychaete (Ragworm).

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Annelids and Mollusks

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  1. Annelids and Mollusks Leech Clam Earthworm

  2. Annelids • Annelida Marine Sandworms, earthworms, and leeches (segmented worms) Classes • Polychaetes -> Marine worms, fire worms, feather dusters • Oligochaetes  earthworms • Hirudinea  leeches

  3. Annelids Earthworm Polychaete (Ragworm) Leech

  4. Reproduction • Mostly Sexual • Aquatic worms shed sperm and eggs into water • Earthworms & leeches are hermaphroditic (individuals fertilize each others eggs) Earthworm Mating

  5. Characteristics of Annelids • “Means tiny rings” • Have 5 characteristics of higher organisms • Bilateral symmetry • Cephalization • Tubular gut • Coelom • Segmentation

  6. Segmentation • Allows organism to attain larger size • Each segment separated by a wall called a septum • Nephridia  found in each segment; removes excess water & wastes • Muscle in each segment contract sequentially for movement • Each segment contains nerve cords connected to the brain

  7. Digestive System • 2 organs for Digestion • Crop -> stores food • Gizzard  grinds food

  8. Mollusks • Includes snails, clams, oysters, scallops, Squid, and Octopus • Characteristics of Mollusks • 2nd most numerous phylum • Ceolomates allows for movement and digestion at same time • Trochophore Free swimming larval stage

  9. Body Plan of Mollusks • Head-foot region  contains head (ganglia) and foot (muscle used for locomotion) • Visceral Mass contains heart + organs • Shell shell is made of Calcium carbonate; • Mantle epidermal layer that secretes Calcium carbonate; makes the shell • Ganglia Central Nerves behind mouth • Radula specialized tongue with teeth used for scraping algae or cutting plants

  10. Head-Foot Region

  11. Radula Circular Rows of Moving Teeth

  12. Gastropods • Includes Snails + Conch • Land snails are hermaphroditic; aquatic snails have separate sexes • Nudibranches “Naked gill” slugs… No shell

  13. Snails and Conch Conch Apple Snail Burgundy Snail

  14. Bivalvia • Includes clams, oysters, and scallops • Most are filter feeders through tubes called siphons

  15. Bivalves Clams Scallops Oysters

  16. Cephalopods • Includes Octopus and Squid • Free swimming Mollusks • Advanced nervous system with distinct brain (largest invertebrate brain) • Chromatophores are epidermal pigment cells that release ink when threatened

  17. Giant Squid Swimming Next to Diver

  18. Cephalopods

  19. Giant Pacific Octopus

  20. Scary-Looking Octopus

  21. I’m an Octopus!

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