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Unsegmented Worms

Unsegmented Worms. Flatworms. Flatworms. Belong to the phylum platyhelminthes . (Plat = flat) There are three classes: Turbellaria Trematoda Cestoda. Characteristics of Flatworms. They are acoelomates (they don’t have body cavities) They have bilateral symmetry Show cephalization

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Unsegmented Worms

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  1. Unsegmented Worms

  2. Flatworms

  3. Flatworms • Belong to the phylum platyhelminthes. (Plat = flat) • There are three classes: • Turbellaria • Trematoda • Cestoda

  4. Characteristics of Flatworms • They are acoelomates (they don’t have body cavities) • They have bilateral symmetry • Show cephalization • Respiration through skin • Single opening to digestive tract (pharynx)

  5. Class Turbellaria • Spade-shaped head and two eyespots • Eat protozoans for scavenge • Flame cells remove waste • Are hermaphrodites (have male and female reproductive parts) • Can reproduce by regeneration • Are free-living

  6. Class Trematoda • Are parasitic flukes • Have suckers on both ends of the body • Can live inside or outside of host

  7. Class Trematoda • Nervous and excretory systems like turbellarians • Hermaphrodites • Have complex life cycles

  8. Fluke Life-Cycles The long and complex life-cycle of the fluke can be made easier to understand through the use of a nonsense mnemonic : Every - EggMirror - Miracidium (free-living in water)Spotted - Sporocyst (in snail)Red - Redia (in snail)Certainly - Cercaria (free-living in water/snail)Met - Metacercaria (in 2nd intermediate host)Approval - Adult

  9. Class Cestoda • Parasitic • Tapeworms • Long, ribbon-like bodies • Absorbs nutrients from host • Hermaphrodites

  10. Tapeworm Anatomy

  11. Roundworms Roundworms

  12. Roundworms • Belong to phylum Nematoda • Pseudocoelomates (fluid filled body cavity) • Slender bodies that taper on both ends • Have mouth and anus • Can be free-living or parasitic

  13. Pinworms live in human intestines

  14. Trichinosis- a disease from eating infected pork

  15. Cysts in Contaminated Pork

  16. Rotifers • Known as rotifers or wheel animals • Transparent, free-swimming microscopic animal • Freshwater & marine • Have a ring of cilia around mouth that rotates like a wheel to bring in food • Feed on unicellular algae, bacteria, & protozoa

  17. Rotifers • Have a muscular organ called the mastax behind the pharynx to chop food • Nervous system composed of anterior ganglia & 2 long nerve cords • Show cephalization (head end) • Have 2 anterior, light-sensitive eyespots

  18. Rotifer Anatomy

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