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Flatworms, Roundworms, & Segmented Worms

Flatworms, Roundworms, & Segmented Worms. Phylum Platyhelminthes. Flatworms Flat and thin bodies Bilateral symmetry Most are parasitic . Phylum Platyhelminthes. Flatworms include planarians, flukes, and tapeworms 20,000 species of flatworms. Miscellaneous Information- Flatworms.

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Flatworms, Roundworms, & Segmented Worms

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  1. Flatworms, Roundworms, & Segmented Worms

  2. Phylum Platyhelminthes • Flatworms • Flat and thin bodies • Bilateral symmetry • Most are parasitic

  3. Phylum Platyhelminthes • Flatworms include planarians, flukes, and tapeworms • 20,000 species of flatworms

  4. Miscellaneous Information- Flatworms • Movement- use of moving bodies of water or damp soil, or larger animals transporting them • Nutrition- parasitic; the flatworm will take in food through same opening it eliminates waste • Circulatory system- Gastrovascular cavity with one opening • Digestion and excretion occur through same opening • Reproduction- flatworm splits in two forming a new flatworm

  5. Tapeworms Information • Can get tapeworm infection by ingestion of food or water contaminated with tapeworm eggs or larvae • Can cause intestinal infections • Symptoms- poor appetite, diarrhea, weakness, gastrointestinal discomfort

  6. Phylum Nematoda • Roundworms • Ex. Pinworms and hookworms • 90,000 species of nematodes • Bilateral Symmetry • Live in wet soil or water • Eat dead leaves and other materials • Some eat insects that destroy plant roots • Some destroy plant roots

  7. Flatworm Head • Head holds attachment hooks for host attachment • 2 eyespots to help detect light • Also contains brain called 2 simple brains called ganglia- simple bundles of nerves

  8. Phylum Nematoda • Some roundworms can live in humans and make them sick • Roundworms have a complete digestive tract with 2 openings

  9. Nervous System of Roundworms • Two nerve cords that transmit impulses in the roundworm

  10. Miscellaneous Information- Roundworms • Reproduction- sexually, eggs deposited in soil after fertilization • Bilateral symmetry • No formal respiration, circulation, skeletal systems

  11. Phylum Nematoda

  12. Phylum Annelida • Annelids are segmented worms • Bodies are divided into many sections or segments • Live in moist soil, freshwater, or saltwater • 15,000+ species of annelids • Examples: earthworms and leeches

  13. Phylum Annelida • Earthworms • Have bristlelikeSetae on each segment- helps in movement • Tunnel through soil to eat small pieces of food • Tunnels will loosen the soil and allow air to enter which helps plants to grow

  14. Leeches and Us • Used in medicinal treatment • Abscesses, painful joints, glaucoma, myasthenia, and to heal venous diseases and thrombosis

  15. Phylum Annelida

  16. Miscellaneous Information- Segmented Worms • Nervous system- ganglia nerve centers in each segment that are connected by nerve cords to brain • Closed circulatory system- like humans • Gas exchange through skin- need for worm to live near water • Digestion- complete internal digestive tract that runs length of body • Gizzard- muscular sac and hard particles help grind soil and food before they pass into intestine Nephridia- collect/remove waste from each segment Pg. 731 is a good reference for earthworm body

  17. Miscellaneous Information- Segmented Worms • Reproduction- Hermaphrodites • Produce both eggs and sperm

  18. Phylum Annelida • Leeches • Eat small invertebrates • Can attach to skin of vertebrates and feed on its blood • Anesthetics in chemicals of bite to prevent pain • Leech secretes chemical so blood does not clot

  19. Bilateral Symmetry and Body Plans • All bilaterally symmetrical animals developed from 3 embryonic cell layers: • Ectoderm • Endoderm • Mesoderm • 3 types- Acoelomates, Pseudocoelomates, Coelomates

  20. Acoelomates • Develop from the 3 layers but have no body cavities • Digestive tract extends throughout body • May have been first group of animals to evolve • Ex. Flatworms

  21. Acoelomates

  22. Pseudocoelomates • Develop from the 3 layers • BUT also has a space that develops between the endoderm and mesoderm- called a pseudocoelom(difference between flatworm and roundworm)

  23. Pseudocoelomates

  24. Coelomates • Body cavities form from Coelom (fluid filled space that is completely surrounded by mesoderm where specialized organs and organ systems, serves to cushion and protect organs) • Humans, insects, fishes • Example: Earthworm • Greatest diversity among animals

  25. Coelomates

  26. Earthworm

  27. Compare and Contrast • Flatworm and Earthworm digestive tracts • One opening to flatworm’s digestive tract (pharynx) • Earthworm’s digestive tract has 2 openings (mouth and anus)

  28. 3 types of worms

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