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WORMS

WORMS. Flatworms: Phylum Platyhelminthes. Soft and Flat Tissues and Internal Organ Systems 3 embryonic germ layers (Ecto, Meso, & Endoderm) Bilateral symmetry Cephalization Acoelomates -without coelom (no fluid-filled body cavity). Feeding.

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WORMS

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  1. WORMS

  2. Flatworms: Phylum Platyhelminthes • Soft and Flat • Tissues and Internal Organ Systems • 3 embryonic germ layers (Ecto, Meso, & Endoderm) • Bilateral symmetry • Cephalization • Acoelomates-without coelom (no fluid-filled body cavity)

  3. Feeding • Mouth/anus with pharynx (muscular tube that moves food and waste) • Gastrovascular cavity – digestion/absorption • Parasites – simple or no digestive system b/c feed on blood, tissue fluids, or cell pieces of host • Carnivore • Scavenger • Parasitic

  4. Respiration, Circulation, Excretion • Diffusion (transport O2 and nutrients) through body walls • Flame cells – remove excess water and waste • Connected to pores in the skin

  5. Response • Ganglia – controls N.S. (nerve cell cluster) • Eyespot – detects light changes • Some have specialized cells to detect chemicals, food, etc.

  6. Movement • Cilia on epidermal cells for gliding • Muscle cells for twisting/turning

  7. Reproduction • Hermaphrodites • Sexual by 2 worms joining, exchanging sperm, and each lay eggs • Internal fertilization • Asexual by fission (organism splits in 2 and each half grows new parts)

  8. Figure 27–3 The Anatomy of a Flatworm Ganglia Eyespot Freshwater flatworms have simple ganglia and nerve cords that run the length of the body. The excretory system consists of a network of tubules connected to flame cells that remove excess water and cell wastes. Head Nervecords Gastrovascularcavity Flatworms use a pharynx to suck food into the gastrovascular cavity. Digested food diffuses from the cavity into other cells of the body. Eyespots in somespecies detect light. Excretorysystem Ovary Testes Mouth Pharynx Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism. Flame cell Excretorytubule

  9. Turbellarians Flukes Tapeworms Classes of Flatworms:

  10. Class Turbellaria: Turbellarians • Free-living • Marine or fresh water • Not Parasitic

  11. Ex. Pseudobiceros gloriosus Tropical free-living flatworm (non-parasitic)

  12. Ex. PlanariaCross-eyed; fresh water free-living flatworm (non-parasitic)

  13. Class Trematoda: Flukes • Parasitic • Infect internal organs of hosts • Blood flukes – travel to intestines of host • Some have Multiple Hosts

  14. Ex. Blood Fluke (not free-living) Parasite that matures in human blood vessels

  15. Schistosoma mansoni (has multiple hosts: Snail=intermediate host Human=primary host)

  16. Figure 27-5 Primary host (human) Flukes mature and reproduce sexually in the blood vessels of human intestines. Embryos are released and passed out with feces. Intermediate host(snail) Adult fluke Human intestine Embryo Ciliated larva Tailed larva After asexualreproduction, newlarvae are releasedfrom the snail into the water. They then infect humans, the primary host, by boring through their skin. Once in the water, embryos develop into swimming larvae that infect an intermediate host (snail).

  17. Class Cestoda: Tapeworms • Parasitic • Lives in intestines • Long and flat • Scolex-head with suckers or hooks • Proglottids-body segments

  18. Cow/Fish (intermediate host) consumes food or water w/ zygotes. • Hatch to larvae and burrow into muscles as cysts (protected) • human eats meat not fully cooked and larvae activated to grow to adult in human intestines.

  19. Roundworms: Phylum Nematoda • Unsegmented • Most are free-living • Digestive tract with two openings – mouth and anus • Pseudocoelom-false body cavity

  20. Feeding • Most are carnivores • Use mouth parts and spines to catch food Hook Worms

  21. Respiration, Circulation, Excretion • Diffusion through body walls

  22. Response • Simple nervous system • Nerves run body length from Ganglia in head • Simple sense organs to detect chemicals from prey or hosts

  23. Movement • Hydrostatic skeleton • Muscles and fluid in the pseudocoelom work together to produce movement

  24. Reproduction • Sexual • Internal fertilization • Separate genders

  25. Human Disease--Parasitic Roundworms • Trichinosis-Causing Worms • Filarial Worms • Ascarid Worms • Hookworms

  26. Trichinella  Trichinosis • Cysts are ingested from eating animal muscle tissue • Females burrow into intestinal wall • Larvae travel to organs via bloodstream and form cysts

  27. Filarial Worms • Live in blood and lymph vessels • Transmitted by mosquitoes • Can block the movement of fluids • Elephantiasis

  28. Ascaris 1. Eggs hatch in intestines 2. Larvae burrow into bloodstream to lungs 3. Travel to air passages, then swallowed 4. Carried to the intestines and mature 5. Eggs released via feces • Spread by eating improperly washed vegetables (foods)

  29. Hookworms • ¼ of the human population infected with hookworms • Eggs hatch outside body and develop in soil • Use sharp toothlike plates and hooks to burrow into skin and enter bloodstream • Travel to lungs and then intestines • Suck blood causing weakness • Don’t walk barefoot outside!!!

  30. Annelids: Phylum Annelida --Segmented worms with a coelom (body cavity) that is lined with mesoderm

  31. Feeding and digestion • Filter feeders to predators • Earthworm • Full Digestive Tract: mouth  pharynxesophaguscropgizzardintestine anus • Crop- store food • Gizzard- grind food

  32. Circulation • Closed system, 2 major blood vessels • Dorsal blood vessel: tail  head (pumps like heart) • Ventral blood vessel: head  tail

  33. Respiration and Excretion • Respiration- • Skin (moist due to mucus secretion) - land • Gills - aquatic • Excretion- • Nephridia - filter out fluid/liquid waste • Anus – solid waste

  34. Movement- • Hydrostatic skeleton • Longitudinal muscles – short and fat • Circular muscles – long and thin • Setae- brushhair-like projections • Reproduction- • Mostly sexual, some hermaphrodites, some separate sexes • Clitellum-thick band secretes mucus ring after 2 worms exchange sperm for fertilization • Mucus ring slips off and forms protective cocoonhatching

  35. Classes of Annelids

  36. Class Oligochaeta: Oligochaetes- Earthworms • Few setae on each segment • Soil or fresh water

  37. Class Hirudinea: Leeches • External parasites • Suck blood and body fluids of host • Medicinal Uses • Reduces swelling and prevents clotting

  38. Class Polychaeta: Polychaetes • Sandworms, bloodworms • Marine • Paired paddle-like appendages w/ setae • Live in coral reefs, sand, mud

  39. What do you think caused this marking? • Worm? • Bacteria? • Virus? • Fungus? • Hickey?

  40. Ringworm • Not caused by a worm! • Fungal infection • Can occur on any part of body • Contact with infected people, animals, soil, etc. • Medically called Tinea

  41. Earthworm Dissection

  42. External View

  43. Internal Structure

  44. Pharynx

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