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)

4. Feeding
Carnivore
Scavenger
Parasitic
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

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

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

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

9. 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)

10. 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
Nerve cords
Gastrovascular cavity
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 some species detect light.
Excretory system
Ovary
Testes
Mouth
Pharynx
Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism.
Flame cell
Excretory tubule

11. Turbellarians
Flukes
Tapeworms
Classes of Flatworms:

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

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

15. Ex. Planaria Cross-eyed; fresh water free-living flatworm (non-parasitic)

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

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

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

19. 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 asexual reproduction, new larvae are released from 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).

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

21. 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.

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

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

24. Respiration, Circulation, Excretion
Diffusion through body walls

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

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

27. Reproduction
Sexual
Internal fertilization
Separate genders

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

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

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

31. 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)

33. 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!!!

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

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

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

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

39. Movement- Reproduction- Hydrostatic skeleton
Longitudinal muscles – short and fat
Circular muscles – long and thin
Setae- brush hair-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

41. Classes of Annelids

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

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

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

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

46. 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

47. Earthworm Dissection

48. External View

49. Internal Structure

50. Pharynx

51. Aortic Arches

52. Seminal Vesicle

53. Seminal Receptacle

54. Septum

55. Crop

56. Gizzard

57. Intestine

58. Ventral Nerve Cord

59. Dorsal Blood Vessel