1. Flatworms, Roundworms, and Rotifers

2. Germ Layers
Layers of cells that originate in the developing embryo and become specific structures
Ectoderm - outer
Mesoderm - middle
Endoderm - inner

3. Body Plans Acoelomate Without a coelom 2 germ layers
Ectoderm and endoderm
Not separated by a cavity
Least complex body plan
Sponges and cnidarians

4. 3 Layer Acoelomate 3 germ layers Endoderm, mesoderm and ectoderm
Not separated by a cavity
Flatworms

5. Pseudocoelomate Pseudocoelom
Cavity formed between mesoderm and endoderm
Roundworms and rotifers

6. Coelomate Cavity developed within the mesoderm Most complex body plan
Mollusks, annelids, arthropods, echinoderms, and chordates

7. Phylum Platyhelminthes - Flatworms
13,000 species
Bilaterally symmetrical
Cephalization
3 classes (Turbellaria, Trematoda, and Cestoda)
Trematodes and cestodes parasitic
Parasites live in or on other organisms (host)

8. Parasitic Flatworms Originated from free living
Some organs modified for parasitism
Lack mouths
Well developed digestive system

9. Hooks or suckers
Tegument- thick covering of cells
Cuticle- nonliving layer secreted by epidermis

10. Class Turbellaria
3000 species
Most marine
Ex. Planaria (fresh water)

11. Planaria External anatomy Anterior end spade shaped
Posterior end tapered
Body covered with cilia

12. Movement Move by undulative motion or
Laying down mucus layer and beating cilia

13. Digestion and Excretion
Scavenger (carrion)
Predator (small prey)

14. Digestion Muscular pharynx extended out of mouth Food sucked in
Passed into intestines (branched)
Nutrients absorbed through intestinal wall or phagocytosis
Undigested food excreted through pharynx and mouth

15. Excretion
Chemical wastes and excess water eliminated by network of ducts (pores and canals)
Contains flame cells
Flame cells enclose a tuft of beating cilia
Cilia moves wastes into the ducts ->
Excretory pores -> out

16. Nervous Control Organized and cephalized
Sense light intensity and direction
Two anterior eyespots (photosensitive cells)
Touch, taste, and smell receptors

17. Two anterior ganglia (clusters of nerves) -> simple brain
Two longitudinal nerves connected by transverse nerves
Capable of simple "learning"
Memory stored chemically

18. Reproduction Hermaphrodites Sexual reproduction
Simultaneous fertilization
Protective encapsulated eggs stick to rock
Hatch 2-3 weeks

19. Asexual (summer)
Attach to rock surface with posterior end
Stretch until they tear into two
Each half regenerates lost parts

20. Class Trematoda 6,000 species
Parasitic - both endoparasites and ectoparasites
Leaf shaped

21. Structure and Reproduction of Flukes
Parasites
1 cm long (oval shaped)
Unciliated tegument

22. 2 sucker mouths (anterior and ventral)
Cling to host
Anterior sucker sucks in blood, cells and fluids of host

23. Nervous and Excretory System
Turbellarian like
Reproduction
Complex reproductive life cycle
Hermaphroditic
Long coiled uterus (stores eggs (10,000+)
Eggs released through genital pore -> larvae

24. Life Cycle
Adults live in sheep liver and gall bladder where they mate and produce eggs
Eggs enter intestines ->
Eliminated with feces ->
Eggs hatch in water ->

25. Larvae invade snail ->
Multiply asexually ->
Leave snail and form cysts ->
Cysts dormant larvae with hard protective covering

26. Ingested by sheep ->
Hatch in digestive tract ->
Bore through intestines into blood ->
Mature and reproduce in liver

27. Schistosomiasis Blood fluke - schistosoma
Infects million people (asia, africa, and so. America)
Around lakes and rivers
Spread via irrigation ditches and reservoirs

28. Adults live in human bloodstream
Eggs lodge in veins, lungs, intestines, bladder, and liver
Block blood vessels
Cause internal bleeding and tissue decay

29. Class Cestoda - Tapeworms
1,500 species
Most parasitic (7 in humans)
Adapted for parasitic life
Tough outer tegument

30. Hooks and suckers
Nervous system extends length of body
Lack sense organs, mouth, and digestive tract

31. Absorb nutrients directly through heavily folded tegument
Knoblike head with hooks and suckers (scolex)
Grows by producing body segments (proglottids)
Oldest proglottids at posterior
Excretory system drains proglottids of waste
Life cycle and reproduction

32. Proglottids contain both male and female reproductive organs
Cross fertilization is typical between individuals or proglottids
After fertilization - proglottids break off and are eliminated with feces

33. Beef tapeworm Cattle eat grass with proglottids and eggs Larvae hatch
Bore through cow's intestine -> blood stream

34. Burrow into muscle tissue and form cysts
Human eats beef (muscle) -> intestine
Cysts wall dissolves and bladder worm released
Develops into an adult beef tapeworm

35. Nematoda and Rotifera Pseudocoelom
Lined on the inside by endoderm and outside by mesoderm
Fluid filled
Contains organs

36. Supports the body
Provides hydrostatic pressure against which muscles can contract
Serves as a storage area for wastes or eggs and sperm

37. Phylum Nematoda - Roundworms
10, ,000 (million) species
Long slender bodies that taper at both ends
Flexible protective cuticle

38. Digestive tract with two opening (1 way)
Anterior mouth
Posterior anus
Sexes distinct in most species
Guinea worm female = 120 cm
Male = 2.5 cm)

39. Excretory wastes collected by system of tubes
Expelled through excretory pore in posterior end
Longitudinal muscles, lack circular muscle -> thrashing motion
Most free living

40. Many plant and animal parasites (enormous economic damage)
Humans host 50 species
More than 1/3 of humans infected

41. Ascaris Found in the intestines of pigs, horses, and humans
Enter body in contaminated food or water
Hatch in intestines
Larvae bore into the blood stream

42. Carried to the lungs and throat
Coughed up, swallowed, returned to intestines
Mature and mate
Block intestines -> death

43. Larvae in lungs cause respiratory illness
Females produce 200,000 eggs/day (contain 27 million eggs)
Shed through genital pore
Exit in hosts feces

44. Ancylostoma and Necator - Hookworms
Ancylostoma - effects 40 million people
Necator - effects 360 million people
Both tropical and semi-tropical
Cutting plates hook into intestinal wall
Feed on hosts blood -> anemia
Attached to intestinal wall
Migrating larvae

45. Travels via blood to lungs and throat where swallowed ->
Mate in intestines ->
Eggs shed in feces ->
Hatch on moist soil ->
Larvae bore through feet or new host

46. Trichinella Causes trichinosis
Undercooked pork contaminated with cysts
Cysts released larvae
Larvae burrow into wall of small intestines

47. Mature into adults ->
Adults produce larvae ->
Pass into blood and form cysts in muscles ->
Causing pain and suffering ->

48. Rotifera 1,750 species Transparent, free swimming and microscopic
Freshwater and marine
Crown of cilia surrounding mouth

49. Cilia sweep food into mouth
Look like rotating wheel
Feed on unicellular algae, bacteria, and protozoa
Moves through pharynx -> mastax
Mastax (muscular organ) chops up food

50. Hydrostatic pressure inside pseudocoelom
Nervous system composed of anterior ganglia and two long longitudinal nerves
Two anterior eye spots