Flatworms and Roundworm

1. Flatworms and Roundworm Chapter 34 688-700 http://www.microscopyu.com/moviegallery/pondscum/index.html http://my.hrw.com/index.jsp

2. Objectives 34.1 • Summarize the distinguishing characteristics of flatworms • Describe the anatomy of a planarian • Compare free-living and parasitic flatworms • Diagram the life cycle of a fluke • Describe the life cycle of a tapeworm

3. P. Platyhelminthesflat worms The P. Platyhelminthes includes organisms called flatworms. Their bodies develop from three germ layers and are more complex than those of sponges, cnidarians, and ctenophores. Flatworms have bilaterally symmetrical bodies, with dorsal and ventral surfaces, right and left sides and anterior and posterior ends.

4. Simple Bilaterally symmetry Flat body Has 3 germ layers Acoelomates Gas exchange in skin (diffusion) Cephalization Free living Parasites (on or inside animals) Only one opening (mouth and anus) Freshwater or marine Structure and Function of Flatworms

5. Structure and Function of Flatworms • 20000 species, 4 classes 1. c. Turbellarira 2. c. Trematoda 3. c. Monagenea 4. c. Cestoda

6. 1. c. TurbellariraA. Digestion and Excretion in Planarians (Dugesia) • 4500 species, Salt water and fresh water - scavengers of decaying plants and animals, small organisms Pharynx (throat) muscular tube that ingests food and sends food to the gastrovascular cavity diffuses to other parts of the body Use flame cells (look like flickering candle flames) along with excretory tubules to remove excess water from hypotonic environments

7. 1. c. TurbellariraB. Neural control in Planarians • More complex than cnidarians • Cerebral ganglia- simple brain, two clusters of nerve cells at the anterior end • Sensory cells transmit to nerves • Eyespot- near the cerebral ganglia, can sense the intensity and direction of light • Can also respond to touch, water currents and chemical in the environment

8. 1. c. TurbellariraC. Reproduction in Planarians • Hermaphrodites • Sexual reproduction- they simultaneously fetilize each other • Eggs are in a capsules and stick to rocks (3wks to hatch) • Can also reproduce asexually (summer) • The worm will split in two- fission • Worm can regenerate tail

12. c. Trematoda and c. Monagenea • Parasitic flukes (leaf-shaped flatworms) • Parasite • Endoparasites- live inside organism (blood, intestines, lungs, liver, other organs) • Exctoparasites- external surfaces (fish and frogs)

14. c. Trematoda and c. Monageneastructure of flukes • Anterior suckers and ventral sucker • Simple nervous system • Tegument- outer covering made up of proteins and carbohydrates that is a defense mechanism • Protects against digestive enzymes

15. c. Trematoda and c. MonageneaReproduction and life cycle flukes • Hermaphroditic • Fertilized eggs are store in uterus • May release tens of thousands at one time • Have more than one host

17. Schistosoma • Primary host- adult parasite gets its nourishment, sexual reproduction occurs (humans blood vessels) • Excreted in wastes fresh water system • Becomes a ciliated larva and will attach a snail will mature and develop a tail  burrow into humans in water • If eggs don’t leave---- can be fatal • 200million people world wide http://www.dpd.cdc.gov/DPDx/HTML/Opisthorchiasis.asp?body=Frames/M-R/Opisthorchiasis/body_Opisthorchiasis_page1.htm

18. Schistosoma

19. c. Cestoda • 5000 species of tapeworms • Intestines of almost all vertebrates • Eating raw or undercooked food containing eggs or larvae • May cause digestion problems, weight loss, lack of energy, anemia, decrees in red blood cells

21. c. Cestoda- Structure of Tapeworm • Also have tegument • Scolex- hooks and suckers to host • Proglottids- long series of body sections • Similar nervous/ excretory system to other flatworms • Lack eyespots/ other light sensing organs • No mouth, gastrovascular cavity, digestive organs • Get nutrients by absorbing directly from host digestive track

22. c. Cestoda- Reproduction and life cycle of Tapeworm • Hermaphrodites • 1000000 or more eggs in the proglottid Tanenia saginatus- Has two host (human and cow) Cysts- dormant larvae

23. 34.2 Objectives • Describe the body plan of a nematode • Outline the relationship between humans and parasitic roundworms • Describe the anatomy of a rotifer

24. P. Nematoda • Members of the phyla Nematoda are bilaterally symmetrical bodies that contain a fluid-filled space. This space holds the internal organs and serves as a storage area for eggs and sperm. It also supports the body and provides a structure against which the muscles can contract.

25. P. Nematoda (roundworms) • 15000 knows species, estimated 500,000 • Long slender bodies that taper at ends • Pseudocoelomates • 1mm to 120 cm • Have a complete digestive tract (mouth-gut – anus) • Separate sexes • Fresh and salt water, land • Can be parasites of plants and animals • http://www.microscopyu.com/moviegallery/pondscum/nematode/index.html

26. Ascaris • Live in pig, horse, humans intestines • Feed on food from host • Can block hosts intestines • 30cm long (1ft) • 200,000 eggs every day, leave body in feces • Can live in soil for years • Contaminated food and water • Larvae bore into bloodstream lungs and throat  to intestines • Colonoscopy Demonstrating a Moving Worm http://www.youtube.com/watch?v=HOaZCkA8Zvk

27. Phylum Nematoda Ascaris worms

30. Hookworms • Parasite (tropical and subtropical regions) • Mouth has cutting plates hook on intestinal wall • Can cause anemia • Can cause slow mental development in children • Larva live in soil  boring through host’s feet  travel to intestines • Infect 1 billion people a year

31. Trichinella • Infect human, pigs and other mammals • Eating undercooked meat • Live in walls of host intestines • Larvae are in cysts • Causes Trichinosis, muscle pain and stiffness • Cook and freeze at high temps to kill worms

32. Other Parasitic roundwormspinworm, Enterobius • Most common 50% in some areas • Not serious • 5-10mm, look like threads • Live in lower region of intestines/ anus • At night female exists and lays eggs • Person scratches during sleep can be passed on to other persons • Eggs must be ingested and will hatch in intestine

33. Other Parasitic roundworms Filarial worms- • Infect over 250 million in tropical countries • Live in lymphatic system • 100mm or 4in • Enter blood passed by mosquitoes • Causes swollen limbs and the skin hardens and thickens  elephantiasis Toxocara or T. cati- heart worms of dogs and cats

36. Ascaris Dissection • http://www.youtube.com/watch?v=_ybbnPj0t9Y&feature=PlayList&p=E0DC6AAA94AFE60F&playnext_from=PL&playnext=1&index=8

37. Annelids Chapter 35 704-719 http://www.microscopyu.com/moviegallery/pondscum/index.html http://my.hrw.com/index.jsp

38. 35.2 objectives • Identify the structures that provide the basis for dividing annelids into three classes • List the advantages of body segmentation • Describe the structural adaptation of earthworms • Compare the three classes of annelids

39. P. Annelida Colorful feather-dusters worms, common earthworms, and bloodsucking leaches are all members of the p. Annelida, a term that means “little rings.” The name refers to the many body segments that make an annelid look as if it is composed of a series of rings.

40. Characteristics of annelids • 15,000 species • Bilaterally symmetrical • Segmented worms • True coelom • One segment gets injured – can still surrive • External bristles – setae • Parapodis- fleshy protrusions 3 classes • C. Oligochaeta 2. C. Polycheaeta 3. C. Hirudinea

41. Class Oligochaeta- few bristles, few setae • Live in soil or fresh water • No parapodia • ? How can this animal burrow 1. Structure and movement - 100 segments - contract circular muscles to move

43. Class Oligochaeta cont 2. Feeding and Digestion • Ingest soil as burrow  mouth  pharynx  to esophagus crop  gizzard  absorption of nutrients (typhlosole) • Maintaining fertility of soil (decompose leaves), air to roots of plants, loosen soil 3. Circulation • Closed system • 5 pairs of aortic arches

44. Class Oligochaeta cont 4. Respiration and excretion • Diffuse directly through skin (gas exchange) • Need to keep skin moist (cuticle/ mucus) • Nephridia- excretory tubules 5. Neural control • Chain of ganglia connected by a ventral nerve cord • Anterior end- cerebral ganglia or brain • Respond to light, touch, chemicals, temp., moist

45. Class Oligochaeta cont 6. Reproduction • Hermaphrodites • Can not fertilize its own egg • Ventral surfaces must join anterior ends pointing in opposite direction, held together by setae and film of mucus secreted by the clitellum • Sperm is injected into mucus pass to seminal receptacle • Fertilization occurs inside 2-3 wks to hatch

47. C. Polycheaeta- many bristles • Many bristles help them move • 2/3 of all annelids • Antennae • Specialized mouth parts • Trochophore stage • Marine habitats • Free swimming • Some eat sediments in ocean

48. C. Hirudinea • Smallest of all annelids • 500 species of leeeches • Fresh water • Mosit vegetation • No setae or parapodia • Sucker • Secret an anaesthetic • Can ingest 10 times own weight in blood

49. OK…to end to a peaceful note, these, too, are segmented worms….