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2. Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

3. Flatworms, Roundworms, and Rotifers Chapter 34 Table of Contents Section 1 Platyhelminthes Section 2 Nematoda and Rotifera

4. Section 1 Platyhelminthes Chapter 34 Objectives • Summarizethe distinguishing characteristics of flatworms. • Describethe anatomy of a planarian. • Comparefree-living and parasitic flatworms. • Diagram the life cycle of a fluke. • Describethe life cycle of a tapeworm.

5. Section 1 Platyhelminthes Chapter 34 Structure and Function of Flatworms • The phylum Platyhelminthes includes organisms called flatworms. • They are more complex than sponges but are the simplest animals with bilateral symmetry. • Their bodies develop from three germ layers: • ectoderm • mesoderm • endoderm • They are acoelomates with dorsoventrally flattened bodies. • They exhibit cephalization. • The classification of Platyhelminthes has undergone many recent changes.

6. Section 1 Platyhelminthes Chapter 34 Characteristics of Flatworms

7. Section 1 Platyhelminthes Chapter 34 Class Turbellaria • The majority of species in the class Turbellaria live in the ocean. • The most familiar turbellarians are the freshwater planarians of the genus Dugesia. • Planarians have a spade-shaped anterior end and a tapered posterior end.

8. Section 1 Platyhelminthes Chapter 34 Class Turbellaria, continued Digestion and Excretion in Planarians • Planarians feed on decaying plant or animal matter and smaller organisms. • Food is ingested through the pharynx. • Planarians eliminate excess water through a network of excretory tubules. • Each tubule is connected to several flame cells. • The water is transported through the tubules and excreted from pores on the body surface.

9. Section 1 Platyhelminthes Chapter 34 Class Turbellaria, continued Neural Control in Planarians • The planarian nervous system is more complex than the nerve net of cnidarians. • The cerebral ganglia serve as a simple brain. • A planarian’s nervous system gives it the ability to learn. • Planarians sense light with eyespots. • Other sensory cells respond to touch, water currents, and chemicals in the environment.

10. Section 1 Platyhelminthes Chapter 34 Class Turbellaria, continued Reproduction in Planarians • Planarians are hermaphrodites that can reproduce sexually or asexually. • Their eggs are laid in capsules. • During asexual reproduction, their body undergoes fission and the two halves regenerate missing parts.

11. Section 1 Platyhelminthes Chapter 34 Planarian

12. Section 1 Platyhelminthes Chapter 34 Anatomy of a Planarian

13. Section 1 Platyhelminthes Chapter 34 Exploration of a Flatworm

14. Section 1 Platyhelminthes Chapter 34 Development of Flatworm Embryo

15. Section 1 Platyhelminthes Chapter 34 Classes Trematoda and Monogenea • The classes Trematoda and Monogenea consist of parasitic flukes. • Some are endoparasites; others are ectoparasites. Structure of Flukes • A fluke clings to the tissues of its host by an anterior sucker and a ventral sucker. • A fluke’s nervous system is similar to a planarian’s, but simpler. • The external surface of a fluke is covered by a protective layer called the tegument.

16. Section 1 Platyhelminthes Chapter 34 Tegument

17. Section 1 Platyhelminthes Chapter 34 Classes Trematoda and Monogenea, continued Reproduction and Life Cycle of Flukes • Most flukes have highly developed reproductive systems and are hermaphroditic. • Fertilized eggs are stored in a fluke’s uterus until they are ready to be released. • Flukes have complicated life cycles that involve more than one host species. • For example, the trematode blood flukes of the genus Schistosoma use humans as a primary hosts and snails as intermediate hosts. They can cause schistosomiasis.

18. Section 1 Platyhelminthes Chapter 34 Life Cycle of Schistosoma

19. Section 1 Platyhelminthes Chapter 34 Life Cycle of Flukes

20. Section 1 Platyhelminthes Chapter 34 Class Cestoda • About 5,000 species of tapeworms make up the class Cestoda. • Tapeworms can live in the intestines of almost all vertebrates. Structure of Tapeworms • Tapeworms are surrounded by a tegument. • They attach to the host with a scolex. • The body is a series of many sections called proglottids. • Tapeworms have no light-sensing organs, no mouth, no gastrovascular cavity, and no digestive organs.

21. Section 1 Platyhelminthes Chapter 34 Anatomy of a Tapeworm

22. Section 1 Platyhelminthes Chapter 34 Class Cestoda, continued Reproduction and Life Cycle of Tapeworms • Nearly all tapeworms are hermaphrodites. Each proglottid contains male and female reproductive organs and little else. • New proglottids are added to the front of the tapeworm. Older proglottids grow, mature, and begin producing eggs. • Eggs in one proglottid are usually fertilized by sperm from a different proglottid, possibly a different individual. • An example is the beef tapeworm, Taenia saginatus. Its primary host is a human and its intermediate host is a cow. Its larvae form cysts in the muscle tissue of the cow.

23. Section 1 Platyhelminthes Chapter 34 Life Cycle of Beef Tapeworm

24. Section 1 Platyhelminthes Chapter 34 Life Cycle of Tapeworms

25. Section 2 Nematoda and Rotifera Chapter 34 Objectives • Describethe body plan of a nematode. • Outlinethe relationship between humans and parasitic roundworms. • Describethe anatomy of a rotifer.

26. Section 2 Nematoda and Rotifera Chapter 34 Phylum Nematoda • The phylum Nematoda is made up of roundworms with long, slender bodies that taper at both ends. • Roundworms are among several phyla of pseudocoelomates. • Roundworms have a digestive tract with two openings. • Most roundworms have separate sexes and are covered by a protective cuticle. • Most species are free-living; some are parasites.

27. Section 2 Nematoda and Rotifera Chapter 34 Phylum Nematoda, continued Ascaris • The genus Ascaris infects pigs, horses, and humans. • The eggs enter hosts through contaminated food or water, develop into larvae in the intestines, and can infect the lungs. • The eggs are spread in the hosts’ feces. Hookworms • Hookworms are intestinal parasites that feed on blood. • The eggs produce larvae in soil, and the larvae enter hosts through the feet. • Hookworms infect about one billion people worldwide.

28. Section 2 Nematoda and Rotifera Chapter 34 Phylum Nematoda, continued Trichinella • The genus Trichinella infects humans and other mammals. • Adults live in intestines and larvae form cysts in muscles. • People usually become infected from undercooked pork. • Infection causes the disease trichinosis. Other Parasitic Roundworms • Pinworms, genus Enterobius, are common parasites of humans. They do not cause any serious disease. • Filarialworms infect many people in tropical countries. The most dangerous ones infect the lymphatic system and may cause elephantiasis.

29. Section 2 Nematoda and Rotifera Chapter 34 Exploration of a Roundworm

30. Section 2 Nematoda and Rotifera Chapter 34 Phylum Rotifera • Members of the phylum Rotifera are called rotifers. • Most rotifers are tiny, transparent, free-living animals that live in fresh water. • Some can survive without water for long periods. • Although tiny, they are truly multicellular and have specialized organ systems. • They use the crown of cilia around their mouth to sweep food into the mastax. • The digestive, reproductive, and excretory systems empty into the cloaca. • Some species reproduce by parthenogenesis.

31. Chapter 34 Standardized Test Prep Multiple Choice 1. What does a planarian use its pharynx for? A. feeding B. movement C. reproduction D. to respond to light

32. Chapter 34 Standardized Test Prep Multiple Choice, continued 1. What does a planarian use its pharynx for? A. feeding B. movement C. reproduction D. to respond to light

33. Chapter 34 Standardized Test Prep Multiple Choice, continued 2. Where do blood flukes of the genus Schistosoma reproduce asexually? F. in water G. inside a snail H. inside a cow’s intestine J. inside a human’s blood vessels

34. Chapter 34 Standardized Test Prep Multiple Choice, continued 2. Where do blood flukes of the genus Schistosoma reproduce asexually? F. in water G. inside a snail H. inside a cow’s intestine J. inside a human’s blood vessels

35. Chapter 34 Standardized Test Prep Multiple Choice, continued 3. What does a tapeworm use its scolex for? A. to reproduce B. to attach itself to its host C. to eliminate excess water D. to force food into its mouth

36. Chapter 34 Standardized Test Prep Multiple Choice, continued 3. What does a tapeworm use its scolex for? A. to reproduce B. to attach itself to its host C. to eliminate excess water D. to force food into its mouth

37. Chapter 34 Standardized Test Prep Multiple Choice, continued 4. Which of the following is true of most rotifers? F. They are parasitic. G. They live in the soil. H. They feed with the help of cilia. J. They have a gastrovascular cavity.

38. Chapter 34 Standardized Test Prep Multiple Choice, continued 4. Which of the following is true of most rotifers? F. They are parasitic. G. They live in the soil. H. They feed with the help of cilia. J. They have a gastrovascular cavity.

39. Chapter 34 Standardized Test Prep Multiple Choice, continued The figure below shows the internal structure of a planarian of the genus Dugesia. Use the figure to answer the questions that follow.

40. Chapter 34 Standardized Test Prep Multiple Choice, continued 5. What type of animal is shown in the figure? A. flatworm B. tapeworm C. roundworm D. rotifer

41. Chapter 34 Standardized Test Prep Multiple Choice, continued 5. What type of animal is shown in the figure? A. flatworm B. tapeworm C. roundworm D. rotifer

42. Chapter 34 Standardized Test Prep Multiple Choice, continued 6. What is the structure labeled X? F. the brain G. the mouth H. an eyespot J. a nerve cord

43. Chapter 34 Standardized Test Prep Multiple Choice, continued 6. What is the structure labeled X? F. the brain G. the mouth H. an eyespot J. a nerve cord

44. Chapter 34 Standardized Test Prep Multiple Choice, continued 7. What is the structure labeled Y? A. the mouth B. a flame cell C. an eyespot D. the gastrovascular cavity

45. Chapter 34 Standardized Test Prep Multiple Choice, continued 7. What is the structure labeled Y? A. the mouth B. a flame cell C. an eyespot D. the gastrovascular cavity

46. Chapter 34 Standardized Test Prep Multiple Choice, continued 8. fluke : schistosomiasis :: filarial worm : F. trichinosis G. elephantiasis H. encysted meat J. swimmer’s itch

47. Chapter 34 Standardized Test Prep Multiple Choice, continued 8. fluke : schistosomiasis :: filarial worm : F. trichinosis G. elephantiasis H. encysted meat J. swimmer’s itch

48. Chapter 34 Standardized Test Prep Multiple Choice, continued The figure below shows the internal structure of a rotifer. Use the figure to answer the question that follows.

49. Chapter 34 Standardized Test Prep Multiple Choice, continued 9. Which structures are involved in excretion? A. K and L B. L and O C. M and N D. M and P

50. Chapter 34 Standardized Test Prep Multiple Choice, continued 9. Which structures are involved in excretion? A. K and L B. L and O C. M and N D. M and P