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

2. Section 1 Platyhelminthes
Chapter 34
Objectives
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. Structure and Function of Flatworms
Section 1 Platyhelminthes
Chapter 34
Structure and Function of Flatworms
The phylum _____________________ 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 _______________ with dorsoventrally flattened bodies.
They exhibit ___________________.

4. 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.
_______________ have a spade-shaped anterior end and a tapered posterior end.

5. Class Turbellaria, continued
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 _____________.
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.

6. Class Turbellaria, continued
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 _______________ serve as a simple brain.
A planarian’s nervous system gives it the ability to learn.
Planarians sense light with _______________.
Other sensory cells respond to touch, water currents, and chemicals in the environment.

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

8. Section 1 Platyhelminthes
Chapter 34
Planarian

9. Exploration of a Flatworm
Section 1 Platyhelminthes
Chapter 34
Exploration of a Flatworm

10. Development of Flatworm Embryo
Section 1 Platyhelminthes
Chapter 34
Development of Flatworm Embryo

11. Classes Trematoda and Monogenea
Section 1 Platyhelminthes
Chapter 34
Classes Trematoda and Monogenea
The classes Trematoda and Monogenea consist of parasitic ______________.
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 _________________.

12. Classes Trematoda and Monogenea, continued
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 __________ as a primary hosts and __________ as intermediate hosts. They can cause schistosomiasis.

13. Life Cycle of Schistosoma
Section 1 Platyhelminthes
Chapter 34
Life Cycle of Schistosoma

14. Section 1 Platyhelminthes
Chapter 34
Class Cestoda
About 5,000 species of ______________ 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 ___________.
The body is a series of many sections called _________________.
Tapeworms have no light-sensing organs, no mouth, no gastrovascular cavity, and no digestive organs.

15. Class Cestoda, continued
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 ___________ in the muscle tissue of the cow.

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

17. Objectives Describe the body plan of a nematode.
Section 2 Nematoda and Rotifera
Chapter 34
Objectives
Describe the body plan of a nematode.
Outline the relationship between humans and parasitic roundworms.
Describe the anatomy of a rotifer.

18. Phylum Nematoda Chapter 34
Section 2 Nematoda and Rotifera
Chapter 34
Phylum Nematoda
The phylum Nematoda is made up of _________________ with long, slender bodies that taper at both ends.
Roundworms are among several phyla of __________________________.
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.

19. Phylum Nematoda, continued
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 ___________ people worldwide.

20. Phylum Nematoda, continued
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.
________________infect many people in tropical countries. The most dangerous ones infect the lymphatic system and may cause ___________________.

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

22. Phylum Rotifera Chapter 34
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 ___________.
The digestive, reproductive, and excretory systems empty into the ______________.
Some species reproduce by ____________________.

23. 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

24. Multiple Choice, continued
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

25. Multiple Choice, continued
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

26. Multiple Choice, continued
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

27. Multiple Choice, continued
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

28. Multiple Choice, continued
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

29. Multiple Choice, continued
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.

30. Multiple Choice, continued
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.

31. Multiple Choice, continued
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.

32. Multiple Choice, continued
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

33. Multiple Choice, continued
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

34. Multiple Choice, continued
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

35. Multiple Choice, continued
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

36. Multiple Choice, continued
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

37. Multiple Choice, continued
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

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

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

40. Multiple Choice, continued
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.

41. Multiple Choice, continued
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

42. Multiple Choice, continued
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

43. Chapter 34
Standardized Test Prep
Short Response
Planarians and rotifers eliminate water through a network of excretory structures that run the length of the body. Explain why the excretory structures in planarians and rotifers are called flame cells.

44. Short Response, continued
Chapter 34
Standardized Test Prep
Short Response, continued
Planarians and rotifers eliminate water through a network of excretory structures that run the length of the body. Explain why the excretory structures in planarians and rotifers are called flame cells. Answer: The beating of the cilia in flame cells draws water from surrounding tissue. It is the motion of the cilia that resembles the flickering of a flame.

45. Chapter 34
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information below. Parasitic flatworms have life cycles that include primary and intermediate hosts. Part A Distinguish between primary and intermediate hosts in flatworms. Part B Sequence the life cycle of a beef tapeworm. Identify the primary and intermediate hosts.

46. Extended Response, continued
Chapter 34
Standardized Test Prep
Extended Response, continued
Answer:
Part A Primary hosts nourish the adult parasite. Intermediate hosts nourish the larval parasite.
Part B: Adult tapeworms live in the intestines of the primary host, humans. Mature proglotids are shed in the feces and release eggs. Eggs ingested by cows, the intermediate host, develop into larvae, burrow to muscle tissue, and develop into adults when a human eats infected,undercooked beef.