1 / 28

Table of Contents

Flatworms, Roundworms, and Rotifers. Chapter 34. Table of Contents. Section 1 Platyhelminthes Section 2 Nematoda and Rotifera. Section 1 Platyhelminthes. Chapter 34. Objectives. Summarize the distinguishing characteristics of flatworms. Describe the anatomy of a planarian.

akira
Télécharger la présentation

Table of Contents

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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 • 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.

  3. 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.

  4. Section 1 Platyhelminthes Chapter 34 Characteristics of Flatworms Click below to watch the Visual Concept. Visual Concept

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Section 1 Platyhelminthes Chapter 34 Planarian

  10. Section 1 Platyhelminthes Chapter 34 Anatomy of a Planarian Click below to watch the Visual Concept. Visual Concept

  11. Section 1 Platyhelminthes Chapter 34 Exploration of a Flatworm

  12. Section 1 Platyhelminthes Chapter 34 Development of Flatworm Embryo

  13. 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.

  14. Section 1 Platyhelminthes Chapter 34 Tegument

  15. 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.

  16. Section 1 Platyhelminthes Chapter 34 Life Cycle of Schistosoma

  17. Section 1 Platyhelminthes Chapter 34 Life Cycle of Flukes Click below to watch the Visual Concept. Visual Concept

  18. 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.

  19. Section 1 Platyhelminthes Chapter 34 Anatomy of a Tapeworm Click below to watch the Visual Concept. Visual Concept

  20. 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.

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

  22. Section 1 Platyhelminthes Chapter 34 Life Cycle of Tapeworms Click below to watch the Visual Concept. Visual Concept

  23. 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.

  24. 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.

  25. 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.

  26. 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.

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

  28. 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.

More Related