End Show Slide 1 of 41 Copyright Pearson Prentice Hall Biology

End Show Slide 2 of 41 Copyright Pearson Prentice Hall 27–1 Flatworms

End Show 27–1 Flatworms Slide 3 of 41 Copyright Pearson Prentice Hall What Is a Flatworm? Flatworms are soft, flattened worms that have tissues and internal organ systems. They are the simplest animals to have three embryonic germ layers, bilateral symmetry, and cephalization.

End Show 27–1 Flatworms Slide 4 of 41 Copyright Pearson Prentice Hall What Is a Flatworm? Flatworms are acoelomates, which means they have no coelom. A coelom is a fluid-filled body cavity that is lined with tissue derived from mesoderm. The digestive cavity is the only body cavity in a flatworm. Flatworms have bilateral symmetry.

End Show 27–1 Flatworms Slide 5 of 41 Copyright Pearson Prentice Hall What Is a Flatworm? Three germ layers of a flatworm

End Show 27–1 Flatworms Slide 6 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms All flatworms rely on diffusion for respiration, excretion, and circulation.

End Show 27–1 Flatworms Slide 7 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Most parasitic worms do not need a complex digestive system. They obtain nutrients from foods that have already been digested by their host.

End Show 27–1 Flatworms Slide 8 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Digestive Structures of a Planarian Mouth Pharynx Digestive cavity Head Eyespot

End Show 27–1 Flatworms Slide 9 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Testes Ovary Ganglia Nerve cords Excretory system Flame cell Excretory tubule Excretory, Nervous, and Reproductive Structures of a Planarian

End Show 27–1 Flatworms Slide 10 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Movement Free-living flatworms move in two ways. Cilia on their epidermal cells help them glide through the water and over the bottom of a stream or pond. Muscle cells controlled by the nervous system allow them to twist and turn.

End Show 27–1 Flatworms Slide 11 of 41 Copyright Pearson Prentice Hall Groups of Flatworms The three main groups of flatworms are turbellarians flukes tapeworms Most turbellarians are free-living. Most other flatworm species are parasites.

End Show 27–1 Flatworms Slide 12 of 41 Copyright Pearson Prentice Hall Groups of Flatworms Turbellarians Turbellarians are free-living flatworms. Most live in marine or fresh water. Most species live in the sand or mud under stones and shells.

End Show 27–1 Flatworms Slide 13 of 41 Copyright Pearson Prentice Hall Groups of Flatworms Flukes Flukes are parasitic flatworms. Most flukes infect the internal organs of their host.

End Show 27–1 Flatworms Slide 14 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Life Cycle of a Blood Fluke

End Show 27–1 Flatworms Slide 15 of 41 White Tail Deer Liver Fluke Copyright Pearson Prentice Hall

End Show 27–1 Flatworms Slide 16 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Tapeworms Tapeworms are long, flat, parasitic worms that are adapted to life inside the intestines of their hosts.

End Show 27–1 Flatworms Slide 17 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Structures of a Tapeworm Mature proglottids Zygotes Testes Ovary Uterus Young proglottids Scolex

End Show 27–1 Flatworms Slide 18 of 41 Copyright Pearson Prentice Hall Form and Function in Flatworms Proglottids are the segments that make up most of the worm's body. Mature proglottids contain both male and female reproductive organs.

End Show - or - Continue to: Click to Launch: Slide 19 of 41 Copyright Pearson Prentice Hall 27–1

End Show Slide 20 of 41 Copyright Pearson Prentice Hall 27–1 Flatworms are the simplest animals to have a.two germ layers. b.bilateral symmetry. c.radial symmetry. d.two openings in the digestive system.

End Show Slide 21 of 41 Copyright Pearson Prentice Hall 27–1 An individual that has both male and female reproductive organs is known as a a.turbellarian. b.proglottid. c.hermaphrodite. d.parasite.

End Show Slide 22 of 41 Copyright Pearson Prentice Hall 27–1 The function of flame cells in flatworms is to a.digest food and move it to various parts of the body. b.detect the presence of chemicals in the surroundings. c.remove excess water and metabolic wastes d.move reproductive cells into position for fertilization.

End Show Slide 23 of 41 Copyright Pearson Prentice Hall 27–1 A flatworm that lacks a digestive tract is the a.planarian. b.free-living flatworm. c.tapeworm. d.fluke.

End Show Slide 24 of 41 Copyright Pearson Prentice Hall 27–1 Turbellarians differ from most other flatworms because they a.live freely on land. b.live freely in fresh and salt water. c.are marine parasites. d.are land-dwelling parasites.

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