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Table of Contents – pages iii Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit.

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Presentation on theme: "Table of Contents – pages iii Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit."— Presentation transcript:

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3 Table of Contents – pages iii Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit 6: Viruses, Bacteria, Protists, and Fungi Unit 7: Plants Unit 8: InvertebratesInvertebrates Unit 9: Vertebrates Unit 10: The Human Body

4 Table of Contents – pages vii-xiii Unit 1: What is Biology? Chapter 1: Biology: The Study of Life Unit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and Conservation Unit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell

5 Table of Contents – pages vii-xiii Unit 4: Genetics Chapter 10: Mendel and Meiosis Chapter 11: DNA and Genes Chapter 12: Patterns of Heredity and Human Genetics Chapter 13: Genetic Technology Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: The Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity

6 Table of Contents – pages vii-xiii Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18: Viruses and Bacteria Chapter 19: Protists Chapter 20: Fungi Unit 7: Plants Chapter 21: What Is a Plant? Chapter 22: The Diversity of Plants Chapter 23: Plant Structure and Function Chapter 24: Reproduction in Plants

7 Table of Contents – pages vii-xiii Unit 8: InvertebratesInvertebrates Chapter 25: What Is an Animal? Chapter 26: Sponges, Cnidarians, Flatworms, and RoundwormsSponges, Cnidarians, Flatworms, and Roundworms Chapter 27: Mollusks and Segmented Worms Chapter 28: Arthropods Chapter 29: Echinoderms and Invertebrate Chordates

8 Table of Contents – pages vii-xiii Unit 9: Vertebrates Chapter 30: Fishes and Amphibians Chapter 31: Reptiles and Birds Chapter 32: Mammals Chapter 33: Animal Behavior Unit 10: The Human Body Chapter 34: Protection, Support, and Locomotion Chapter 35: The Digestive and Endocrine Systems Chapter 36: The Nervous System Chapter 37: Respiration, Circulation, and Excretion Chapter 38: Reproduction and Development Chapter 39: Immunity from Disease

9 Unit Overview – pages 670-671 Sponges, Cnidarians, Flatworms, and Roundworms What Is an Animal? Sponges, Cnidarians, Flatworms, and Roundworms Mollusks and Segmented Worms Arthropods Echinoderms and Invertebrate Chordates

10 Chapter Contents – page xi Chapter 26 Sponges, Cnidarians, Flatworms, and RoundwormsSponges, Cnidarians, Flatworms, and Roundworms 26.1: SpongesSponges 26.1: Section CheckSection Check 26.2: CnidariansCnidarians 26.2: Section CheckSection Check 26.3: FlatwormsFlatworms 26.3: Section CheckSection Check 26.4: RoundwormsRoundworms 26.4: Section CheckSection Check Chapter 26 SummarySummary Chapter 26 AssessmentAssessment

11 Chapter Intro-page 692 What You’ll Learn You will identify and compare and contrast the characteristics of sponges, cnidarians, flatworms, and roundworms. You will describe and evaluate the significance of sponge, cnidarian, flatworm, and roundworm adaptations.

12 26.1 Section Objectives – page 693 Relate the sessile life of sponges to their food-gathering adaptations. Section Objectives: Describe the reproductive adaptations of sponges.

13 Section 26.1 Summary – pages 693-697 Sponges are asymmetrical aquatic animals that have a variety of colors, shapes, and sizes. Many are bright shades of red, orange, yellow, and green. What is a sponge?

14 Section 26.1 Summary – pages 693-697 What is a sponge? Although sponges do not resemble more familiar animals, they carry on the same life processes as all animals.

15 Section 26.1 Summary – pages 693-697 Sponges are classified in the invertebrate phylum Porifera, which means “pore bearer.” Most live in marine biomes, but about 150 species can be found in freshwater environments. Sponges are pore-bearers

16 Section 26.1 Summary – pages 693-697 Sponges are mainly sessile organisms. Because most adult sponges can’t travel in search of food, they get their food by a process called filter feeding. Sponges are pore-bearers Water out Central cavity Water in

17 Section 26.1 Summary – pages 693-697 Sponges are pore-bearers Filter feeding is a method in which an organism feeds by filtering small particles of food from water that pass by or through some part of the organism. Water out Central cavity Water in

18 Section 26.1 Summary – pages 693-697 A Sponge Osculum Pore cell Epithelial-like cells Collar cells Amoebocyte Direction of water flow through pores Spicules

19 Section 26.1 Summary – pages 693-697 Cell organization in sponges For some sponge species, if you took a living sponge and put it through a sieve, not only would the sponge’s cells be alive and separated out, but these cells would come together to form new sponges. It can take several weeks for the sponge’s cells to reorganize themselves.

20 Section 26.1 Summary – pages 693-697 Cell organization in sponges Many biologists hypothesize that sponges evolved directly from colonial, flagellated protists, such as Volvox. Volvox

21 Section 26.1 Summary – pages 693-697 Cell organization in sponges More importantly, sponges exhibit a major step in the evolution of animals—the change from unicellular life to a division of labor among groups of organized cells.

22 Section 26.1 Summary – pages 693-697 Reproduction in sponges Sponges can reproduce asexually and sexually. Depending on the species, asexual reproduction can be by budding, fragmentation, or the formation of gemmules.

23 Section 26.1 Summary – pages 693-697 Reproduction in sponges An external growth, called a bud, can form on a sponge. If a bud drops off, it can float away, settle, and grow into a sponge. Sometimes, buds do not break off. When this occurs, a colony of sponges forms. Often, fragments of a sponge break off and grow into new sponges.

24 Section 26.1 Summary – pages 693-697 Reproduction in sponges Some freshwater sponges produce seedlike particles, called gemmules, in the fall when waters cool. The adult sponges die over the winter, but the gemmules survive and grow into new sponges in the spring when waters warm.

25 Section 26.1 Summary – pages 693-697 Reproduction in sponges Most sponges reproduce sexually. Some sponges have separate sexes, but most sponges are hermaphrodites. A hermaphrodite (hur MAF ruh dite) is an animal that can produce both eggs and sperm.

26 Section 26.1 Summary – pages 693-697 Reproduction in sponges Eggs and sperm form from amoebocytes. During reproduction, sperm released from one sponge can be carried by water currents to another sponge, where fertilization can occur.

27 Section 26.1 Summary – pages 693-697 Reproduction in sponges Fertilization in sponges may be either external or internal. A few sponges have external fertilization—fertilization that occurs outside the animal’s body. Most sponges have internal fertilization, in which eggs inside the animal’s body are fertilized by sperm carried into the sponge with water.

28 Section 26.1 Summary – pages 693-697 Sperm cells Larvae Egg cell Flagella New sponge

29 Section 26.1 Summary – pages 693-697 Reproduction in sponges In sponges, the collar cells collect and transfer sperm to amoebocytes. The amoebocytes then transport the sperm to ripe eggs.

30 Section 26.1 Summary – pages 693-697 Support and defense systems in sponges Sponges are soft-bodied invertebrates, that can be found at depths of about 8500 m. Their internal structure gives them support and can help protect them from predators.

31 Section 26.1 Summary – pages 693-697 Support and defense systems in sponges Some sponges have sharp, hard spicules located between the cell layers. Spicules may be made of glasslike material or of calcium carbonate. Spicules

32 Section 26.1 Summary – pages 693-697 Support and defense systems in sponges Other sponges have an internal framework made of silica or of spongin, a fibrous protein-like material. Sponges can be classified according to the shape and makeup of their spicules and/or frameworks.

33 Section 26.1 Summary – pages 693-697 Support and defense systems in sponges Besides sharp spicules, some sponges may have other methods of defense. Some sponges contain chemicals that are toxic to fishes and to other predators.

34 Section 1 Check Question 1 What is the major evolutionary step in animals that sponges exhibit? (TX Obj 2; 4B, 8C, 10A, 10B)

35 Section 1 Check Sponges are the first animals to exhibit the change from a unicellular life to a division of labor among groups of organized cells.

36 Section 1 Check Question 2 In sponges, where do fertilized eggs develop into zygotes? (TX Obj 2; 4B, 8C, 10A, 10B) D. in the jelly between the cell layers C. in the collar cells B. in the pore cells A. in the sponge’s osculum

37 Section 1 Check The answer is D, in the jelly between the cell layers.

38 Section 1 Check Question 3 How many layers of cells make up a sponge? (TX Obj 2; 8C) D. five C. four B. three A. two The answer is A, two.

39 26.2 Section Objectives – page 698 Section Objectives Sequence the stages in the life cycle of a cnidarian. Analyze the relationships among the classes of cnidarians. Evaluate the adaptations of cnidarians for obtaining food.

40 Section 26.2 Summary – pages 698-705 Cnidarians (ni DARE ee uns) are a group of invertebrates made up of more than 9000 species of jellyfishes, corals, sea anemones, and hydras. What is a cnidarian? They can be found worldwide, and all but a few cnidarians live in marine biomes.

41 Section 26.2 Summary – pages 698-705 A cnidarian’s body is radially symmetrical. It has one body opening and is made up of two layers of cells. Body structure Cavity Bud Disc Outer cell layer Jellylike layer Inner cell layer Tentacle Mouth

42 Section 26.2 Summary – pages 698-705 Body structure Mouth Cavity Bud Disc Outer cell layer Jellylike layer Inner cell layer Tentacle The two cell layers are organized into tissues with specific functions. The inner layer is adapted mainly to assist in digestion.

43 Section 26.2 Summary – pages 698-705 Because a cnidarian’s body is only two layers of cells, no cell is ever far from water. Oxygen dissolved in water can diffuse directly into body cells. Carbon dioxide and other wastes can move out of a cnidarian’s body cells directly into the surrounding water. Body structure

44 Section 26.2 Summary – pages 698-705 Cnidarians display a remarkable variety of colors, shapes and sizes. Some can be as small as the tip of a pencil. A Cnidarian Most cnidarians have two distinct body forms during their life cycles. A polyp is the sessile form of a cnidarian. Its mouth is surrounded by tentacles. Examples of polyps include sea anemones, corals, and hydras.

45 Section 26.2 Summary – pages 698-705 A medusa is the free- swimming form of a cnidarian. A Cnidarian It possesses an umbrella-shaped, floating body, called a bell, with the mouth on its underside. Tentacles

46 Section 26.2 Summary – pages 698-705 A Cnidarian Tentacles Nematocyst before discharge Nematocyst after discharge Bud Mouth Tentacles Prey

47 Section 26.2 Summary – pages 698-705 Most cnidarians undergo a change in body form during their life cycles. Body form Polyp Medusa

48 Section 26.2 Summary – pages 698-705 Body form There are two body forms, the polyp and the medusa. Polyp Medusa

49 Section 26.2 Summary – pages 698-705 In cnidarians, one body form may be more observable than the other. In jellyfishes, the medusa is the body form usually observed. The polyp is the familiar body form of hydras. Body form

50 Section 26.2 Summary – pages 698-705 All cnidarians have the ability to reproduce sexually and asexually. Reproduction in cnidarians Sexual reproduction occurs in only one phase of the life cycle. It usually occurs in the medusa stage, unless there is no medusa stage then the polyp can reproduce sexually.

51 Section 26.2 Summary – pages 698-705 Reproduction in cnidarians Male Female Eggs Sexual Reproduction Fertilization Blastula Larva Polyp Bud Asexual Reproduction

52 Section 26.2 Summary – pages 698-705 The most common form of reproduction in cnidarians can be illustrated by the life cycle of a jellyfish. Reproduction in cnidarians Even though these two stages alternate in a cnidarian’s life cycle, this form of reproduction is not alternation of generations as in plants. In plants, one generation is diploid and the other is haploid. However, both cnidarian medusae and polyps are diploid animals.

53 Section 26.2 Summary – pages 698-705 Reproduction in cnidarians Asexual reproduction MaleFemale Medusae Sperm Egg Sexual reproduction Larva Polyp

54 Section 26.2 Summary – pages 698-705 Cnidarians are predators that capture or poison their prey using nematocysts. Digestion in cnidarians A nematocyst (nih MA tuh sihst) is a capsule that contains a coiled, threadlike tube. The tube may be sticky or barbed, and it may contain toxic substances. Nematocysts are located in stinging cells that are on tentacles.

55 Section 26.2 Summary – pages 698-705 Once captured by nematocysts, prey is brought to the mouth by contraction of the tentacles. Digestion in cnidarians Polyp Medusa Mouth Gastrovascular cavity Mouth

56 Section 26.2 Summary – pages 698-705 Digestion in cnidarians The inner cell layer of cnidarians surrounds a space called a gastrovascular (gas troh VAS kyuh lur) cavity. Cells adapted for digestion line the gastrovascular cavity and release enzymes over captured prey. Any undigested materials are ejected back out through the mouth. Hydra eating daphnia

57 Section 26.2 Summary – pages 698-705 A cnidarian has a simple nervous system without a control center, such as a brain like that of other animals. Nervous system in cnidarians In cnidarians, the nervous system consists of a nerve net that conducts impulses to and from all parts of the body. The impulses from the nerve net cause contractions of musclelike cells in the two cell layers.

58 Section 26.2 Summary – pages 698-705 There are four classes of cnidarians: Diversity of Cnidarians Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa. Cubozoans once were classified as scyphozoans.

59 Section 26.2 Summary – pages 698-705 The class Hydrozoa includes two groups— the hydroids, such as hydra, and the siphonophores, including the Portuguese man-of-war. Most hydrozoans form colonies Most hydroids are marine animals that consist of branching polyp colonies formed by budding, and are found attached to pilings, shells, and other surfaces.

60 Section 26.2 Summary – pages 698-705 The siphonophores include floating colonies that drift about on the ocean’s surface. Most hydrozoans form colonies The Portuguese man-of-war, Physalia, is an example of a siphonophore hydrozoan colony. Each individual in a Physalia colony has a function that helps the entire organism survive.

61 Section 26.2 Summary – pages 698-705 The fragile and sometimes luminescent bodies of jellyfishes can be beautiful. Scyphozoans are the jellyfishes Some jellyfishes are transparent, but others are pink, blue, or orange. The medusa form is the dominant stage in this class.

62 Section 26.2 Summary – pages 698-705 The gastrovascular cavity of scyphozoans has four internal divisions. Scyphozoans are the jellyfishes Like other cnidarians, scyphozoans have musclelike cells in their outer cell layer that can contract. When these cells contract together, the bell contracts, which propels the animal through the water.

63 Section 26.2 Summary – pages 698-705 Anthozoans are cnidarians that exhibit only the polyp form. Most anthozoans build coral reefs All anthozoans have many incomplete divisions in their gastrovascular cavities. Sea Anemone

64 Section 26.2 Summary – pages 698-705 Most anthozoans build coral reefs Sea anemones are anthozoans that live as individual animals, and are thought to live for centuries. Sea Anemone

65 Section 26.2 Summary – pages 698-705 Corals are anthozoans that live in colonies of polyps in warm ocean waters around the world. Most anthozoans build coral reefs They secrete protective, cuplike calcium carbonate shelters around their soft bodies. Colonies of many coral species build the beautiful coral reefs that provide food and shelter for many other marine species.

66 Section 26.2 Summary – pages 698-705 Corals that form reefs are known as hard corals. Most anthozoans build coral reefs Other corals are known as soft corals because they do not build such structures.

67 Section 26.2 Summary – pages 698-705 The living portion of a coral reef is a thin, fragile layer that grows on top of the shelters left behind by previous generations. Most anthozoans build coral reefs

68 Section 26.2 Summary – pages 698-705 Although corals are often found in relatively shallow, nutrient-poor waters, they thrive because of their symbiotic relationship with microscopic, photosynthetic protists called zooxanthellae (zoh oh zan THEH lee). Most anthozoans build coral reefs

69 Section 26.2 Summary – pages 698-705 The zooxanthellae produce oxygen and food that the corals use, while using carbon dioxide and waste materials produced by the corals. Most anthozoans build coral reefs These protists are primarily responsible for the bright colors found in coral reefs.

70 Section 26.2 Summary – pages 698-705 Because the zooxanthellae are free-swimming, they sometimes leave the corals. Most anthozoans build coral reefs Corals without these protists often die.

71 Section 26.2 Summary – pages 698-705 The earliest fossil evidence for sponges dates this group to late in the Precambrian, about 650 million years ago. Origins of Sponges and Cnidarians The earliest known cnidarians also date to the Precambrian, about 630 million years ago.

72 Section 26.2 Summary – pages 698-705 Origins of Sponges and Cnidarians

73 Section 26.2 Summary – pages 698-705 The earliest coral species were not reef builders, so reefs cannot be used to date early cnidarians. Origins of Sponges and Cnidarians The larval form of cnidarians resembles protists, and because of this, scientists consider cnidarians to have evolved from protists.

74 Section 2 Check Which of the following features is NOT common to both sponges and cnidarians? (TX Obj 2; 4B, 8C, 10A, 10B) Question 1 D. reproduce both sexually and asexually C. sessile B. radial symmetry A. body made up of two layers of cells The answer is B.

75 Section 2 Check Explain the difference between the ways cnidarians and sponges take in food. (TX Obj 2; 4B, 8C, 10A, 10B) Question 2 Answer Sponges passively filter food particles from the water when the particles flow through the sponge. Cnidarians actively seek food with tentacles that capture or paralyze the prey and take it to the cnidarian’s mouth for ingestion.

76 Section 2 Check Explain how each of the two forms in the figure below benefits from contractions of muscle-like cells caused by impulses from its nerve net. (TX Obj 2; 4B, 8C, 10A,10B) Question 3 Polyp Medusa Mouth Gastrovascular cavity Mouth

77 Section 2 Check In the sessile polyp form, cell contractions cause tentacles to move prey toward the mouth. In the free-swimming form, cell contractions help the medusa to swim and find food. Polyp Medusa Mouth Gastrovascular cavity Mouth

78 Section 2 Check Which of the following is NOT true of cnidarian budding? (TX Obj 2; 4B, 8C, 10A, 10B) Question 4 D. it is part of asexual reproduction C. it produces haploid organisms B. it produces clones of the parents A. it can form colonies of individuals

79 Section 2 Check The answer is C. Budding produces diploid organisms.

80 26.3 Section Objectives – page 706 Distinguish between the structural adaptations of parasitic flatworms and free-living planarians. Section Objectives: Explain how parasitic flatworms are adapted to their way of life.

81 Section 26.3 Summary– pages 706-710 The least complex worms belong to the phylum Platyhelminthes (pla tee HEL min theez). What is a flatworm? These flatworms are acoelomates with thin, solid bodies. Planarian

82 Section 26.3 Summary– pages 706-710 What is a flatworm? There are approximately 14,500 species of flatworms found in marine and freshwater environments and in moist habitats on land. Planarian

83 Section 26.3 Summary– pages 706-710 The most well-known members of this phylum are the parasitic tapeworms and flukes, which cause diseases in other animals, among them frogs and humans. What is a flatworm? The most commonly studied flatworms in biology classes are the free-living planarians.

84 Section 26.3 Summary– pages 706-710 Most of a planarian’s nervous system is located in its head—a characteristic common to other bilaterally symmetrical animals. Nervous control in planarians Nerve cell mass

85 Section 26.3 Summary– pages 706-710 Nervous control in planarians Some flatworms have a nerve net, and others have the beginnings of a central nervous system.

86 Section 26.3 Summary– pages 706-710 A planarian’s nervous system includes two nerve cords that run the length of the body. Nervous control in planarians Ganglia Eyespots Nerve cord Muscle cells

87 Section 26.3 Summary– pages 706-710 Nervous control in planarians It also includes eyespots that can detect the presence or absence of light and sensory cells that can detect chemicals and movement in water. Ganglia Eyespots Nerve cord Muscle cells

88 Section 26.3 Summary– pages 706-710 At the anterior end of the nerve cord is a small swelling called a ganglion (plural, ganglia). The ganglion receives messages from the eyespots and sensory pits, then communicates with the rest of the body along the nerve cords. Nervous control in planarians Ganglia Messages from the nerve cords trigger responses in a planarian’s muscle cells.

89 Section 26.3 Summary– pages 706-710 Like many of the organisms studied in this chapter, most flatworms including planarians, are hermaphrodites. Reproduction in planarians During sexual reproduction, individual planarians exchange sperm, which travel along special tubes to reach the eggs.

90 Section 26.3 Summary– pages 706-710 Fertilization occurs internally. The zygotes are released in capsules into the water, where they hatch into tiny planarians. Reproduction in planarians

91 Section 26.3 Summary– pages 706-710 Planarians have many characteristics common to all species of flatworms. A Planarian The bodies of planarians are flat, with both a dorsal and a ventral surface. All flatworms have bilateral symmetry.

92 Section 26.3 Summary– pages 706-710 A Planarian Head Eyespots Sensory cells Extended pharynx Flame cell Cilia Mouth Digestive tract Nucleus Cilia Excretory system

93 Section 26.3 Summary– pages 706-710 Planarians also can reproduce asexually. Reproduction in planarians When a planarian is damaged, it has the ability to regenerate, or regrow, new body parts. Regeneration is the replacement or regrowth of missing body parts.

94 Section 26.3 Summary– pages 706-710 If a planarian is cut horizontally, the section containing the head will grow a new tail, and the tail section will grow a new head. Reproduction in planarians

95 Section 26.3 Summary– pages 706-710 Reproduction in planarians Thus, a planarian that is damaged or cut into two pieces may grow into two new organisms—a form of asexual reproduction.

96 Section 26.3 Summary– pages 706-710 A planarian feeds on dead or slow-moving organisms. Feeding and digestion in planarians It extends a tube-like, muscular organ, called the pharynx (FAHR inx), out of its mouth. Enzymes released by the pharynx begin digesting food outside the animal’s body. Extended pharynx

97 Section 26.3 Summary– pages 706-710 Food particles are sucked into the digestive tract, where they are broken up. Feeding and digestion in planarians Cells lining the digestive tract obtain food by endocytosis. Food is thus digested in individual cells.

98 Section 26.3 Summary– pages 706-710 A parasite is an organism that lives on or in another organism and depends upon that host organism for its food. Feeding and digestion in parasitic flatworms Parasitic flatworms have mouthparts with hooks that keep the flatworm firmly attached inside its host. Hooks Scolex Sucker Proglottid Mature proglottid with fertilized eggs

99 Section 26.3 Summary– pages 706-710 They do not need to move to seek out or find food. Feeding and digestion in parasitic flatworms Parasitic flatworms do not have complex nervous or muscular tissue.

100 Section 26.3 Summary– pages 706-710 The body of a tapeworm is made up of a knob-shaped head called a scolex (SKOH leks), and detachable, individual sections called proglottids. Tapeworm bodies have sections Hooks Scolex Sucker Proglottid Mature proglottid with fertilized eggs

101 Section 26.3 Summary– pages 706-710 Tapeworm bodies have sections A proglottid (proh GLAH tihd) contains muscles, nerves, flame cells, and male and female reproductive organs. Hooks Scolex Sucker Proglottid Mature proglottid with fertilized eggs

102 Section 26.3 Summary– pages 706-710 Some adult tapeworms that live in animal intestines can be more than 10 m in length and consist of 2000 proglottids. Tapeworm bodies have sections

103 Section 26.3 Summary– pages 706-710 A fluke is a parasitic flatworm that spends part of its life in the internal organs of a vertebrate, such as a human or sheep. The life cycle of a fluke It obtains its nutrition by feeding on cells, blood, and other fluids of the host organism.

104 Section 26.3 Summary– pages 706-710 The life cycle of a fluke Adult flukes Embryos released Larva Snail host Larva Human host

105 Section 26.3 Summary– pages 706-710 Blood flukes of the genus Schistosoma cause a disease in humans known as schistosomiasis. The life cycle of a fluke Schistosomiasis is common in countries where rice is grown. Blood flukes are common where the secondary host, snails, also are found.

106 Section 3 Check In order to survive and reproduce, a parasite must have a _______. (TX Obj 2; 4B, 8C, 10A, 10B) Question 1 D. host C. scolex B. proglottid A. pharynx

107 The answer is D, host. Section 3 Check

108 Explain the way planarians can reproduce asexually. (TX Obj 2; 4B, 8C, 10A, 10B) Question 2

109 When a planarian is damaged, it can regenerate new body parts. It can also regenerate new organisms if cut into separate pieces. Section 3 Check

110 26.4 Section Objectives – page 711 Compare and contrast the structural adaptations of roundworms and flatworms. Section Objectives: Identify the characteristics of four roundworm parasites.

111 Section 26.4 Summary– pages 711-713 Roundworms belong to the phylum Nematoda. What is a roundworm? They are widely distributed, living in soil, animals, and both freshwater and marine environments. Most roundworm species are free- living, but many are parasitic. Roundworm

112 Section 26.4 Summary– pages 711-713 Roundworms are tapered at both ends. What is a roundworm? They have a thick outer covering, which they shed four times as they grow, that protects them in harsh environments. Mouth Intestine Anus Round body shape

113 Section 26.4 Summary– pages 711-713 They lack circular muscles but have lengthwise muscles. What is a roundworm? As one muscle contracts, another muscle relaxes. This alternating contraction and relaxation of muscles causes roundworms to move in a thrashing fashion.

114 Section 26.4 Summary– pages 711-713 Roundworms have a pseudocoelom and are the simplest animals with a tubelike digestive system. What is a roundworm? Roundworms have two body openings— a mouth and an anus. Mouth Intestine Anus Round body shape

115 Section 26.4 Summary– pages 711-713 What is a roundworm? The free-living species have well-developed sense organs, such as eyespots, although these are reduced in parasitic forms. Mouth Intestine Anus Round body shape

116 Section 26.4 Summary– pages 711-713 Approximately half of the described roundworm species are parasites, and about 50 species infect humans. Diversity of Roundworms

117 Section 26.4 Summary– pages 711-713 Infection by Ascaris (ASS kuh ris) is the most common roundworm infection in humans. Roundworm parasites of humans Children become infected more often than adults do. Eggs of Ascaris are found in soil and enter a human’s body through the mouth.

118 Section 26.4 Summary– pages 711-713 The eggs hatch in the intestines, move into the bloodstream, and eventually to the lungs, where they are coughed up, swallowed, and begin the cycle again. Roundworm parasites of humans

119 Section 26.4 Summary– pages 711-713 Pinworms are the most common human roundworm parasites in the United States. Roundworm parasites of humans Pinworms are highly contagious because eggs can survive for up to two weeks on surfaces.

120 Section 26.4 Summary– pages 711-713 Its life cycle begins when live eggs are ingested. They mature in the host’s intestinal tract. Roundworm parasites of humans Female pinworms exit the host’s anus— usually as the host cell sleeps—and lay eggs on nearby skin. These eggs fall onto bedding or other surfaces.

121 Section 26.4 Summary– pages 711-713 Trichinella causes a disease called trichinosis (tri keh NOH sis). Roundworm parasites of humans This roundworm can be ingested in raw or undercooked pork, pork products, or wild game. Trichinella

122 Section 26.4 Summary– pages 711-713 Hookworm infections are common in humans in warm climates where they walk on contaminated soil in bare feet. Roundworm parasites of humans Hookworms cause people to feel weak and tired due to blood loss.

123 Section 26.4 Summary– pages 711-713 Nematodes can infect and kill pine trees, cereal crops, and food plants such as potatoes. Roundworm parasites of other organisms They are particularly attracted to plant roots and cause a slow decline of the plant.

124 Section 26.4 Summary– pages 711-713 They also can infect fungi and can form symbiotic associations with bacteria. Roundworm parasites of other organisms Nematodes also can be used to control pests.

125 Section 4 Check Which of the following is NOT a feature of roundworms? (TX Obj 2; 4B, 8C, 10A, 10B) Question 1 D. scolex C. outer covering that can be shed B. anus A. pseudocoelom

126 The answer is D, scolex. Section 4 Check

127 Which of the following parasites embeds itself inside the host’s muscle tissue? (TX Obj 2; 4B, 8C, 10A, 10B) Question 2 D. Pinworms C. Ascaris B. Trichinella A. Tapeworms

128 The answer is B. Trichinella is found in pork muscle tissue and can invade the muscle tissue of humans who eat undercooked infected pork. Section 4 Check

129 Chapter Summary – 26.1 A sponge is an aquatic, sessile, asymmetrical, filter-feeding invertebrate. Sponges Sponges are made of four types of cells. Each cell type contributes to the survival of the organism. Most sponges are hermaphroditic with free-swimming larvae.

130 Chapter Summary – 26.2 All cnidarians are radially symmetrical, aquatic invertebrates that display two basic forms: medusa and polyp. Cnidarians Cnidarians sting their prey with cells called nematocysts located on their tentacles. The three primary classes of cnidarians include the hydrozoans, hydras; schyphozoans, jellyfishes; and anthozoans, corals and anemones.

131 Chapter Summary – 26.3 Flatworms are acoelomates with thin, solid bodies. They are grouped into three classes: free-living planarians, parasitic flukes, and tapeworms. Flatworms Planarians have simple nervous and muscular systems. Flukes and tapeworms have structures adapted to their parasitic existence.

132 Chapter Summary – 26.4 Roundworms are pseudocoelomate, cylindrical worms with lengthwise muscles, relatively complex digestive systems, and two body openings. Roundworms Roundworms can be parasites of plants, fungi, and animals, including humans.

133 Chapter Assessment Question 1 Which of the following is NOT a method of asexual reproduction in sponges? (TX Obj 2; 4B, 8C, 10A, 10B) D. flagellated larvae C. gemmule formation B. fragmentation A. budding

134 The answer is D. Flagellated larvae result from sexual reproduction. Chapter Assessment

135 Question 2 In hermaphroditic sponges, eggs and sperm form from _______. (TX Obj 2; 4B, 8C, 10A, 10B) D. collar cells C. amoebocytes B. epithelial cells A. larvae

136 The answer is C, amoebocytes. Amoebocyte Chapter Assessment

137 Question 3 Describe the symbiotic relationship between corals and zooxanthellae. (TX Obj 2; 4B, 8C, 10A, 10B)

138 Zooxanthellae produce oxygen and food that the corals use. The corals produce carbon dioxide and waste materials that the zooxanthellae use. Chapter Assessment

139 Question 4 The cnidarians with many incomplete divisions in their gastrovascular cavities are the _______. (TX Obj 2; 4B, 8C, 10A, 10B) D. Siphonophores C. Anthozoans B. Hydrozoans A. Scyphozoans

140 The answer is C, Anthozoans. Chapter Assessment

141 Question 5 The medusa is the body form usually observed in _______. (TX Obj 2; 4B, 8C, 10A, 10B) D. Anthozoans C. Siphonophores B. Hydrozoans A. Scyphozoans

142 The answer is A, Scyphozoans. Chapter Assessment

143 Question 6 How is a secondary host involved in the life cycle of a tapeworm? (TX Obj 2; 4B, 8C, 10A, 10B) Answer The eggs of the tapeworm hatch when a secondary host eats them.

144 Chapter Assessment Question 7 The secondary host for the blood fluke is a _______. TX Obj 2; 4B, 8C, 10A, 10B) D. dog C. snail B. sheep A. human

145 The answer is C, snail. Chapter Assessment

146 Question 8 The simplest animals with a tube-like digestive system are _______. (TX Obj 2; 4B, 8C, 10A, 10B) D. Anthozoans C. Hydrozoans B. Platyhelminthes A. Nematodes

147 The answer is A, Nematodes. Roundworm Chapter Assessment

148 Question 9 Which of the following is not a roundworm infection in humans? (TX Obj 2; 4B, 8C, 10A, 10B) D. ascaris C. pinworm B. ringworm A. hookworm

149 The answer is B. Ringworm is a fungal infection. Chapter Assessment

150 Photo Credits Digital Stock Ward's Natural Science Est. Kip Evans/NOAA Florida Keys National Marine Sanctuary/NOAA Carolina Biological Supply Co. Dr. John Crites David M. Dennis Alton Biggs Photo Credits

151 To advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow. Click on this icon to return to the table of contents Click on this icon to return to the previous slide Click on this icon to move to the next slide Click on this icon to open the resources file.

152 End of Chapter 26 Show


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