Chapter 26: Sponges, Cnidarians, Flatworms, and Roundworms

Sponges, Cnidarians, Chapter 26 Organizer Flatworms, and Roundworms

Refer to pages 4T-5T of the Teacher Guide for an explanation of the National Science Education Standards correlations. Teacher Classroom Resources Activities/FeaturesObjectivesSection MastersSection TransparenciesReproducible

Reinforcement and Study Guide, p. 115 L2 Section Focus Transparency 63 L1 ELL Section 26.1 1. Relate the sessile life of sponges to their Inside Story: A Sponge, p. 714 Section 26.1 food-gathering adaptations. Problem-Solving Lab 26-1: p. 715 Concept Mapping, p. 26 L3 ELL Basic Concepts Transparency 45 L2 ELL Sponges 2. Describe the reproductive adaptations Sponges Critical Thinking/Problem Solving, p. 26 L3 Basic Concepts Transparency 46 L2 ELL NSES UCP.1, UCP.5; C.1, of sponges. Content Mastery, pp. 129-132 L1 P 1 C.5-6 ( /2 session) P P Reinforcement and Study Guide, p. 116 L2 Section Focus Transparency 64 L1 ELLP Section 26.2 P BioLab and MiniLab Worksheets, p. 117 L2P Basic Concepts Transparency 45 L2 ELL Section 26.2 3. Distinguish the different classes of MiniLab 26-1: Watching Hydra Feed, p. 719 P LS Cnidarians Laboratory Manual, pp. 187-188 L2 Basic Concepts Transparency 46 L2P ELL cnidarians. Inside Story: A Cnidarian, p. 720 LS P LS Cnidarians 4. Sequence the stages in the life cycle of Problem-Solving Lab 26-2: p. 724 Basic Concepts Transparency 47 L2P PLSELL NSES UCP.1, UCP.3, UCP.5; cnidarians. Biology & Society: Why are the corals LS LS P A.1, A.2; C.1, C.3, C.5-6; F.3, 5. Evaluate the adaptations of cnidarians dying? p. 736 Reinforcement and Study Guide, p. 117 L2LS Section Focus Transparency 65 L1 ELLP F.4 (1 session) for obtaining food. Section 26.3 P LS Laboratory Manual, pp. 189-190 L2 P Reteaching Skills Transparency LS39LSL1LSP ELL Flatworms Content Mastery, pp. 129-132 L1 P P P LS Section 26.3 6. Distinguish the adaptive structures Problem-Solving Lab 26-3: p. 727 P P PLS of parasitic flatworms and free-living Inside Story: A Planarian, p. 728 Reinforcement and Study Guide,LSp. 118 L2 Section Focus Transparency 66 L1P ELLP Section 26.4 LS LS Flatworms planarians. Investigate BioLab: Observing Planarian BioLab and MiniLab Worksheets, pp. 118-120LS L2 LS NSES UCP.1, UCP.5; A.1; 7. Explain how parasitic flatworms are Regeneration, p.734 Roundworms Content Mastery, pp. 129-132 L1 P LS adapted to their way of life. LS LS LS C.3, C.5-6; F.1, F.5; G.1 P P (1 session) Assessment Resources Additional Resources PLS LS P Chapter Assessment, pp. 151-156 P SpanishLS Resources L1 ELL P Section 26.4 8. Compare the structural adaptations MiniLab 26-2: Observing the Larval Stage of MindJogger Videoquizzes LS English/Spanish Audiocassettes L1 ELL LS of roundworms and flatworms. a Pork Worm, p. 732 Performance Assessment in the Biology Classroom CooperativeP Learning in the Science Classroom LS Roundworms 9. Identify the characteristics of four Problem-Solving Lab 26-4: p. 733 COOPP LEARN Alternate Assessment in the Science Classroom Lesson Plans/Block SchedulingP LS NSES UCP.1, UCP.5; A.1, roundworm parasites. LS A.2; C.5-6; E.1, E.2; F.1, F.5; Computer Test Bank P LS P G.1, G.2 (11/ sessions) BDOL Interactive CD-ROM, Chapter 26 quiz LS 2 LS LS LS LS P LS Need Materials? Contact Carolina Biological Supply Company at 1-800-334-5551 KeyKey toto TeachingTeaching StrategiesStrategies or at http://www.carolina.com P L1 Level 1 activities should be appropriate Teacher’s MATERIALS LIST for students with learning difficulties. Corner L2 Level 2 activities should be within the LS BioLab Alternative Lab ability range of all students. The following multimedia resourcesLS are available from Glencoe. Index to National Geographic Magazine p. 734 planarian culture, petri dish, p. 714 stereomicroscope, forceps, L3 Level 3 activities are designed for above- Biology: The Dynamics of Life The following articles may be used for springwater, camel hair brush, micro- balance, wax pencil, beakers, petri dish, average students. CD-ROM ELL research relating to this chapter: scope slide, stereomicroscope, single- sea sponges, unused synthetic sponges ELL ELL activities should be within the ability Video: Ocean Cnidarians “Consider the Sponge,” by Michael E. Long, edged razor blade, marking pencil range of English Language Learners. Video: Coral Reefs Quick Demos March 1977. P COOP LEARN Cooperative Learning activities BioQuest: Biodiversity Park MiniLabs p. 716 dried marine sponges P P are designed for small group work. p. 719 microscope, watch glass, drop- p. 720 microprojector, prepared slides P Videodisc Program P These strategies represent student prod- per, culture dish, hydra culture, brine of nematocysts P Ocean Cnidarians ucts that can be placed into a best-work shrimp culture, water p. 728 slide projector, planarian P portfolio. LS p. 732 microscope, prepared slide of culture, water, 35-mm deep-well slide The InfiniteLS Voyage LS These strategies are useful in a block pork worm larvae LS To the Edge of the Earth LS scheduling format. LS

712A 712B ChapterChapter 2626 ChapterChapter SECTION PREVIEW Section Objectives Section 26.1 Relate the sessile life of Sponges, Cnidarians, sponges to their food- 26.1 Sponges gathering adaptations. ETTING TARTED EMO GETTING STARTED DEMO 26 Describe the reproduc- Prepare Flatworms, and tive adaptations of Visual-Spatial Have stu- sponges. Key Concepts dents observe the live Vocabulary freshwater sponge, Spongilla, Roundworms s this red organism a plant or an filter feeding Students will learn the main fea- animal? At first glance, it may look hermaphrodite with hand lenses. Ask students tures of sponges and discuss their like a plant because it is colorful and external fertilization I internal fertilization adaptations, origins, and ecology. to note the asymmetrical shape What You’ll Learn doesn’t move from place to place, but it is of the sponge and its many You will compare and con- an animal. How do you know this organ- pores. Explain that all sponges Planning P trast the characteristics of ism is an animal? Like snakes, spiders, have a large number of pores. sponges, cnidarians, flat- and you, this organism is eukaryotic, Collect dried natural and syn- L2 ELL worms, and roundworms. thetic sponges for the Altern- You will describe how multicellular, and heterotrophic— characteristics that place it in the ative Lab and Quick Demo. sponges, cnidarians, flat- LS worms, and roundworms are animal kingdom. This sessile Gather butcher paper and col- Theme PDevelopment adapted to their habitats. animal is a sponge that filters ored markers for the Check water through many small for Understanding. The themes of evolution and Why It’s Important Red sponge, pores on the outside of its body. Haliclona sp. homeostasis are emphasized in Sponges and cnidarians are two thisP chapter. Evolutionary rela- major groups of animals that tionshipsLS among the animal phyla are important to aquatic bio- mes. Flatworms and round- 1 Focus are stressed, as are adaptations to worms include many species the environment and the homeo- that cause diseases that affect Bellringer static mechanisms at work in the both plants and animals. LS What Is a Sponge? No matter where sponges live, WORD Origin Before presenting the lesson, dis- different animals. they are mainly sessile organisms. porifera play Section Focus Trans- Sponges are asymmetrical aquatic Because most adult sponges are GETTING STARTED From the Latin parency 63 on the overhead animals that have a variety of colors, sessile, they can’t travel in search of words porus, mean- projector and have students Observing a Sponge shapes, and sizes. Many are bright food. Sponges get their food by ing “pore,” and fera, answer the accompanying ques- Look at a natural bath sponge shades of red, orange, yellow, and filter feeding, a method in which meaning “bearer.” If time does not permit teach- using a hand lens or under a green. Some sponges are ball shaped; Phylum Porifera tions. L1 ELL binocular microscope. Does a an organism feeds by filtering small ing the entire chapter, use the others have many branches. Sponges particles of food from water as it includes animals sponge have a skeleton? with pores that BioDigest at the end of the can be as small as a quarter or as passes by or through some part of the unit as an overview. large as a door. Although sponges do allow water to flow To find out SECTION FOCUS organism. How does a sponge get rid through their Transparency 63 PSponges Use with Chapter 26, not resemble more familiar animals, Section 26.1 more about of its wastes? Find out by reading the bodies. sponges, cnidarians, flatworms, they carry on the same life processes Inside Story. and roundworms, visit the as all animals. Figure 26.1 shows a Glencoe Science Web Site. natural sponge harvested from the www.glencoe.com/sec/science ocean. LS P Sponges are pore-bearers Figure 26.1 CD-ROM Sponges are classified in the inver- This heavy bath sponge Biology: The Dynamics tebrate phylum Porifera, which means is dark brown or black in Sponge its natural habitat. After of Life Exploration: pore-bearer. Of the 5000 described The Five Kingdoms Disc 3 The sea anemone and the harvest, it is washed and dried LS sponge (inset) share common species of sponges, most live in the in the sun. When the process traits. Both are invertebrates ocean; only 100 species can be found is complete, only a pale, light- with simple body plans. in freshwater environments. weight skeleton remains. 1 What does the body shape of this sponge suggest about the way it gets food? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2 What are the advantages and disadvantages of being ResourceResource 712 713 permanently attached to a surface, as this sponge is? ManagerManager BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES AssessmentAssessment PlannerPlanner Section Focus Transparency 63 Look for the following logos for strategies that emphasize different learning modalities. and Master L1 ELL Portfolio Assessment Knowledge Assessment Multiple Kinesthetic Quick Demo p. 716; Intrapersonal Cultural Diversity, Problem-Solving Labs, TWE, pp. 715, 732 Section Assessments, SE, pp. 717, 725, Learning Building a Model, p. 722 p. 718; Going Further, p. 736 Portfolio, TWE, pp. 722, 727, 733 730, 733 Visual-Spatial Biology Journal, Linguistic Enrichment, p. 716; BioLab, TWE, p. 735 Problem-Solving Lab, TWE, p. 727 P Styles p. 716; Meeting Individual Portfolio, p. 727 Performance Assessment Chapter Assessment, SE, pp. 737-739 Needs, pp. 716, 723; Visual Learning, Naturalist Meeting Individual Performance Assessments, TWE, pp. 716, Knowledge Assessment, TWE, pp. 729, p. 720, Biology Journal, pp. 721, 723, Needs, p. 728; Check for Under- 717, 723, 725 730 729; Display, p. 721; Tech Prep, p. 729 standing, p. 729; Portfolio, p. 731 Problem-Solving Lab, TWE, p. 724 Skill Assessment LS Interpersonal Portfolio, p. 722; BioLab, SE, p. 734-735 Alternative Lab, TWE, p. 715 712 P Reteach, p. 725 MiniLabs, SE, p. 719, 732 Problem-Solving Lab, TWE, p. 732 713

LS 2 Teach NSIDE Cell organization in sponges Problem-Solving Lab 26-1 IINSIDE Like all animals, sponges are multi- Problem-Solving Lab 26-1 Applying Concepts P cellular. Sponges have different types STORY Purpose of cells that perform functions that Why are there more species of marine sponges than NSIDENSIDE help the animal survive. Read the freshwater sponges? Most sponges are marine. They live in Students will determine that II A Sponge Problem-Solving Lab on this page to a saltwater environment. Is there an advantage for sponges freshwaterLS environments are to live in a marine environment rather than in a freshwater more difficult for sponge survival SP TORY find out how sponges survive in dif- ponges have no tissues, organs, or organ systems. The ferent environments. The activities environment? A series of statements is provided below. Read than saltwater environments. them over and then answer the questions that follow. Purpose Sbody plan of a sponge is simple, being made up of only of the different types of cells are Process Skills Students will observe the basic two layers of cells with no body cavity. Between these two coordinated in a sponge, but sponges Analysis features of a sponge and examine layers is a jellylike substance that contains other cells as do not have tissues like those found A. The internal tissues of marine organisms are isotonic with think critically, analyze data, LS their surroundings. how it accomplishes filter feeding. well as the components of the sponge’s internal support in other animals. Tissues are groups compare and contrast, draw a system. Sponges have four types of cells that perform all of cells that are derived from the B. Oceans do not have problems with rapid changes in velocity (rate of flow) of water. conclusion Teaching Strategies the functions necessary to keep them alive. Orange tube sponges ectoderm, endoderm, and mesoderm C. Young marine animals often spend the early part of their in the embryo. Sponge embryos do Teaching Strategies Explain that sponges obtain life cycles as free-floating organisms. Critical Thinking Why are sponges classified as animals? not develop endoderm or mesoderm, food in a process called filter You may want to review osmo- so they do not have cells organized Thinking Critically feeding. 1. Using statement A, how might a freshwater environment sis with students. into tissues. Review the concepts of fresh- 1 Osculum Water and wastes However, the cells of a sponge are vary? How might this be a disadvantage for freshwater Visual Learning are expelled through the sponges? water versus saltwater environ- 4 Collar cell Lining the organized. If you took a living osculum, the large opening 4 2. Using statement B, how might a freshwater environment Point out that food particles in interior of sponges are ments. Make sure students at the top of the sponge. sponge and put it through a sieve, vary? How might this be a disadvantage for freshwater water are pulled into collar cells collar cells. Each collar cell understand that lakes, streams, A sponge no bigger than you would witness a rather remark- sponges? has a flagellum that whips and rivers are freshwater environ- and digested. Nutrients from a pen can move more able event. Not only would you see 3. Using your collective answers, explain why few sponge food are then distributed by than 20 L of water through back and forth, drawing ments. water through the pores the sponge’s many cells alive and sep- species are found in freshwater environments. amoebocytes to other body cells. its body per day. arated out, but you also would be Pore cell of the sponge. Thinking Critically able to see these same cells coming Critical Thinking 1. 5 Amoebocytes together to form a whole sponge The internal environment of 2 Pore cell Surrounding 5 Sponges carry on the same life Amoebocytes, located once again. It may take several weeks attached to the parents, forming a freshwater sponges is not iso- each pore is a single pore for the sponge’s cells to reorganize colony of sponges. You can see a processes as all animals. They are cell. Pore cells bring between the two cell tonic with its surroundings, multicellular eukaryotes that do not water carrying food and layers of a sponge, carry themselves. colony in Figure 26.2. thus energy must be used to have cell walls around their cells. oxygen into the sponge’s nutrients to other cells, Many biologists hypothesize that eliminate excess water from body. aid in reproduction, and sponges evolved directly from colo- produce chemicals that cells of the organism. nial, flagellated protists, such as Figure 26.2 Direction of help make up the Sponge colonies are the 2. The flow of water may be water flow Volvox. More importantly, however, ResourceResource spicules of sponges. result of asexual repro- rapid in rivers or streams, Manager 3 Epithelial cell sponges demonstrate what appears to duction. How would Manager Epithelial cells are thin have been a major step in the evolu- these sponges thus washing adult or embry- and flat. They contract 6 Spicules Spicules are compare geneti- onic sponges away. Basic Concepts Transparen- 6 tion of animals—the change from a in response to touch or structures produced by other unicellular life to a division of labor cally? Could they 3. Many environmental factors cies 45 and 46 and to irritating chemicals, cells that form the hard support among groups of organized cells. be considered in freshwater environments Masters L2 ELL and in so doing, close systems of sponges. Spicules are clones? limit or make it impossible Concept Mapping, p. 26 L3 up pores in the small, needlelike structures Reproduction in sponges for sponges to survive. Critical Thinking/Problem sponge. located between the cell layers of a sponge. Sponges reproduce both sexually Solving, p. 26 PL3 and asexually. They reproduce asexu- ally when fragments break off from Assessment the parent animal and form new Portfolio Ask students to P sponges, or by forming external buds. P Buds may break off, float away, and research the number of sponge LS species that live in freshwater P eventually settle and become separate animals. Sometimes the buds remain environments. L2 P LS LS 714 715 LS LS Alternative Lab Materials 1. Examine each piece of sponge at its minutes and again obtain the mass of natural sponges Assessment stereomicroscope, forceps, balance, wax thinnest point under the microscope. each sponge. 2. Of what adaptive value is it for a Skill Design and conduct an marking pencil, 150 mL beakers, Petri dish 2. Draw the skeletal framework of each 5. Calculate the mass of the water sponge to be able to take in large P Natural and Synthetic Sponges experiment to determine whether the P bottoms, sea sponges (one piece each of sponge. Label each sponge piece. absorbed by each sponge. Compare amounts of water? They are filter feed- temperature of water affects the water- four different types: grass, yellow, sheep’s 3. Predict which type of sponge will hold the data for all sponges. ers. Taking in more water increases the Purpose holding capacity of a sponge. Use wool, hard head—each piece 3 cm 3 cm more water. Base your prediction on chances of taking in more food. Students will compare the water-holding Expected Results the Performance Task Assessment List 2 cm), unused synthetic sponges (one microscopic examination of the sponge P capacity and microscopic appearance of nat- Natural sponges have greater water hold- for Designing an ExperimentLS in PASC, piece each of four different types—each structures. ural and syntheticLS sponges. Remind students ing capacity than synthetic sponges. p. 23. L3 ELL piece 3 cm 3 cm 2 cm) 4. Place each sponge piece in a Petri dish to wash their hands after handling sponges. Analysis Procedure and obtain its mass. Soak each sponge 1. Which sponges, natural or synthetic, 714 Give students the following directions. piece in a beaker of water for 10 have greater water-holding capacity? LS 715 P

P

LS LS Enrichment Reteach Most sponges reproduce sexually. fertilization occurs outside the a Linguistic Some sponges Some sponges have separate sexes, animal’s body. Most sponges have Have students construct an out- give off toxic chemicals that but most sponges are hermaphro- internal fertilization, in which eggs Figure 26.4 line to summarize this section. The spicules of fresh- deter predators and the buildup dites. A hermaphrodite (hur MAF remain inside the animal’s body, and Have them include the phylum, water sponges, such of other sessile animals on their ruh dite) is an individual animal that sperm are carried to the eggs in the as this lake sponge, symmetry, habitat, food-getting exterior surfaces. One of these can produce both eggs and sperm. flow of water. In sponges, the collar protect it from preda- process, reproductive process, chemicals, from a Caribbean Hermaphrodism increases the likeli- cells collect the sperm and transfer tors (a). Spicules of and means of protection of sponge, is being used currently to hood of fertilization in sessile or them to amoebocytes. The amoebo- the deep-water glass sponges. L1 slow-moving animals. Eggs and cytes then transport the sperm to sponges form a rigid treat cancer. Other chemicals skeleton (b). produced by sponges are being sperm are formed from amoebo- ripe eggs. Most sponges reproduce Extension used to fight fungal infections. cytes. During reproduction, sperm sexually through internal fertiliza- released from one sponge can be car- tion. The result is the development Kinesthetic Ask student Have interested students research b groups to construct a three- this subject and write a report. ried by water currents to another of free-swimming, flagellated larvae, sponge, where fertilization may shown in Figure 26.3. dimensional, cutaway model of a L3 sponge. Have students label the occur. Some freshwater sponges that live P Fertilization in sponges may be in temperate waters produce seedlike parts of their model. L2 ELL either external or internal. A few particles, called gemmules, in the fall. COOP LEARN Assessment Figure 26.3 P Sponges reproduce sponges have external fertilization, The adult sponges die over the win- Support and defense systems have an inter- Performance Have stu- sexually when sperm in which the eggs and sperm ter, but the gemmules survive and P in sponges nal skeleton LS P dentsP assume that a particular from one sponge are both released into the water; grow into new sponges in the spring. Sponges are soft-bodied inverte- made of silica Assessment marine sponge harbors single- fertilize the eggs of another sponge. brates, yet they can be found in or of spongin, a PerformanceLS Have stu- celled algae as symbionts in its waters as deep as 8500 m. You might fibrous proteinlike dents make a flowchart that shows cells. Ask students to make a LS B Eggs fertilized think that the water pressure at such material. Sponges can be the events involved inP sexualLS sketchLS and describe in a para- internally develop depths would flatten sponges, yet classified according to their spicules reproduction of sponges. L2 graph what the best shape would A Sperm are into zygotes in the they all have an internal support sys- and/or skeletons. be for this sponge to enable the released into jellylike substance tem that enables them to withstand Besides sharp spicules, some P the water and between cell lay- such pressure. Some sponges have sponges may have other methods algae to get maximum sunlight. travel to other ers, eventually LS L2 ELL P sponges. becoming free- sharp, hard spicules located between of defense. Some tropical sponges 4 Close swimming larvae. the cell layers. Spicules may be made contain chemicals that are toxic to of glasslike material or of calcium fishes and to other predators. Many Discussion LS carbonate. Some species, such as the sponges produce toxins that are Quick Demo Discuss with students situationsP P river sponge shown in Figure 26.4, poisonous to sharks. Scientists are LS in which natural sponges are have thousands of tiny, sharp, needle- studying sponge toxins to identify Kinesthetic From a sci- more desirable than synthetic entific supply house, like spicules that make them hard those that possibly could be used as for animals to eat. Other sponges medicines. sponges, such as for bathing. PobtainLS the dried skeletons of a Explain that natural spongesLS are variety of marine sponges. Ask not used for many cleaning pur- students to examine them and poses because of their expense. describe how these animals Section Assessment P LSwould be different if they Understanding Main Ideas Thinking Critically were alive. L2 ELL 1. How does a sponge obtain food? 5. What advantages for obtaining food do ResourceResource 2. Explain how epithelial cells control filter feeding multicellular organisms such as sponges have in sponges. over unicellular organisms? Explain. ManagerManager LS D After several days, a larva 3. Describe the steps involved in the sexual P attaches itself to a surface and reproduction of sponges. SKILL REVIEWEVIEW Reinforcement and Study develops into an adult. Most C The larvae swim 4. What are the functions of amoebocytes in 6. Making and Using Tables Make a table listing Guide, p. 115 L2 3 Assess sponges can move from place to from the body of sponges? the cell types and other structures of sponges place only in their larval stages. the sponge out along with their functions. For more help, refer into the water. to Organizing Information in the Skill Handbook. Check for UnderstandingP LS Visual-Spatial Give students a large piece of butcher paper and colored markers. Ask 716 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.1 SPONGES 717 them to drawLS a large sponge P indicating epithelial cells, pore BIOLOGYIOLOGY JOURNAL MEETING INDIVIDUAL NEEDS cells, collar cells, amoebocytes, Section Assessment spicules, and osculum. L2 ELL Sponge Gemmules Gifted 1. Sponges take water into their bodies eventually becoming free-swimming the organism to carry out lifeLS func- Visual-Spatial After observing pre- Visual-Spatial Have your advanced and filter food out of the water. They larvae that later attach to a surface tions more efficiently than a single pared slides of sponge gemmules students reread the description of are filter feeders. and develop into adult sponges. cell can. P with a microscope, have students make fragmentation. Challenge these students 2. Epithelial cells can contract and relax, 4. Amoebocytes carry food from the col- 6. Students’ tables should include the P drawings of gemmules in their journals. to diagram this process and then work thus opening and closing pore cells. lar cells to all other body cells, carry following features and their func- P L1 ELL with other students to review fragmen- 3. Sperm are released in water and travel sperm to eggs for fertilization, and tions: epithelial cells, pore cells, collar P tation. L3 to other sponges. Eggs fertilized inter- produce chemicals that help make up cells, amoebocytes, spicules, and LS nally develop into zygotes in the jelly- the spicules of sponges. osculum. 716 LS like substance between cell layers, 5. Division of labor among cells enables 717 P LS LS P LS P LS

LS SECTION PREVIEW stages of their life cycles. These two Section 26.2 forms are the polyp and medusa, Observing 2 Teach Objectives Section MiniLab 26-1 Figure 26.5. A polyp (PAHL up) is Distinguish the differ- the stage with a tube-shaped body ent classes of cnidarians. 26.2 Cnidarians Watching Hydra Feed Hydras are MiniLab 26-1 Prepare Sequence the stages and a mouth surrounded by tentacles. freshwater cnidarians. They show P in the life cycle of A medusa (mih DEW suh) is the stage the typical polyp body plan and cnidarians. with a body shaped like an umbrella symmetry associated with all mem- Purpose Key Concepts Evaluate the adapta- bers of this phylum. Observe how Students will observe the feeding tions of cnidarians for with tentacles hanging downward. they capture their food. Students will learn about the obtaining food. hat’s the largest structure The hydra has a typical polyp body behavior ofLS hydra. Remind stu- important characteristics of Vocabulary ever built by living organ- form. How do hydras capture their Procedure dents they will be working with food? You can find out by reading the live animals, and to treat them cnidarians. polyp Wisms? Is it the Sears Tower ! Use a dropper to place a hydra Hydra eating copepod medusa in Chicago? How about the Great Inside Story on the next page. into a watch glass filled with gently. Have students wash their nematocyst In cnidarians, one body form may water. Wait several minutes for the animal to adapt to its Planning gastrovascular cavity Pyramid in Egypt? Actually, the hands at the end of the MiniLab. nerve net be more conspicuous than the other. new surroundings. CAUTION: Use caution when working Prepare salt dough for Build- largest structure ever built is the with a microscope and glassware. Process Skills Great Barrier Reef, which extends In jellyfishes, for example, the ing a Model. medusa stage is the dominant body @ Observe the hydra under low-power magnification. sequence, observe and infer, for more than 2000 km along the form. The polyp stage of a jellyfish is # Formulate a hypothesis as to how this animal obtains its hypothesize, draw a conclusion northeastern coast of Australia, small and not very noticeable. In food and/or catches its prey. and it wasn’t built by humans. Teaching Strategies hydras, the polyp stage is dominant, $ Place brine shrimp in a culture dish of freshwater to avoid introducing salt into the watch glass. Hydra are available from bio- 1 Focus This structure was built over many with a small and delicate medusa % Add a drop of brine shrimp to the watch glass while logical supply houses. Add pieces centuries by colonies of small stage. The corals and sea anemones Bellringer marine invertebrate animals continuing to observe the hydra through the microscope. of broken glass to the original have only the polyp stage. ^ Note which structures the hydra uses to capture food. Before presenting the lesson, called corals. Corals and container the day before students display Section Focus Trans- their relatives, jellyfishes Digestion in cnidarians Analysis observe the animals. Hydra will parency 64 on the overhead pro- and sea anemones, all The Great Barrier Cnidarians are predators that cap- 1. Describe how the hydra captures food. cling to glass fragments. Remove jector and have students answer belong to the phylum Reef (above) and ture or poison their prey with nema- 2. Was your hypothesis supported or rejected? the glass and attached hydra with orange clump Cnidaria. tocysts. A nematocyst (nih MAT uh 3. Sequence the events that take place when a hydra a forceps to aid in dispensing the the accompanying questions. coral, Tubastrea sihst) is a capsule that contains a captures and feeds upon its prey. animals. L1 ELL aurea (left) coiled, threadlike tube. The tube may 4. Explain how your observations support the fact that Hatch brine shrimp from eggs 2 hydras have both nervous and muscular systems. be sticky or barbed, and it may con- to 3 days prior to classroom need. tain toxic substances. Nematocysts, Eggs are available from pet shops TransparencyP 64 Cnidarians SECTION FOCUS located in stinging cells, are dis- Use with Chapter 26, or biological supply houses. Follow Section 26.2 What Is a Cnidarian? A cnidarian’s body is made up of two charged like toy popguns, but much prey. Any undigested materials Figure 26.5 directions on container for hatch- cell layers with one body opening. faster, in response to touch or chemi- are ejected back out through the The two basic forms Cnidarians (ni DARE ee uns) are a ing. After hatching, shine a light at The cell layers of cnidarians are cals in the environment. Prey organ- mouth. You can observe a cnidarian of cnidarians are the one edge of the tray—brine shrimp group of marine invertebrates made organized into separate tissues with isms are then taken in for digestion. feeding in the MiniLab on this page. polyp form (a), and LS WORD Origin up of more than 9000 species of jelly- will move toward the light. Use a Hydra the medusa form (b). P specific functions. Cnidarians have a In cnidarians, you can see the ori- tea strainer to remove and rinse cnidarian fishes, corals, sea anemones, and simple nervous system, and both cell gins of a digestive process similar to From the Greek hydras. Cnidarians can be found Mouth shrimp before feeding to hydra. word knide, mean- layers have cells that can contract as that of animals that evolved later. worldwide, but coral species gener- though they were muscles. The two Once captured by nematocysts on the Tentacles b Students will not to able to see ing “nettle,” a plant ally prefer the warmer oceans of the the release of nematocysts from Portuguese with stinging hairs. cell layers of a cnidarian are derived ends of tentacles, prey is brought to man-of-war Gastrovascular LS Cnidarians have South Pacific and the Caribbean. from the ectoderm and endoderm of the mouth by contraction of the ten- the tentacles. cavity stinging tentacles. the embryo. The ectoderm of the tacles. The inner cell layer of cnidar- Binocular microscopes may be Sea anemone Cnidarians have radial symmetry cnidarian embryo develops into a ians surrounds a space called a used, or use a 5 objective on the compound microscope if available. 1 What are some characteristics that are common to Though cnidarians are a diverse protective outer layer of cells, and gastrovascular cavity (gas troh VAS a Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. these animals? Gastrovascular 2 How are these animals adapted to marine life? group, all possess the same basic the endoderm is internal and adapted kyuh lur) in which digestion takes cavity Expected Results body structure, which supports the mainly to assist in digestion. place. Cells adapted for digestion line PolypPolyp Mouth BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES Students will see the tentacles of theory that they had a single origin. Cnidarians display only two basic the gastrovascular cavity and release Medusa All cnidarians have radial symmetry. body forms, which occur at different enzymes over the newly captured Tentacles hydra surround and capture brine shrimp. Food is then pushed by the tentacles into the animal’s 718 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.2 CNIDARIANS 719 mouth.

Cultural Diversity Analysis system directs tentacles to trap and complimenting function. Use the 1. Nematocysts and tentacles work push food into mouth Performance Task Assessment List for Hydra Myth together to capture food. Scientific Drawing in PASC, p. 55. L3 VIDEODISC Intrapersonal Ask students to 2. Student answers will vary depending ELL Biology: The Dynamics of Life Assessment report about the Greek myth deal- on their original hypothesis. Ocean Cnidarians (Ch 31) Portfolio Provide students with ing with the water monster, Hydra. 3. prey organisms brush against the Disc 1, Side 2, 31 sec. prepared slides of cnidarian nematocysts. Students should indicate that Hydra had tentacles, nematocysts are released, Have them observe and diagram these P nine heads. Each time Hercules cut off one prey is captured by tentacles, tenta- P cells under high-power magnification. head, it grew back. Have students identify cles push food into hydra’s mouth !:6Ç" Ask them to explain how nematocysts parts of the myth that are scientifically 4. muscles move the tentacles, nervous illustrate the concept of structure 718 accurate and those that are not. L2 LS 719 LS

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LS Tying to Previous Cnidarians are classified into groups the medusa stage, unless there is no IINSIDENSIDE IINSIDENSIDE partly based on whether or not there medusa stage. Asexual reproduction Knowledge TORY are divisions within the gastrovascu- may occur in either the polyp or Review the Inside Story with stu- S STORY lar cavity, and if there are, how many medusa stage. Cnidarians that remain P dents. Explain that larvae of divisions are present. in the polyp stage, such as hydras, cnidarians produced by sexual Purpose corals, and sea anemones, can repro- reproduction form in the way A Cnidarian Oxygen enters cells directly Students will gain an understand- duce sexually as polyps. Polyps repro- described in the Inside Story. Because of a cnidarian’s simple, duce asexually by a process known as ing of theLS polyp and medusa nidarians display a remarkable variety of colors, shapes forms of cnidarians, and learn Cand sizes. Some can be as small as the tip of a pencil. The two-cell-layer body plan, as shown in budding, as shown in Figure 26.6. Display the Inside Story, no cell in its body is The most common form of repro- about the tentacles and nemato- flowerlike forms of sea anemones are often brilliant shades ever far from water. Oxygen dissolved duction in cnidarians can be illus- Visual-Spatial Ask a group of cysts common to these animals. of red, purple, and blue. Most cnidarians go through both the polyp and medusa stages at some point in their life cycles. in water diffuses directly into the trated by the life cycle of a jellyfish, students to prepare a bul- Teaching Strategies body cells, and carbon dioxide and shown in Figure 26.7 on the next letin board display of the life Critical Thinking How is having poisonous stinging cells an A colony of hydras other wastes diffuse out of the cells page. As you can see, the sexual cycle of a jellyfish. Encourage Emphasize that polyps are ses- advantage for a sessile organism? directly into the surrounding water. medusa stage alternates with the them to use three-dimensional sile forms of cnidarians that live asexual polyp stage, from generation figures if possible. L2 ELL attached to a surface. Nervous regulation in cnidarians to generation. Male medusae release COOP LEARN Be sure that students recog- 1 Tentacles Surrounding the mouth of a cnidarian is 1 2 Polyp A polyp is the Cnidarians have a simple nervous sperm and female medusae release a ring of flexible, tubelike tentacles. Tentacles can be 2 nize that the mouth of a polyp sessile form of a cnidarian. system called a nerve net. A nerve net eggs into the water, where fertiliza- P long as in some jellyfishes, or short as in sea anemones points upward whereas the Polyps have mouths that conducts nerve impulses from all tion occurs. The resulting zygote P and corals, but all are used for capturing food. Some are directed upward. mouth of a medusa points down- jellyfishes have mouth arms that help direct food from parts of the cnidarian’s body, but develops into an embryo, and then Examples of polyps ward. the tentacles to the animal’s mouth. there is no control center such as the into a larva. Recall that a larva is an include sea anemones, brain found in other animals. The intermediate stage in animal develop- corals, and hydras. LS P Visual Learning impulses from the nerve net bring ment. The free-swimming larva VIDEODISC LS Visual-Spatial Provide stu- about contractions of musclelike eventually settles and grows into a STV: Biodiversity dents with prepared slides of cells in the tentacles and body of a polyp, which, in turn, reproduces Loss of Diversity small cnidarian polyps and cnidarian. For example, when asexually to form new medusae. Even Unit 1, Side 1, 3 min. 45 sec. Overview LS medusae. Have students observe 3 Nematocysts touched, a hydra reacts by contract- though these two stages alternate in the slides and make labeled draw- Located primarily at ing its musclelike cells. a cnidarian life cycle, this form the tips of the tenta- of reproduction is not alter- b ings of their observations. L2 !8.N3h`/" cles are stinging cells Reproduction in cnidarians nation of generations as ELL Coral Reefs that contain nema- All cnidarians have the ability to seen in plants because tocysts. When prey reproduce sexually and asexually. cnidarians are diploid ani- Critical Thinking touches the tenta- Sexual reproduction occurs in only mals in both medusa and !8fI4áV-" A sessile organism cannot hunt cles, the stinging cells P release nematocysts, one phase of the life cycle, usually polyp stages. for prey or move away from coiled tubes that 5 Medusa A medusa is the predators. Stinging cells help ses- 5 capture or paralyze free-swimming form of a a the prey. sile organisms get food andP cnidarian. It possesses an escape predation. umbrella-shaped, floating Figure 26.6 LS body with the mouth Nematocyst The main form of reproduction pointing down. before discharge in polyps is budding. During Quick Demo LS this process, small buds grow as extensions of the body Use a microprojector to show wall (a). In some species, such P prepared slides of discharged 4 Bud All cnidarians can repro- Prey as corals, a colony develops nematocysts. duce both sexually and asexu- as the buds break away and ally. A polyp such as hydra settle nearby (b). reproduces asexually by bud- ding. Genetically, a bud is a Nematocyst LS clone of its parent. after ResourceResource discharge ManagerManager 720 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS Section Focus Transparency 64 and Master L1 ELL Internet Address Book BIOLOGYIOLOGY JOURNAL BioLab and MiniLab Worksheets, p. 117 L2 Note Internet addresses that you find useful in the space Budding Hydra P below for quick reference. Visual-Spatial Have students exam- ine prepared slides of budding hydra under a microscope. Ask them to make P scientific drawings of the hydra in their LS biology journals. L2 ELL P P 720 LS 721 P

LS LS P LS

LS Building a Model Female Figure 26.7 Male A In sexual reproduction, allows the colony to dive to lower Figure 26.8 Assessment Kinesthetic Have student In the cnidarian life a male medusa depths or rise to the surface. Other Physalia colonies are groups make clay or salt cycle, a free-swim- releases sperm and polyps hanging from the float have found primarily in Performance Ask students ming larva develops tropical waters, but dough (one part salt, one part a female medusa different functions, such as reproduc- to make a concept map showing into a polyp. The releases eggs. they sometimes drift the different classes of cnidarians flour, one part water) models of structure of this larva tion and feeding. The polyps all into temperate External fertilization and the organisms that make up the life cycle of a jellyfish. Tell gives scientists clues occurs in the water. function together for the survival of waters where they about the origin of the colony. may be washed up each class. Make sure they have them that when they are finished Eggs you will ask the group questions cnidarians. on shore. included the classes Hydrozoa, Scyphozoans are the jellyfishes Scyphozoa, and Anthozoa, and about the jellyfish life cycle. They Sexual will need to use their models Reproduction Have you ever seen a jellyfish like the following organisms: hy- to demonstrate their answers. the one shown in Figure 26.9? Some droids, siphonophores, jellyfishes, Remind students to wear safety jellyfishes are transparent, but others sea anemones, corals. L2 Sperm are pink, blue, or orange. The medusa gogges and an apron when han- Zygote stage is dominant in this class. Like dling modeling materials. L1 D One by one, the tiny medusae other cnidarians, scyphozoans have Reinforcement ELL COOP LEARN break away from the parent B The zygote grows and develops into polyp, and, when they a blastula. The blastula becomes a musclelike cells in their outer cell Be sure students understand that P mature, the cycle begins free-swimming larva. The larva, cov- layer that can contract. When these the Portuguese man-of-war is a Reinforcement again. ered with cilia, swims to an area suit- cells contract together, the medusa colonial hydrozoan. able for attachment and settles. MakeP a transparency of Figure contracts, which propels the animal P 26.7 with just the figures. White through the water. The fragile and Visual Learning out the captions before you make sometimes luminescent bodies of jel- coral reefs that provide food and LS C In the asexual phase, a polyp lyfishes can be beautiful, but most shelter for many other marine Figure 26.9 Naturalist Show students your transparency and number grows and begins to form buds people know about jellyfishes more species. When a coral polyp dies, the The jellyfish examples of a variety of pre- eachLS figure. Ask students to make that become tiny medusae. As P Larva by their painful stings. Jellyfishes can limestone skeleton it leaves behind Chrysaora hysoscella served sponges and cnidarians.LS a list of corresponding numbers the buds build up, the polyp has the common Asexual be found everywhere in the oceans, adds a tiny piece to the structure of Have them make a chart listing on a sheet of paper and describe resembles a stack of plates. name compass jelly- Reproduction from arctic to tropical waters, and the reef. The living portion of a coral the type of animal, structural fea- each stage. L2 fish due to the radiat- have been seen as deep as 1000 m. reef is a thin, fragile layer that grows ing brown lines on its tures they used to identify the LS The gastrovascular cavity of scypho- on top of the skeletons left behind by medusa. animal, and adaptations the ani- zoans has four internal divisions. mal has that make it suited to its environment. L1 ELL Most anthozoans build coral reefs Anthozoans are cnidarians that VIDEODISC exhibit only the polyp form. All TheP Secret of Life Diversity of Cnidarians the ocean’s surface as well as colonies anthozoans have many divisions in P Life Cycle of a that form swimming medusae. their gastrovascular cavities. Jellyfish Most of the 9000 described species Hydrozoans have open gastrovascu- Sea anemones are anthozoans that CD-ROM of cnidarians belong to one of three lar cavities with no internal divisions. live as individual animals. Sea Biology: The classes: Hydrozoa, Scyphozoa, and It’s difficult to understand how the !7;E`F"LS anemones are thought to live for cen- Dynamics LSof Life Anthozoa. organism shown in Figure 26.8 turies. Some tropical sea anemones Video: Ocean CnidariansP could be a closely associated group of may have a diameter of more than a Disc 4 Most hydrozoans form colonies individual animals. The Portuguese meter. Sea anemones can be found in The class Hydrozoa includes two man-of-war, Physalia, is an example tropical, temperate, and arctic seas. Video: Coral Reefs ResourceResource groups—the hydroids, such as hydra, of a siphonophore hydrozoan colony. Corals are anthozoans that live in Disc 4 LS ManagerManager and the siphonophores, including the Each individual in a Physalia colonies of polyps in warm ocean Portuguese man-of-war. Most colony has a different function that waters around the world. They Basic Concepts Transparency hydroids consist of branching polyp helps the entire organism survive. secrete cuplike calcium carbonate 47 and Master L2 ELL colonies that have formed by bud- For example, just one individual (limestone) shelters around their soft Reinforcement and Study ding. The siphonophores include forms a large, blue, gas-filled float. bodies for protection. Colonies of Guide, p. 116 L2 floating colonies that drift about on Regulation of the gas in the float many coral species build the beautiful Content Mastery, p. 130 PL1 VIDEODISC Laboratory Manual, 722 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.2 CNIDARIANS 723 STV: Biodiversity pp. 187-188 L2 Coral Reef; Gulf of PortfolioPortfolio MEETING INDIVIDUAL NEEDS BIOLOGYIOLOGY JOURNAL Aqaba P LS !7Q/j&" P Treating Jellyfish Stings Ask students to demonstrate the first aid Learning Disabled Coral Art Interpersonal Ask a group of students procedures and explain why each procedure Visual-Spatial Ask a group of stu- Visual-Spatial Ask students to design Gorgonian Corals and Fish to contact first aid stations on public is performed. Students should write sum- dents to visit a saltwater aquarium, a postage stamp that will commemo- LS P P P beaches where jellyfishes are common. Have maries for their portfolios. L3 ELL P either at a pet shop, restaurant, zoo, or rate coral animals’ importance, and beauty. !7Q*t+" LS them prepare a report on the treatment COOP LEARN marine park, and take photographs for a Give students colored markers and plain given to victims of the stings of these animals. photo essay about sea anemones. You white paper. Remind them that little can P P might also provide a preserved anemone be written on a postage stamp. Provide LS P P LS LS LS for them to dissect. L2 ELL photos of corals. Have students place their 722 P designs in their journals. L2 ELL 723 LS LS LS P LS P LS P LS P LS

LS LS Problem-Solving Lab 26-2 previous generations. Coral reefs Figure 26. 11 Problem-Solving Lab 26-2 Interpreting Data grow very slowly, about 2 mm per Sponges and cnidarians evolved from a 3 Assess P Problem-Solving Lab 26-2 Hydrozoans year. It took centuries to form the common ancestor early in geologic time. Sponges probably were the first to appear, 2700 species Purpose reefs found today in tropical Check for Understanding What ocean conditions limit the followed by the classes of cnidarians. Students will study two graphs number of coral species? All Graph A and subtropical oceans. Find Have students draw a hydra cross that show how certain abiotic fac- corals that build reefs have a mutu- out more about the fragility of section and add arrows to show LS 120 tors influence the location of alistic symbiotic relationship with 105 coral reefs by reading the Scyphozoans the exchange of oxygen and zooxanthellae. Zooxanthellae 90 Biology & Society feature at the ANIMALS 200 species coral species. 75 carbon dioxide and how food within the coral carry on photosyn- end of this chapter. Corals that thesis and provide some nutrients 60 reaches all cells. L1 ELL Process Skills 45 form reefs are known as hard to the coral. Animals caught by the 30 15 corals. Other corals are known think critically, interpret data, coral provide some nutrients to Number of Species Reteach 0 as soft corals because they do compare and contrast, make and these protists. 0306090 Anthozoans Interpersonal DrawP a foot- Depth (m) not build such structures. use graphs Analysis 6200 species ball field on the chalkboard. Graph A shows the number A coral polyp extends its of species present in coral reefs at tentacles to feed, as shown in Divide the class into two teams. Teaching Strategies Graph B certain depths. Graph B shows the Figure 26.10. Although coral Ask questions about cnidarians. If Review the meaning of sym- Poriferans number of species present at dif- 120 reefs are often found in rela- 5000 species a student answers correctly, biosis and mutualism, abiotic and LS ferent temperatures. All reef-build- 105 tively shallow, nutrient-poor advance the ball 10 yards towards biotic factors. ing coral species have zooxanthel- 90 P 75 waters, the corals thrive because that team’s goalpost. If the Suggest to students that they lae. The effects of abiotic factors 60 Protists on organisms are usually related. 45 they form a symbiotic relation- answer is not correct, the ques- analyze each graph separately. For example, temperature and lev- 30 ship with tiny organisms called PRECAMBRIANPALEOZOIC MESOZOIC CENOZOIC PRESENT 15 tion goes to the other team. The However, point out that abiotic Number of Species P els of illumination in an ocean vary 0 zooxanthellae, photosynthetic team that reaches its goalpost factors are interrelated. with depth. 018222630 LS protists. The zooxanthellae L2 COOP LEARN Temperature ( C) The earliest known cnidarians date first wins. Thinking Critically (zoh oh zan THEH lee) supply Origins of Sponges Thinking Critically oxygen and food to the corals to the Precambrian Era, about 630 mil- P 1. Identify the abiotic and biotic factors being studied in this and Cnidarians lion years ago. Because cnidarians are Extension 1. abiotic—ocean depth, tem- ocean environment. while using carbon dioxide and waste LS As shown in Figure 26.11, sponges soft-bodied animals, they do not pre- perature; biotic—coral 2. In Graph A, what seems to be the correlation between materials produced by the corals. Have students write about the represent an old animal phylum. The serve well as fossils, and their origins different ways that corals obtain 2. The number of coral species number of coral species present and depth? Use actual These protists are primarily responsi- numbers from the graph in your answers. earliest fossil evidence for sponges are not well understood. The earliest food. Ask them to describe how decreases rapidly until about ble for the bright colors found in LS 3. In Graph B, what seems to be the correlation between coral reefs. Because the zooxanthellae dates this group to the Paleozoic Era, coral species were not reef builders, each of these food-getting strate- 20 m, when it begins to level P number of species present and the temperature? Use are free-swimming, they sometimes about 700 million years ago. so reefs cannot be used to date early gies are used during a 24-hour off. actual numbers from the graph in your answer. leave the corals. Corals without these Scientists infer that sponges may cnidarians. The larval form of cnidar- cycle. 3. Temperatures between 22°C 4. Bleaching occurs when coral polyps expel their zooxan- protists often die. You can find out have evolved directly from a group of ians resembles protists, and because thellae. Bleaching has been observed when water temper- and 30°C seem to be more how corals respond to changing envi- flagellated protists that today resem- of this, scientists consider cnidarians ature exceeds 35ºC. How might depth of coral be related ble the collar cells of sponges. to have evolved from protists. favorable to coral diversity. to bleaching? ronmental conditions in the Problem- AssessmentLS Fewer species survive at tem- Solving Lab. Performance Ask students peratures below 22°C. Section Assessment to make a travel brochure for 4. Zooxanthellae require sun- Figure 26.10 ab tourists who wish to see cnidari- light in order to carry out Corals feed by Understanding Main Ideas destruction of a large coral reef to have on ans. They should include all photosynthesis. The corals extending their ten- 1. Compare the medusa and polyp forms of other ocean life? tacles outside their cnidarians. cnidarian groups in their bro- live near the surface of the limestone cups (a), 2. Diagram the reproductive cycle of a jellyfish. SKILL REVIEWEVIEW chure. Use the Performance Task ocean. Temperature decreases but if they are threat- 3. What are the advantages of a two-layered body 6. Making and Using Tables In a table, Assessment List for Booklet or ened, they can as depth increases. In tropical in cnidarians? distinguish the three main groups of cnidarians, Pamphlet in PASC, p. 57. L2 regions, corals that live close retreat back into the 4. How are corals different from other cnidarians? list their characteristics, and give examples cups (b) until danger to the surface are more likely of a member from each group. For more has passed. Thinking Critically help, refer to Organizing Information in the to be exposed to high tem- 5. Coral reefs are being destroyed at a rapid Skill Handbook. peratures and, therefore, are rate. What effect would you expect the 4 Close more at risk for bleaching. Activity

724 26.2 CNIDARIANS 725 Have students observe the move-P ments of a live hydra in a deep- well 35 mm projector slide on a slide projector. Ask them to Assessment Section Assessment review the adaptations ofLS the Performance Have students 1. Polyps, the sessile stage of cnidarians, have life functions. hydra to its environment. L1 VIDEODISC research how the building of a coral a mouth that points upward. The medusa, 4. Corals secrete calcium carbonate shelters The Infinite Voyage: To the Edge skeleton may also benefit from the pres- the free-swimming stage, has a mouth around their bodies. of the Earth ence of algae. L2 pointing downward. 5. Other ocean life will be destroyed Exploring the Galapagos Islands (Ch. 4) 2. Make sure students follow the steps shown because the marine life of the area is in Figure 26.7. dependent upon coral reefs. !7KVF" 3. The cell layers of cnidarians are organized 6. Make sure students have listed the charac- into separate tissues, which enable an teristics and examples of the three cnidar- 724 animal to be more efficient in carrying out ian groups. 725 P P

LS LS SECTION PREVIEW diseases in other animals, among Section 26.3 them frogs and humans. The most Problem-Solving Lab 26-3 Predicting 2 Teach Objectives Section Problem-Solving Lab 26-3 commonly studied flatworms in biol- Distinguish the ogy classes are the free-living pla- adaptive structures of 26.3 Flatworms Which Came First? There are three classes of flatworms. parasitic flatworms and narians (class Turbellaria). You can Two classes are parasitic and the third is free-living. Free-liv- Problem-Solving Lab 26-3 free-living planarians. Prepare learn about the evolutionary relation- ing flatworms are grouped in the class Turbellaria. Trematoda P Explain how parasitic ships among these classes of flat- and Cestoda are parasitic classes. These two classes often Key Concepts flatworms are adapted Purpose to their way of life. worms in the Problem-Solving Lab on have humans or some other mammal as one of their hosts. Students are to determine which In this section, students will magine the ultimate couch potato this page. Flatworms range in size Vocabulary Analysis class of flatworms evolved first. study the adaptive structures pharynx among living organisms—a worm that from 1 mm up to several meters. Diagrams A, B, and C show a possible evolutionary rela- LS of parasitic flatworms and pla- regeneration never has to move using its own power, There are approximately 14 500 tionship among the three classes. The class at the bottom of scolex I Process Skills narians. They will learn about is always carried by another organism, is species of flatworms found in marine each diagram can be assumed to have evolved first. proglottid think critically, predict how these worms are adapted surrounded by food that is and freshwater environments and in to their environments. moist habitats on land. A C already digested, and never Turbellaria Trematoda Cestoda Turbellaria Teaching Strategies has to expend much energy. Planning Feeding and digestion Students may need additional This describes a parasite B Purchase single-edged razors in planarians Trematoda Cestoda help in understanding the nature called a tapeworm. The A planarian feeds on dead or slow- of the three diagrams. and spring water for the parasitic way of life has moving organisms. It extends a tube- Cestoda Trematoda Student groups of 2 or 3 may BioLab. many advantages. like, muscular organ, called the work well for this activity. Tapeworm pharynx (FAH rinx), out of its mouth. Turbellaria scolex Enzymes released by the pharynx Thinking Critically 1 Focus Magnification: 11 begin digesting food outside the ani- Thinking Critically Diagram B is correct. Student Magnification: 80 mal’s body. Then food is sucked into One of the three evolutionary patterns is correct. Pick the explanations may vary but the the gastrovascular cavity, where food one that you consider to be correct. Defend your answer by Bellringer explaining your reasoning. Include in your answer why the main concept that should be particles are broken up. Cells lining Before presenting the lesson, dis- other two could not be correct. explained is: Free-living classes of the digestive tract obtain food by play Section Focus Trans- the flatworms evolved first. This What Is a Flatworm? The least complex worms belong phagocytosis. Food is thus digested class then evolved into the para- parency 65 on the overhead to the phylum Platyhelminthes, in individual cells. projector and have students To most people, the word worm Figure 26.12. These flatworms are system enables a planarian to respond sitic forms. It would be difficult answer the accompanying ques- describes a long, spaghetti-shaped acoelomates with thin, solid bodies. Nervous control in planarians to the stimuli in its environment. to explain how a parasitic worm tions. L1 ELL animal. Many animals have this gen- The most well-known members of Some flatworms have a nerve net, Most of a planarian’s nervous system could evolve first with such a eral appearance, but now it is under- this phylum are the parasitic tape- and others have the beginnings of a is located in its head—a feature com- complex life cycle. If one assumes stood that many wormlike animals worms (class Cestoda) and flukes central nervous system. A planarian mon to other bilaterally symmetrical that flatworms evolved before can be classified into different phyla. (class Trematoda), which cause has a nervous system that includes animals. mammals, then it would be Transparency 65 FlatwormsP SECTION FOCUS Use with Chapter 26, Section 26.3 two nerve cords that run the length impossible for the parasitic Ganglia ab c of its body, as you can see in Figure 26.13 worms to have had any host Head Figure 26.12 Figure 26.13, sensory pits that detect Eyespots The simple nervous available to them. Tapeworms are chemicals and movement in water, system of a planarian parasites that invade LS and eyespots that detect light and Nerve cord enables it to make and live in host P dark. At the anterior end of the nerve adjustments to stim- organisms (a). Flukes uli in its environment. Assessment usually require two cord is a small swelling called a gan- Knowledge Ask students hosts in a complex glion. Located in the head, the gan- to describe those traits that flat- life cycle (b). glion receives messages from the eye- Tapeworm worms do and do not share with Planarians are not spots and sensory pits, then commu- LS parasitic, nor do they nicates with the rest of the body cnidarians. Use the Performance cause diseases (c). Muscle cells along the nerve cords. Messages from Task Assessment List for Making 1 This tapeworm is a parasite. What do you think the hooklike structures at the head of the tapeworm are used for? Observations and Inferences in 2 What is one advantage and one disadvantage of a parasitic the nerve cords trigger responses in a way of life? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. planarian’s muscle cells. The nervous PASC, p. 17. L2

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES 726 26.3 FLATWORMS 727 Magnification: 30 Magnification: 22

PROJECT PortfolioPortfolio ResourceResource Planarian Behavior Marine Flatworms P ManagerManager VIDEODISC Kinesthetic Have students design Linguistic Have students visit a The Secret of Life Section Focus Transparency 65 experiments that explore planarian marine aquarium, zoo, or pet store Flatworm Cross Section and Master L1 ELL behavior. They might investigate specializing in saltwater species to Laboratory Manual, responses to food, touch, heat, cold, or research marine flatworms. Have them LS pp. 189-190 L2 other variables. Make sure they plan write a summary of their findings to P experiments in which there is only one include in their portfolios. L2 ELL P P !7;EtH" variable, a control, and quantitative data P 726 to be collected. L2 ELL 727 LS P LS LS LS PP P P LS P LSLS LS LS LS Concept Development Reproduction in planarians Diversity of Flatworms NSIDE NSIDE Display several preserved flat- NSIDE NSIDE II II Magnification: 42 Study the body of a planrian in the Planarians are free-living flat- Inside Story. How does a planarian worms. Ask students to observe STORY STORY worms. Tapeworms and flukes are the worms and list their similari- P reproduce? Like many of the organ- parasitic flatworms. These parasites isms studied in this chapter, most ties and differences. Have them Purpose live in the bodies of many vertebrates speculate which ones are para- flatworms are hermaphrodites. including dogs, cats, cattle, monkeys, A Planarian sites and ask them to explain Students will study the structures During sexual reproduction, individ- and people. and adaptationsLS of planarians. f you’ve ever waded in a shallow stream and turned over ual planarians exchange sperm, which their choices. L2 ELL Isome rocks, you may have found tiny, black organisms travel along special tubes to reach the Tapeworm bodies have sections Teaching Strategies stuck to the bottom of the rocks. These organisms were most eggs. Fertilization occurs internally. Some adult tapeworms that live in WORD Origin likely planarians. Planarians have many characteristics com- The zygotes are released in capsules Assessment Allow students to examine live animal intestines can grow to more AssessmentP mon to all species of flatworms. The bodies of planarians are scolex planarians or a prepared slide of a into the water, where they hatch into than 10 m in length. The body of a Knowledge Ask students flat, with both a dorsal and a ventral surface. All flatworms From the Greek planarian. Have them make tiny planarians. tapeworm is made up of a head and word skolek, mean- to explain how regeneration of have bilateral symmetry. drawings of their observations. Planarian Planarians can also reproduce individual repeating sections called ing “worm.” missing body parts in planarians asexually. When a planarian is dam- L1 ELL proglottids, shown in Figure 26.14. A scolex is the can also be a Pform of asexual Critical Thinking Why is having knob-shaped head LS aged, it has the ability to regen- The knob-shaped head of a tape- reproduction. Students should be a head an advantage to a erate, or regrow, new body parts. of a tapeworm. Visual Learning worm is called a scolex (SKOH leks). able to explain that when a pla- swimming animal? 2 Eyespots Eyespots are Regeneration is the replacement or Have students use the art in sensitive to light and A proglottid (proh GLAH tihd) is a narian is cut into two halves, each P regrowth of missing body parts. the feature to label the pla- enable the animal to detachable section of a tapeworm that half can regenerateLS the missing half respond to the amount Missing body parts are replaced contains muscles, nerves, flame cells, narian they draw. of light present. through mitosis. If a planarian is cut through mitosis. This results in two Point out various structures of 1 Head Flatworms have a and male and female reproductive new worms that are genetically iden- clearly defined head. The horizontally, the section containing organs. Each proglottid may contain the planarian. As you mention the head will grow a new tail, and the tical to the original worm. In asexual LS head senses and responds 3 Sensory pits Located on the sides up to 100 000 eggs, and some tape- each structure, have students to changes in the tail section will grow a new head. reproduction, a parent produces off- P of the head, sensory pits are used to worms consist of 2000 proglottids. identify the function of the environment. detect food, chemicals, and move- Thus, a planarian that is damaged or spring that are genetically identical structure. ments in the environment. cut into two pieces may grow into Figure 26.14 Magnification: 29 to the parent. two new organisms—a form of asex- The scolex is covered with hooks a Critical Thinking ual reproduction. Go to the BioLab at and suckers that attach to the The BioLab at the AsLS a swimming animal moves for- 6 Pharynx The pharynx is the end of this chapter to observe intestinal lining of the host (a). end of the chapter INVESTIGATE Mature proglottids full of ward, the head encounters new a muscular tube that can regeneration in planarians. can be used at this be extended outside the fertilized eggs are shed (b). information first. As most sen- animal’s body through its 4 Flame cells Excess water is removed Feeding and digestion Eggs hatch when they are point in the lesson. sory organs are located in the mouth. It is used to suck from the planarian’s body by a system in parasitic flatworms eaten by a secondary host. food into the planarian’s of flame cells. The water from flame head, this information is relayed Although the basic structure of a b to the rest of the animal, enabling gastrovascular cavity. cells collects in tubules and leaves the Note that the mouth is body through pores on the body surface. parasitic flatworm is similar to that of it to react appropriately. a body opening located Mouth Flame cells are so named because the a planarian, it is adapted to obtaining in the midsection of constant movement of the cilia inside nutrients from inside the bodies of flame cells resembles the flickering of the planarian. Extended one or two hosts. Recall that a para- pharynx a candle’s flame. CD-ROM Quick Demo site is an organism that lives on or in another organism and depends upon Biology: The Dynamics Place a live planarian in water of Life Cilia that host organism for its food. Digestive tract in a 35mm deep-well slide that Parasitic flatworms have mouthparts BioQuest: Biodiversity Park can be projected through a with hooks that keep the worm Discs 3, 4 slide projector. Ask students to firmly attached to the insides of its observe how the worm moves. 5 Cilia Hairlike cilia are host. Parasitic flatworms do not have Point out that the planarian has located on the ventral complex nervous or muscular tissue. Flame a head area. Remind them that surface of planarians. Because they are surrounded by Cilia help the worm to cell sponges do not have a head Excretory 3 Assess pull itself along. nutrients, they do not need to move and ask the survival advantage system to seek out or find food. P Magnification: 35 of having a head area on the Check for Understanding body. L1 ELL 728 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.3 FLATWORMS 729 Naturalist Ask students to make and fill out a table about flatworms with the follow- LS MEETING INDIVIDUAL NEEDS BIOLOGYIOLOGY JOURNAL ing headings: symmetry, habitat, P food-getting, nervous control, Learning Disabled Flatworm Life Cycles digestion, reproduction, free- VIDEODISC Naturalist Provide students with Mapping Worm Parasites Visual-Spatial Have students pre- living or parasitic, examples. L2 outlines of planarians. Ask students The Secret of Life pare diagrams that show the life LS Six Kingdoms Visual-Spatial Give students a blank to use one outline to show the symmetry map of the world and have them cycles of common human flatworm para- P of the planarian as well as its anterior and color code it for where worm parasites sites. College-level invertebrate zoology posterior ends and dorsal and ventral textbooks are excellent resources for such affect humans. Ask students to list pre- P sides. Have students use the Inside Story as P diagrams. Ask students to put these dia- P !7;58D" ventive measures that could be taken to a model to show individual body systems eliminate each parasite. L2 ELL grams in their journals. L2 ELL 728 LS of planarians. L1 ELL 729P LS LS LS P P P LS

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LS Reteach B Fluke eggs pass out of SECTION PREVIEW In their groups, have some stu- A Adult flukes are the body with human Section 26.4 Section Objectives dents draw and label the struc- about 1 cm long wastes. If the eggs and live in the blood reach freshwater, Compare the structural tures of a planarian. Have other adaptations of round- vessels of the human they hatch. students diagram the life cycle of intestine. 26.4 Roundworms worms and flatworms. Taenia solium or the Schistosoma Identify the charac- Prepare fluke. L2 ELL COOP LEARN Human host Adult flukes teristics of four Eggs hatch roundworm parasites. Key Concepts P Vocabulary Students will compare and con- Extension C Eggs hatch into free- ave you ever been to the vet- none E When humans walk swimming larvae that trast the structural adaptations of InterpersonalP Ask a group of erinarian to have your dog through water with enter their snail hosts. tested for heartworms? roundworms and learn about the students to interview a vet- bare feet or legs, H characteristics of the round- the fluke larvae Larva that Perhaps you recall being warned not erinarian and reportLS on the pro- worms Ascaris, Trichinella, hook- cedures for diagnosing and bore through the D Larvae develop inside the infects inter- to eat uncooked pork products. P skin, enter the mediate host worms, and pinworms. treating parasitic worms in pets. snail and reproduce. New Flatworms are not the only type of LS bloodstream, and larvae leave the snail and worms that can cause harm to L2 ELL pass to the intestine, enter the water. where they mature. humans and other vertebrates. It Planning Fertilized eggs pass has been estimated that about Obtain a live vinegar eel cul- LSAssessment out of the intestine one-third of the world’s human ture for the Quick Demo. P Assessment and the cycle begins again. Snail host population suffers from problems Knowledge Have students caused by roundworms. assume they are preparing an Larva that Dog heartworms exhibit about planarians for a infects final host 1 Focus children’sP LS museum. Ask students to draw the worm, label its parts, Figure 26.15 Bellringer and discuss its body systems in The Schistosoma fluke requires two The life cycle of a fluke Blood flukes of the genus Before presenting this lesson, simple terms. L1 ELL hosts to complete A fluke is a parasitic flatworm that Schistosoma, shown in Figure 26.15, Most roundworm species are free-liv- display Section Focus Trans- LS its life cycle. What Is a Roundworm? invades the internal organs of a ver- cause a disease in humans known as ing, but many are parasitic, including Figure 26.16 parency 66 on the overhead pro- tebrate such as a human or a sheep. It schistosomiasis. Schistosomiasis is Roundworms belong to the phylum those shown in Figure 26.16. In fact, Parasitic roundworms jector and have students answer P obtains its nutrition by embedding common in countries where farmers Nematoda. They are widely distrib- virtually all plant and animal species include Ascaris (a), the accompanying questions. 4 Close Trichinella (b), itself in organs where it feeds on grow rice. Farmers must work in uted, living in soil, animals, and both are affected by parasitic roundworms. hookworms (c), L1 ELL Activity cells, blood, and other fluids of the standing water in rice fields during freshwater and saltwater environ- Roundworms are tapered at both pinworms (d), and Show students a selection of one- host organism. Flukes have a com- planting and harvesting. Blood flukes ments. More than 12 000 species of ends. They have a thick outer cover- nematodes (e) that plex life cycle that may include one, frame cartoons aboutLS animals by are common where the secondary roundworms are known to scientists. ing that protects them from being affect plants. two, or more hosts. host, snails, also are found. TransparencyP 66 Body Plans SECTION FOCUS Use with Chapter 26, P Section 26.4 Gary Larson. Ask them to design Magnification: Magnification: 286 e a cartoon about planarians that is b 166 humorous and scientifically accu- c Section Assessment rate. L2 ELL a LS LS Understanding Main Ideas Thinking Critically 1. Diagram and label the structures of a planarian. 5. Examine the life cycle of a parasitic fluke, and P ResourceResource 2. Why don’t tapeworms have a digestive suggest ways to prevent infection on a rice farm. P ManagerManager system? Hydra 3. What is the adaptive advantage of a nervous SKILL REVIEWEVIEW system to a free-living flatworm? 6. Observing and Inferring What can you infer Reteaching Skills Trans- Ascaris 4. How is the body of a tapeworm different about the way of life of an organism that has no LS parency 39 and Master P from that of a planarian? mouth or digestive system, but is equipped with L1LS ELL a sucker? For more help, refer to Thinking

Reinforcement and Study Critically in the Skill Handbook. 1 The drawings show longitudinal sections of two different animals. How does food enter and waste exit each animal? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2 Ascaris is a pseudocoelomate (has a fluid-filled body cavity). Guide, p. 117 L2 What is the advantage of this characteristic? Content Mastery Magnification: 250 LS P BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES p. 131 L1 730 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS d Magnification: 4

MEETING INDIVIDUAL NEEDS PortfolioPortfolio LS Section Assessment 1. MakeP sure studentsP have labeled the 4. Tapeworms have mouthparts with Planarians have a head with eyespots. Gifted/Visually Impaired/ Roundworm Data Table head, eyespots, sensory pits, cilia, hooks while planarians have a pharynx They also have digestive tissues. Learning Disabled Naturalist Have students construct flame cells, mouth, and pharynx. that can extend out of the mouth. 5. Workers could wear boots and gloves. Kinesthetic Have gifted students a table that lists the names of each 2. They live in intestines surrounded by Tapeworms do not have complex ner- Human wastes should be kept out of make clay models of the worms roundworm discussed in the left column. P digestedLS food. LS vous or muscular tissue, whereas pla- the water. studied in this section. Provide these Have students sketch the roundworm in 3. It enables the worm to sense food and narians have these tissues. Tapeworms 6. This organism would most likely be a models to students who have visual the second column, describe its habitat in P the third column, and explain how the appropriate habitat as it swims. have a knob-shaped head and a body parasite that attaches to its host by problems or learning disabilities for use P made up of segments called proglot- means of a sucker and uses food that in studying these organisms. L1 worm affects humans in the fourth col- 730 LS tids but have no digestive system. the host has already digested. umn. L2 P 731 LS LS LS

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LS LS 2 Teach BIOLOGYIOLOGY JOURNAL digested by their host organisms. On Diversity of Roundworm parasites of other a flat surface, roundworms look like organisms Problem-Solving Lab 26-4 Interpreting Scientific Roundworms Problem-Solving Lab 26-4 Illustrations Roundworm Symmetry MiniLab 26-2 tiny, wriggling bits of sewing thread. Nematodes can infect and kill pine Visual-Spatial Provide P They lack circular muscles but have Roundworms are found as para- trees, cereal crops, and food plants How can the pork worm parasite be controlled? students with an outline pairs of lengthwise muscles. As one sites in most organisms on Earth. Purpose such as potatoes. They are particu- Trichinella spiralis, the pork worm, is contracted when drawing of a roundworm. WORD Origin muscle of a pair contracts, the other Approximately half of the described Students will observe the larval larly attracted to plant roots. About humans eat raw or undercooked pork products. Trichinella muscle relaxes. This alternating con- roundworm species are parasites, and Have students add a line to stage of the pork worm embed- 1200 species of nematodes cause dis- Analysis the diagram to show the bilat- LS From the Greek traction and relaxation of muscles about 50 species infect humans. eases in plants. They also infect fungi ded in muscle tissue of its host. word trichinos, This diagram shows the life cycle of the pork worm. eral symmetry of the worm. causes roundworms to move in a and form symbiotic associations with meaning “made of Roundworm parasites invade A cyst is a protective covering that encloses the dormant Ask students to label the Process Skills thrashing fashion. bacteria. Soil nematodes invade roots larval stage. hair.” Trichinella humans through a variety of worm’s anterior, posterior, species are slender, Roundworms have a pseudo- of plants grown for food, as you can observe and infer, measure in SI methods P hairlike, round- coelom and are the simplest animals see in Figure 26.17, and cause a slow Life Cycle of a Pork Worm dorsal, and ventral areas. Teaching Strategies worms. with a tubelike digestive system. Ascaris mainly infects children who decline of the plant. Events 1 Pig is slaughtered Events in L1 ELL Prepared slides of pork worm Recall that a pseudocoelom is a body swallow eggs when they put their in Pigs Humans are available from biological sup- cavity partly lined with mesoderm. soiled hands into their mouths or eat 2 Uncooked pig scraps with 6 Humans eat pork with ply houses. Unlike flatworms, roundworms have vegetables that have not been washed. larvae are fed to pigs. cysts. LS Figure 26.17 P Certain larvae will appear as two body openings—a mouth and an The eggs hatch in the intestines, move Roundworms that are plant parasites 3 Larvae are released from 7 Larvae are released from round segments due to the plane anus. The free-living species have to the bloodstream, and then to the usually enter the roots, forming cysts cysts during digestion. cysts during digestion. 3 Assess through which the slice was made well-developed sense organs, such as lungs, where they are coughed up and that affect the plant’s ability to absorb 4 Larvae mature, mate, 8 Larvae mature, mate, eyespots, although these are reduced swallowed to begin the cycle again. water. and produce thousands and produce thousands Check for Understanding in preparing the slide. of new larvae. of new larvae. in parasitic forms. Hookworms commonly infect Have studentsLS write true or false Expected Results 5 Larvae travel in blood 9 Larvae travel in blood humans in warm climates where peo- questionsP relating to round- Students will not be able to see ple walk on contaminated soil in bare stream to muscles and stream to muscles and form cysts. form cysts. worms. Review and explain the pork worm larvae without the aid feet. Hookworms cause people to feel Magnification: 195 correct answers. L2 of a microscope. Size of the lar- MiniLab 26-2 Observing weak and tired due to blood loss. vae will be close to 100 mm. Pinworms are the most common LS parasites in children. Pinworms Thinking Critically Reteach Analysis Observing the Larval Stage of a Pork Worm You can observe invade the intestinal tract when chil- 1. Would it be practical or impractical to disrupt the pork Have students play bingo with a 1. microscopic, round, like a hot the larval stage of a pork worm dren eat something that has come in worm life cycle: At step 2? At step 4? At step 6? At step 16-square card with the name of 9? Explain your answers. dog, spiral (Trichinella spiralis) embedded contact with contaminated soil. a worm in each square. Read a 2. Why doesn’t the arrow return to the top of the diagram 2. Pork worm larvae are micro- within the muscle tissue of its host. Female pinworms lay eggs near the list of statements and have stu- It will look like a curled up hot after step 9 as it does after step 5? P scopic and cannot be identi- dog surrounded by muscle tissue. anus, and reinfection is common dents play bingo. L2 fied by a visual inspection. because the worms cause itching. Pork Worm 3. Samples of muscle tissue can Procedure Trichinella worms cause a disease Extension be taken and viewed under a ! Examine a prepared slide of pork worm larvae under the called trichinosis. These worms enter microscope. low-power magnification of your microscope. the body in undercooked pork. Find Section Assessment Ask students to LSdo a videotape @ Locate several larvae by looking for “spiral worms out what these roundworms look like report on parasitic roundworms Understanding Main Ideas Make a list of precautions that could be enclosed in a sac.” All other tissue is muscle. in the MiniLab on this page. in humans. L3 # Estimate the size of the larva in µm. 1. Compare the body structures of roundworms taken to help prevent its continued Trichinosis is not as common in the and flatworms. spread. Assessment $ Diagram one larva. Indicate its size on the diagram. P United States as it once was because 2. Why do parents teach children to wash their Portfolio Have students SKILL REVIEWEVIEW Analysis of stricter meat inspection standards. hands before eating? Assessment put their diagrams in their portfo- 3. Describe the method of infection of one human 6. Making and Using Tables Make a table of 1. Describe the appearance of a pork worm larva. However, Trichinella worms are Portfolio Ask students to lios. Use the Performance Task microscopic and may not be seen dur- roundworm parasite. the characteristics of four roundworm parasites, Assessment List for Science Port- 2. Why might it be difficult to find larva embedded 4. Compare how Ascaris and Trichinella are indicating the name of the worm, how it is write a paragraphP LSto explain how in muscle when meat inspectors use visual checking ing a visual inspection. Trichinosis contracted. contracted, the action of the parasite in the the roundworm diseases they stud- folio in PASC, p. 105. L1 P methods in packing houses to screen for pork worm can be controlled by cooking pork body, and means of prevention. For more help, ied might be prevented. L2 P contamination? long enough to kill any worms that Thinking Critically refer to Organizing Information in the Skill 3. Suggest what inspectors might do to help detect may be present. You can learn more 5. An infection of pinworms is spreading Handbook. pork worm larvae. LS Problem-Solving Lab 26-4 about controlling trichinosis in the to children who attend the same preschool. P LS Problem-Solving Lab on the next page. 4 Close LS Purpose 732 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.4 ROUNDWORMS 733 Activity Students will study a diagram of Set up stations around the class- the pork worm life cycle. P LS room with photos or slides of the P Thinking Critically Assessment Process Skills Section Assessment roundworms studied. Have stu- 1. impractical, unless there is a drug that Skill Ask students to describe any dif- apply concepts, think critically, dents identify each worm. L2 can be given to the pig to destroy the ferences in the life cycle of the pork worm 1. Roundworms have a pseudocoelom and of good hygiene. ELL interpret scientific diagrams adult worm; practical, make sure all two body openings. Flatworms are acoelo- 4. Ascaris is contracted by eating food LS LS when in a pig host compared with its life Teaching Strategies scraps are cooked before feeding them cycle when in a human host. They are essen- mate with only one body opening. contaminated by Ascaris. Trichinella is to a pig; practical, advise consumers tially alike. L2 2. It is important to wash hands before eat- contracted by eating contaminated pork. Show photographs of the pork about proper cooking of pork; practical, ing to prevent infection by parasitic 5. good personal hygiene such as washing P worm adult to your students. the cycle ends here. worms and bacteria. hands, clothing, and bedding 2. The cycle ends here in humans. Any lar- 3. Roundworms can be contracted by eating 6. Make sure students’ tables include P vae in human muscle tissue remains improperly cooked pork and unwashed information from pages 731-733. 732 there. vegetables, walking barefoot, and by lack LS 733 P LS

LS VESTIGATE INVESTIGATE IN E INVESTIGATE Observing Planarian A Eye spot B Head Regeneration P ertain animals have the ability to replace lost body parts Time Allotment C through regeneration. In regeneration, organisms regrow AANALYZENALYZE ANDAND CCONCLUDEONCLUDE 30 minutes the first day, 10 min- parts that were lost. This process occurs in a number of different utes every day for 2 weeks Tail LS phyla throughout the animal kingdom. Examples of animals 1. Planarians belong to the phy- Process Skills that can regenerate include sponges, hydra, mudworms, sea lum Playthelminthes. They are free-living and can be collect data, experiment, think stars, and reptiles. In this activity, you will observe regeneration found in ponds and streams critically, observe and infer, orga- in planarians. Planarians are able to form two new animals 5. Remove the head end and place it 9. Prepare a data table that will living on their own. nize data when one has been cut in half. in a petri dish filled with spring- allow you to record the appear- 2. The head regenerated a new water. Label the dish with the ance of your flatworms every tail, and the tail regenerated a Safety Precautions date, your name, and the word other day for two weeks. Include Make sure students work very “head.” diagrams and the number of days new head. carefully with razor blades. PPREPARATIONREPARATION 6. Add the tail section to a different since starting the experiment in 3. The head section regenerated Remind students to use razor petri dish and label it as in step 5, your data table. a new tail faster. Problem camel hair brush blades carefully to avoid injury. marking this dish “tail.” 10. Observe your animals under a 4. Yes, planarians can regenerate How can you determine if the chilled glass slide Caution them to always cut in a 7. Repeat steps 3-6 with a second binocular microscope and record new body parts. Regeneration flatworm Dugesia is capable of regen- binocular microscope flatworm and add the correct observations and diagrams in occurs through mitosis; no direction away from the body. eration? marking pencil or labels Remind students they are work- pieces to the proper petri dishes. your data table. sexual reproduction or for- single-edged razor blade 8. ing with live animals and to treat Objectives Place the petri dishes in an area mation of gametes was designated by your teacher. them gently. Have students wash In this BioLab, you will: Safety Precautions needed. their hands after working with Observe the flatworm, Dugesia. Always wear goggles in the lab. 5. Answers may vary; there is no planarians. Conduct an experiment to deter- Use extreme caution when cutting need to find a mate, able to ANALYZENALYZE ANDAND CONCLUDEONCLUDE mine if planarians are capable of with a razor blade. Wash your hands A C replace lost body parts, faster Preparation regeneration. both before and after working with 1. Knowledge To what phylum do parts through regeneration? than sexual reproduction, Order planarians so that they planarians. Materials flatworms belong? Are planarians 6. Thinking Critically Would the identical genetic makeup as arrive a day or two before they planarians Skill Handbook free living or parasitic? What is term “clone” be suitable in refer- original animal will be needed. Planarians are petri dish Use the Skill Handbook if you need your evidence? ence to the newly formed planari- 6. Yes, clones may be formed available from biological sup- springwater additional help with this lab. 2. Observing What new part did ans? Explain your answer. asexually by mitosis. Regen- ply houses. Ask for the species, each original head piece regener- eration in planarians is a type Dugesia tigrina. ate? What new part did each of cloning. DO NOT use tap water, dis- PPROCEDUREROCEDURE original tail piece regenerate? Going Further tilled water, or spring water 3. Observing Which section, head Project Design and carry out an experi- purchased from a grocery 1. Obtain a planarian and place it in 3. Place the animal on a chilled glass or tail, regenerated new parts ment that would test this hypothesis: Assessment store. Purchase spring water a petri dish containing a small slide. This will cause it to stretch faster? If regenerating planarians are placed in a Portfolio Have students from a biological supply house amount of springwater. You can out. 4. Interpreting Are planarians able warmer environment, then the time needed write a report on their experi- only. pick up a planarian easily with a 4. Place the slide onto the micro- to regenerate new parts? Would for new parts to form would decrease. mental findings. Be sure to have small camel hair brush. scope stage. While observing the regeneration be by mitosis or To find out more about Alternative Materials 2. Use a binocular microscope to worm through the microscope, meiosis? Explain. regeneration, visit the them include their data table with recorded results. Use the Per- Use a hand lens if binocular observe the planarian. Locate the use a single-edged razor to cut 5. Thinking Critically What Glencoe Science Web Site. www.glencoe.com/sec/science formance Task Assessment List microscopes are not available. animal’s head and tail region and its the animal in half across the mid- might be the advantage for an “eyes.” Use diagram A as a guide. section. Use diagram B as a guide. for Lab Report in PASC, p. 47. A dropper or plastic pipette animal that can grow new body L2 may be substituted for the camel hair brush. 734 SPONGES, CNIDARIANS, FLATWORMS, AND ROUNDWORMS 26.4 ROUNDWORMS 735 Going Further PPROCEDUREROCEDURE Have students redesign the Resource Manager experiment by making differ- Teaching Strategies Data and Observations Internet Address Book ent types of cuts and/or making Section Focus Transparency 66 and Students will observe the flatworms and will Pcuts at different locations on Have students work in groups of 2 or 3. Note Internet addresses Master L1 ELL be able to see those structures shown in the animals’ bodies. Do not feed the planarians while they that you find useful in BioLab and MiniLab Worksheets Figure A. Data table design will vary from are undergoing regeneration. Replace any the space below for quick reference. pp. 118-119 L2 student to student. Encourage students to springwater lost through evaporation. Reinforcement and Study Guide p. 118 P L2 diagram their observations. At the end of LS Store the regenerating pieces in a cool Content Mastery, pp. 129, 132 L1 area (around 20°C) of the classroom and two weeks, students will observe that a new in subdued light. head has formed on the original tail section, 734 and a new tail on the original head section. 735 LS P P P

LS LS P LS

LS Chapter 26 Assessment Chapter 26 Assessment Why are the corals dying? SSUMMARYUMMARY Coral reefs are some of Earth’s most spectacularly beautiful and produc- Main Ideas tive ecosystems. A reef is composed of hundreds of corals that together Section 26.1 Main Ideas Vocabulary Summary statements can be used by external fertilization P create a structure of brightly colored shapes and patterns. In the reef’s A sponge is an aquatic, sessile, asymmetrical, students to review the major con- Sponges filter-feeding invertebrate. (p. 716) cracks and crevices live a dazzling array of fishes and invertebrates. filter feeding (p. 713) cepts of the chapter. Purpose Sponges are made of four types of cells. hermaphrodite (p. 716) Students learn about the impor- Each cell type contributes to the survival internal fertilization Using the Vocabulary oral reefs protect nearby shore areas from Black-band disease is caused by several species of of the organism. (p. 716) tance of coralLS reefs, discover how To reinforce chapter vocabulary, use they can be damaged, and explore Cerosion by breaking up the energy of incom- cyanobacteria that combine to form a band of Most sponges are hermaphroditic with black filaments. This invading community slowly the Content Mastery Booklet and methods for preventing damage. ing waves. But worldwide, coral reefs are increas- free-swimming larvae. ingly being damaged and destroyed. moves across the coral. White-band disease the activities in the Interactive Tutor Background causes the living tissue of a coral to peel away for Biology: The Dynamics of Life on Physical Damage to Coral Reefs from its skeleton; this may be caused by bacteria. Hurricanes Section 26.2 Main Ideas Vocabulary the Glencoe Science Web Site. Corals contain zooxanthellae that cause serious damage to coral reefs, as do large Rapid-wasting disease, possibly caused by a fun- gastrovascular cavity www.glencoe.com/sec/science have chlorophyll and carry out ships that run aground on reefs. Coral reefs lie gus, forms white patches that consume not only All cnidarians are radially symmetrical, aquatic Cnidarians invertebrates that display two basic forms: (p. 719) photosynthesis. During the day, close to the water’s surface, and make attractive the living tissue but also the top layers of the medusa (p. 719) medusa and polyp. most corals withdraw into the anchoring sites for boats. But when an anchor is coral skeleton. nematocyst (p. 719) All Chapter safety of their limestone cups and pulled up, it may rip away a piece of the reef. In Many of the world’s coral reefs are losing Cnidarians feed by stinging or entangling their nerve net (p. 721) their beautiful colors in a process called bleach- prey with cells called nematocysts, usually polyp (p. 719) Assessment let the zooxanthellae make food some parts of the world, explosives are used to mine coral limestone for building materials and ing. The corals become gray or white in color. located at the ends of their tentacles. questions and answers have been for them. At night, corals use fertilizers. Tropical aquarium fishes are some- Some scientists hypothesize that coral bleaching The three primary classes of cnidarians include validated for accuracy and suitabil- their tentacles and nematocysts times collected by poisoning with cyanide, which is the result of a loss of zooxanthellae, the symbi- the hydrozoans, hydras; scyphozoans, jellyfishes; ity by The Princeton Review. to capture planktonic organisms stuns fishes and makes them easier to collect, but otic protists that live in coral and give it much of and anthozoans, corals and anemones. that drift by. also kills corals. Collectors take pieces of coral its color as well as nutrients. for jewelry and souvenirs. Teaching Strategies Different Viewpoints Section 26.3 Main Ideas Vocabulary Damage from Disease Point out to students that, In the 1970s, It is not easy to tell whether microorganisms Flatworms are acoelomates with thin, solid bod- pharynx (p. 727) marine scientists began to realize are causing the diseases or are attacking already Flatworms ies belonging to the phylum Platyhelminthes. proglottid (p. 729) since most coral reefs lie in shal- regeneration (p. 729) that the world’s coral reefs were damaged or ailing corals that have lost their They are grouped into three classes: free-living low waters near the shoreline, scolex (p. 729) being attacked by diseases no natural defenses. Most researchers hypoth- planarians, parasitic flukes, and tapeworms. they are easily affected by coastal one had seen before. esize that coral diseases are on the Planarians have well-developed nervous and activities. The clearing of coastal increase because environmental muscular systems. These systems are reduced in land for development may in- Healthy coral reef (below), changes, such as pollution in coastal parasitic flatworms. Flukes and tapeworms have and diseased reef (right) runoff, higher water levels, or crease erosion. Siltation clouds other structures adapted to their parasitic exis- changes in ocean temperatures, the water and reduces the amount tence. of sunlight available, limiting make corals more vulnerable to photosynthesis by zooxanthellae. opportunistic diseases. Silt can also clog the tiny mouth Section 26.4 Main Ideas Vocabulary opening of the coral polyps, INVESTIGATING THE ISSUE Roundworms are pseudocoelomate, cylindrical none Roundworms worms with lengthwise muscles, relatively com- affecting their ability to feed at Analyzing the Issue What effects night. plex digestive systems, and two body openings. might the death of a coral reef have on nearby ocean and coastal life? Roundworm parasites include parasites Investigating the Issue of plants, fungi, and animals, including humans. Because coral reefs offer an enor- To find out more Ascaris, hookworms, Trichinella, about coral reefs, and pinworms are roundworm parasites mous array of protected living of humans. spaces, the destruction of a reef visit the Glencoe Science Web Site. would remove habitats needed by www.glencoe.com/sec/science many species. Organisms that prey on any of those species CHAPTER 26 ASSESSMENT 737 would lose a food source. Coral reefs also absorb wave energy, so the destruction of a reef could Going Further Internet Address Book Resource Manager leave the shore subject to erosion Intrapersonal A great deal of from wind and wave action. Note Internet addresses VIDEOTAPE research on methods for protecting Chapter Assessment, pp. 151-156 that you find useful in MindJogger Videoquizzes and restoring coral reefs goes on in the MindJogger Videoquizzes the space below for quick reference. Chapter 26: Sponges, Cnidarians, Flatworms Florida Keys. Invite students to use their Computer Test Bank and Roundworms Internet skills to find out about some of BDOL Interactive CD-ROM, Chapter 26 Have students work in groups as they play the problems and solutions scientists are quiz exploring. the videoquiz game to review key chapter concepts. 736 737 Chapter 26 Assessment Chapter 26 Assessment Chapter 26 Assessment Chapter 26 Assessment

8. Two basic body forms are found in ______. NDERSTANDING AIN DEAS NDERSTANDINGNDERSTANDING AINAIN DEASDEAS PPLYINGPPLYING AINAIN DEASDEAS ASSESSINGSSESSING KNOWLEDGENOWLEDGE & SKILLSKILLS TTHINKINGHINKING CCRITICALLYRITICALLY UUNDERSTANDING MMAIN IIDEAS UU MM II a. sponges c. roundworms AA MM II A K & S 1. Which of these is a type of cell found in b. flatworms d. cnidarians 21. In what ways are cnidarians more complex 1. a The diagram shows the life cycle for a beef 25. They are roundworms. Round- sponges? 9. Acoelomate worms called ______have thin, than sponges? tapeworm. worms move with a wriggling 2. c a. epithelial cell c. stinging cell solid bodies. 22. You are examining a wormlike animal found Mature motion because they have no 3. b b. flame cell d. nematocyst a. roundworms c. nematodes Proglottid in the intestine of a sheep. It has a head with tapeworm circular muscles as do earth- 4. c 2. An individual sponge is a hermaphrodite b. flatworms d. hookworms with eggs tiny hooks. What kind of worm is it? worms. 5. c because it ______. 10. Of the following, which is a pseudocoelomate 23. Of what advantage is hermaphroditism to a 26. Human wastes may be disposed 6. d a. reproduces by budding animal? sessile animal? 7. a b. can regenerate lost body parts a. fluke c. tapeworm of in such as way as to prevent 24. Describe the features that would be impor- Eggs in c. can produce both eggs and sperm b. roundworm d. planarian grass fluke eggs from coming in con- 8. d tant for a predator of jellyfishes. Larvae in 9. b d. has both pore cells and stinging cells 11. Examine muscle tact with snails, or humans can avoid contact with water in 10. b 3. Which of the following organisms obtain the diagram. a 11. b food by filter feeding? The cell labeled b TTHINKINGHINKING CCRITICALLYRITICALLY which snails live. 12. hermaphrodite a. jellyfish c. pinworm ______forms c 27. Cnidarians are soft-bodied ani- 25. Observing and Inferring While examining Cow b. sponge d. tapeworm eggs and sperm. d mals that do not preserve well 13. head soil from the bottom of a pond, you notice ingests 4. To what phylum do marine invertebrates eggs as fossils. In corals, their calcium 14. hooks tiny red worms wriggling aimlessly in your with radial symmetry and two body layers 15. fluke petri dish. What kind of worms are they? Interpreting Scientific Illustrations carbonate homes become fos- belong? 16. a 12. A ______is an organism that has both male Use the diagram to answer the following sils, showing where corals once a. Porifera c. Cnidaria 26. Recognizing Cause and Effect At what points 17. cnidarians and female reproductive organs. questions. lived, but the animals them- b. Platyhelminthes d. Cestoda could the life cycle of a blood fluke be inter- 18. Eyespots, planarian 13. Unlike sponges and cnidarians, flatworms rupted so that disease would be prevented? 1. Which part of the life cycle for a beef selves are not fossilized. 5. Both sponges and planarians have ______28. Sponges are filter feeders. They 19. planarian, regenerate have a clearly defined ______. 27. Observing and Inferring Why is the tapeworm is missing? larvae. a. 20. internal fertilization 14. Parasitic worms have mouthparts with phylogeny of cnidarians so little understood? infection of the cow pull water in through pores and a. sessile c. free-swimming b. infection of the grass filter out small particles of food. b. polyp d. budding ______. 28. Comparing and Contrasting Both sponges c. infection of the human host Hydras are cnidarians. They 6. In cnidarians, medusae reproduce sexually to 15. A ______is a parasitic worm that uses a snail and hydras are sessile organisms that cannot d. infection of the tapeworm as an intermediate host and has a larval stage pursue prey. Compare their methods of use nematocysts on long tenta- produce polyps, which in turn reproduce 2. How do the tapeworm eggs get into the cles. When a waving tentacle asexually to form ______. that can bore through the skin of humans. obtaining food. grass? touches a prey organism, the a. buds c. hermaphrodites 16. Examine 29. Concept Mapping Complete the concept a. from rainwater nematocyst discharges, and the b. larvae d. new medusae the diagram. a map by using the following vocabulary terms: b. from feces of infected cattle tentacles bring the captured 7. Sea anemones exhibit only the ______type The structure medusa, nematocyst, polyp. c. from snails b food to the hydra’s mouth for of body form. labeled ______d. from dead cows is used to detect Cnidarians digestion. a. polyp c. bud c d 3. Beef tapeworm larvae get into human b. medusa d. colony food, chemicals, are named for their 29. 1. Nematocysts; 2. Medusa; 3. and movement in hosts when humans ______. a. c. Polyp the environment. 1. eat beef walk barefoot b. eat pork d. go swimming TESTEST–TAKINGAKING TIPIP and have two forms T –T T 17. Hydrozoans and anthozoans are classes of 4. Completing a Diagram By making a 2. 3. Ignore Everyone ______. diagram similar to the tapeworm life cycle on this page, trace the steps of a While you take a test, pay absolutely no attention 18. ______, located on the head of a ______, CD-ROM to anyone else in the room. Don’t worry if your Trichinella infection. 1. c are sensitive to light. For additional review, use the assessment friends finish a test before you do. If someone options for this chapter found on the Biology: The 2. b tries to talk with you during a test, don’t answer. 19. If a(n) ______is cut accidentally, it can Dynamics of Life Interactive CD-ROM and on the 3. a You run the risk of the teacher thinking you were ______lost tissue. Glencoe Science Web Site. cheating—even if you weren’t. 20. 4. Life Cycle of Trichinella In ______, eggs and sperm meet inside an www.glencoe.com/sec/science animal’s body. Feeds contaminated pork scraps to pig

738 CHAPTER 26 ASSESSMENT CHAPTER 26 ASSESSMENT 739

worms. APPLYINGPPLYING MAINAIN IDEASDEAS A M I 23. Animals that are sessile are unable to move Human eats and search for mates. If they are hermaph- improperly Pig eats scraps 21. The two cell layers of cnidarians are orga- cooked pork containing eggs roditic, any individual can be a mate for nized into tissues with specific functions. any other individual of the same species. They have simple nervous systems, cells that 24. Predators of jellyfishes must be immune to can contract like muscles, nematocysts that the toxins in jellyfishes, or have a protective are used to capture prey, and a gastrovas- covering such as mucus on the body that cular cavity in which digestion occurs. Worm develops in could absorb the nematocysts’ toxins. pig muscle tissue 22. It is a parasitic flatworm. A head with hooks is characteristic of parasitic flat- 738 739