Focus on California Life Science 7th Grade Unit 3 - Chapter 11 Structure and Function and Invertebrates

) Chapter Structure and Function of Invertebrates Standards Preview A typical cell of any ism contains genetic instructions that specify its traits . Those traits may be modified by tal influences . As a basis for understanding this concept a Students know the differences between the life cycles and reproduction methods of sexual and asexual organisms . Biological evolution accounts for the diversity of species oped through gradual processes over many generations . As a basis for understanding this concept Students know how to a simple branching dia gram to classify living groups of organisms by shared derived characteristics and how to expand the diagram to include fossil organisms . The anatomy and physiology of plants and animals illustrate the complementary nature of ture and function . As a basis for understanding this concept a . Students know plants and mals have levels of structure and function , including cells , tissues , organs . organ systems , and the whole organism . Students know organ systems function because of the of individual organs , and . The failure of any part can affect the entire system This Asian weevil uses its front I legs to court females .

Mollusks , Arthropods , and Focus on the BIG Idea What major functions do animals bodies perform ?

Check What You Know On a walk through the park , you stop to look closely at the leaves of a plant . You see an insect laying eggs . The eggs are the result of sexual reproduction . The cells in each insect egg contain many genes . Where do these genes come from ?

Explain your answer . Chapter 11 405 The images shown here represent some of the key terms in this chapter . You can use this vocabulary skill to help you understand , the meaning of some key terms in this chapter . Use Clues to Determine Meaning In this textbook , important new words , or key terms , first appear in dark type with a yellow highlight . The dark type and yellow highlight are clues that the meanings , or definitions , of these words are given in the text . Sometimes the meaning is in the same sentence as the key term . Other times , you need to look at several sentences to understand the key term meaning completely . Look The animals called have two different at the example below . what a El ) glans . One form looks something like a vase . is The body plan is called a polyp . A mouth opens at the top and its tentacles spread out from around the mouth . Additional information about a polyp Apply . In your own words , what is the meaning of polyp ?

what sentence contains the definition of polyp ?

What help you understand the meaning of polyp ?

Chapter Vocabulary Section ( page 410 ) anatomy radial physiology bilateral vertebrate , symmetry invertebrate I I phylum Section ( page ) larva polyp cnidarian medusa Section ( page 424 ) brain gill ) parasite gastropod . host radula I . anus bivalve mollusk cephalopod open circulatory system closed circulatory system Section ( page 434 ) arthropod insect ' exoskeleton thorax molting pupa antenna nymph crustacean arachnid abdomen metamorphosis Section ( page 443 ) echinoderm endoskeleton water vascular system tube feet Online Visit . om Web Code . i Build Science Vocabulary Chapter 11 401

, Read ei Reading Skill Take Notes When you take notes , you write the important ideas from the textbook in shortened form . See the sample notes below , which are notes on the beginning of Section in this chapter . Use a red or blue heading as the title of your notes . In the left column , write questions about the text that follows the heading . The questions should ask for important information . Write the answers in the right column . Write a summary statement that expresses the main idea of the information under the heading . Questions Notes of Animals What do and structure mean ?

in organisms How are animal cells Into tissues , organs , organ systems organized ?

What are tissues . cells doing functions organs . and organ doing complex function systems ?

Organ of structures that perform broadest function Summary Statement In most animals . calls are Into tissues , organs . and organ systems . Apply It ! In your notebook , complete the notes for Section . Then take notes on Section .

, Standards Investigation Going Through Changes nu Most of the animals you will read about in this chapter change form during their development . In this investigation . you will observe firsthand how mealworms change as they develop . Your Goal To observe development and how different conditions affect that development To complete this investigation , you must compare development under two different conditions record your observations daily for several weeks describe the process of development that you observe draw about the effects of those conditions on development follow the safety guidelines in Appendix A Plan It ! Find two containers , such as clean margarine tubs with lids , in which to keep the mealworms . Get some food , such as cornflakes , and a plastic spoon to transfer the food and count the mealworms . Choose two conditions , such as two different temperatures or food sources . and plan how to test the two conditions . Once you begin , record your daily observations in a data table , and sketch each stage of development . Chapter 11 409

0000 Students know plants and animals have levels of organization for structure and function , ing cells , tissues , organs . organ systems , and the whole organism . How are animal bodies typically organized ?

What are four major functions of animals ?

What is symmetry ?

How are animals classified ?

Key Terms anatomy physiology bilateral symmetry ' radial symmetry vertebrate invertebrate phylum A feeding ( inset ) A and many at rest ( right ) 410 What Is an Animal ?

73 ! Standards Is It an Animal ?

Carefully examine each of the organisms that your teacher gives you . Decide which ones are animals . For each organism , write down the reasons for your decision . Wash your hands after handling each of the organisms . Think Over Forming Operational Definitions Use your notes about each organism to write a definition of animal . Your parents may have told you not to eat with your , but they probably never worried that you eat with your feet ! But animals called barnacles do just that . A barnacle begins life as a speck that swims in the ocean . After a while , it settles its head down on a hard face . Then it builds a hard cone around its body . To feed , the its feathery feet in and out of the cone , as shown below . The feet trap tiny organisms that in the water . A barnacle may look like a rock , but it is actually an animal . Animals are organisms that typically obtain food by eating other organisms .

Structure of Animals An organisms structure is called its anatomy . In animals , as in all living things , the basic unit of anatomy is the cell . The cell is also the basic unit that carries out life processes , or functions . Physiology is the study of functions in organisms . The cells of most animals are organized into higher levels of structure , including tissues , organs , and organ systems . A group of cells that perform a function is called a tissue . One type of tissue is bone tissue , a hard tissue that gives bones their strength . Tissues may combine to form an organ , which is a group of several different tissues . For example , a frog thigh bone is posed of bone tissue , nerve tissue , and blood . An organ performs a more complex function than each tissue could perform alone . Groups of structures that perform the broadest functions of an animal are called organ systems . One example is the etal system of a frog shown in Figure The skeletal system and I the body other organ systems together make up a whole ' it . am wor organism . In this case , the organism 18 a frog . systems to carry out all of the What is an organ ?

frog life functions . FIGURE Levels of Organization A frog skeletal system has different levels of organization . interpreting Diagrams List the levels of organization in order from smallest to largest . organ system Together . all of the bones form the skeletal system . Organ A group of different kinds . of tissues make up an organ such as the thigh bone . I Many bone cells make up bone tissue . I Cells Cells are the basic unit of animal structure . 411

FIGURE Obtaining Food This tarantula uses its fangs to kill a grasshopper . INl ' CED For Links on the animal kingdom Visit Web Code FIGURE Keeping Cool This dog is keeping cool by getting wet and panting . 412 Functions of Animals All animals carry out the same basic physiological processes . Some major functions of animals are obtaining food and oxygen , keeping internal conditions stable , moving , and reproducing . Adaptations are structures or behaviors that allow animals to perform these functions . In animals , anatomy is closely related to physiology . In other words , the structures of cells , tissues , organs , and organ systems are closely related to their functions . Think of the frogs skeletal system . Bones have a strong , tough structure . This structure functions to support the frogs body . Obtaining Food and Oxygen An animal obtains food by eating other organisms . Animals may feed on plants , other animals , or a combination of plants and animals . They have adaptations that allow them to eat particular foods . For ple , the tarantula in Figure has fangs . Fangs are structures it uses to pierce other animals and suck up their juices . Food provides animals with raw materials for growth and with energy for their bodies activities , such as breathing and moving . Most animals take food into a cavity inside their ies . Inside this cavity the food is digested . or broken down into substances that the animals body can absorb and use . To release energy from food , the body cells need oxygen . Some animals , like birds , get oxygen from air . Others , like . get oxygen from water . Keeping Conditions Stable Animals must tain a stable environment within their bodies . If this balance is lost , the animal can not survive for long . For example , cells that get too hot start to die . Therefore , animals in hot environments have adaptations to keep their bodies cool . During hot days , earthworms stay in moist soil , lizards crawl to shady places , and dogs pant .

Movement All animals move in some way at some point in their lives . Most animals move freely from place to place throughout their example , by swimming , walking , or hopping . Other animals , such as oysters and , ii an anima a new move from place to place only during the earliest stage of their and way of moving . lives . After they a good place to attach , these animals stay Your design your me animal obtain food or get Many animals have muscles and bones , which are out of danger . that enable them to move . When muscles contract , or shorten , an Make and a drawing animals body moves . Many animals have internal skeletons . In that show how the animal these animals . muscles are attached to bones by structures called would move . tendons . When the muscles contract , they pull on the bones . This . Using clay , aluminum cans , pulling makes the bones move . UC Paper . Pipe cleaners , and whatever Reproduction Like all organisms , animals must reproduce . Most animals reproduce sexually . Sexual reproduction is the a a . dimensional model of process by which a new organism develops from the of . your animal . two sex male sperm cell and a female egg cell . The . Ito of an egg cell and a sperm cell is called fertilization . Sperm your those of other classmates . and egg cells carry information about the characteristics of the what are some ?

parents that produced them , such as size and color . New What are some differences ?

resulting from sexual reproduction have a combination of Making Models what characteristics from both parents . features YOUT design help Some animals can reproduce asexually as well as sexually . a ' a ' escape danger ?

Asexual reproduction is the process by which a single ism produces a new organism identical to itself . For example , animals called sea anemones sometimes split down the middle , producing two identical organisms . 39 , What is asexual reproduction ?

FIGURE Owl Family Baby owls are produced by sexual reproduction . Classifying which kind of reproduction involves fertilization ?

Chapter 11 413 Bilateral Symmetry ' FIGURE Types of Symmetry Most animals have either bilateral or radial symmetry . Most sponges , however , have no symmetry . 414 No Symmetry Radial Symmetry Symmetry The functions an animal carries out are closely related to its body structure . One part of body structure is the presence or absence of symmetry . Symmetry is a balanced ment of body parts that is characteristic of many animals . Animals have different types of symmetry . An animal has bilateral symmetry if there is just one line that divides it into halves that are mirror images . Fishes , such as the one in Figure , have bilateral symmetry . In contrast , an animal with radial symmetry , such as a sea star , has many lines of try that divide it into two identical halves . A few animals , such as sponges , have no symmetry . Animals With Radial Symmetry The external body parts of animals with radial symmetry are equally spaced around a central point , like spokes on a wheel . Animals with radial , such as sea urchins and , do not have distinct front or back ends . All animals with radial symmetry live in the water . Most of them do not move very fast . Animals with Bilateral Symmetry In general , animals with bilateral symmetry , such as insects and frogs , are larger and more complex than those with radial symmetry . They have a front end that typically goes first as the animal moves along . These animals move more quickly and efficiently than most animals with radial symmetry . In addition , most animals with bilateral symmetry have sense organs in their front ends that pick up information about what is in front of them . A , for example , has eyes on its head . Routing Where are the sense organs of an animal with ) bilateral symmetry typically found ?

to classification of Animals Biologists have more than million species , or tinct types , of animals . Classifying animals helps biologists make sense of this diversity . In Figure , you can see some of the largest groups of animals . The pattern of the diagram in Figure shows how some of the major groups of animals may be related . For example , by looking at their positions on the tree , you can see that segmented worms are probably more closely related to arthropods than to sponges . Mammals I Centipedes Insects ?

Crustaceans Mollusks Flatworms Sponges noun Major Animal Groups This diagram shows the major animal groups . Interpreting Diagrams Are more closely related to or mollusks ?

chapter 11 415 House Discovering New Species This biologist is surveying the leaves of rain forest plants , looking for new insect species . Section Target Reading Take Notes Use the notes you wrote about this section to help answer the questions below . Reviewing Key Concepts a . Defining What is the basic unit of structure and function in an animal ?

is . Sequencing Arrange in order from simplest to most complex structure tissue , organ system , whole organism . cell , organ . a . Reviewing What are five major functions of animals ?

Identifying identify the two ways in which animals reproduce . Assessment Animals are according to how they to other animals . These relationships are determined by an animal body structure . the way the animal develops , and its DNA . DNA is a chemical in cells that controls an organism inherited characteristics . All vertebrates . or animals with a backbone , are in only one phylum . All the other animal phyla contain invertebrates . or animals without backbones . Of all the types of animals , about 97 percent are invertebrates ! Biologists such as the one in Figure continue to new animal species . New species are based on the kinds of evidence above . Biologists have animals into about 35 major groups . each of which is called a phylum ( lum ) plural phyla ) Biologists think animal life has evolved . or changed over time . Biologists do not know the exact way in which animal evolution took place . Instead , they can only make inferences on the basis of the best evidence available . Biologists hypothesize that all animals arose from celled ancestors . Writing , Reading . Defining What ?

Comparing and Contrasting and bilateral different ?

Applying Concepts An animal runs rapidly forward to catch its prey . Which type of symmetry does the animal probably have ?

Explain . a . Defining What is a vertebrate ?

Classifying How do biologists classify animals ?

Interpreting Diagrams According to Figure , are reptiles more closely related to mammals or to ?

Explain your answer . Relating Cause and Effect Which type of reproduction produces offspring with a combination of characteristics of two parents ?

How does it produce the combination ?

416 Writing in Science Section A ( Standards Focus Students know the between the life cycles and reproduction methods of sexual and asexual organisms . Students know plants and animals have levels of organization for structure and function , ing cells , tissues , organs , organ , and the whole organism . What are the main characteristics of sponges ?

What are the main characteristics of Key Terms larva cnidarian ' polyp medusa Sponges and ards How Do Natural and Synthetic Sponges Compare ?

Examine a natural sponge , and then use a hand lens or a microscope to take a closer look . Look carefully at the holes in the sponge . Draw what you see through the lens . gig Cut out a small piece of sponge and examine it with a hand lens . Draw what you see . Repeat Steps and with a synthetic kitchen sponge . think It Over Observing what are three ways a natural and a synthetic sponge are similar ?

are three ways they are different ?

Eagerly but carefully , you and the others in your group put on scuba gear as you prepare to dive into the ocean . Over the side of the boat you go . As you descend through the water , you see many kinds of . When you get to the bottom , you notice other organisms , too . Some are as strange as creatures from a science movie . A few of these unusual organisms may be invertebrate animals called sponges . Sponges do look or act like most animals you know . in fact , they are so different that for a long time , people thought that sponges were plants . Like plants , adult sponges stay in one place . But unlike most plants , sponges take food into their bodies . Sponges Sponges live all over the in oceans , but also in freshwater rivers and lakes . Adult sponges are attached to hard surfaces underwater . Water currents carry food and oxygen to them and take away their waste products . Water currents also play a role in their reproduction and help transport their young to new places to live . Diver investigating a barrel sponge 411

food . remove wastes . and form . sperm or egg cells . Body Structure Sponges are invertebrates that usually have no body symmetry and never have tissues or organs . Although sponges do not have tissues , they have cells that are specialized for different functions . For example , collar cells move water through a sponge and trap food . Go Reproduction Sponges reproduce sexually , but they do not ac ( ark have separate sexes . A sponge produces both sperm cells and egg cells . Sperm cells are released into the water . They enter We ?

a another sponge and fertilize its eggs . After fertilization , a larva develops . A larva ( plural larvae ) is an immature form of an animal that looks very from an adult . Sponges also reproduce asexually . ture of a Sponge ! iE ' What is the function of collar cells ?

Structures surrounding the central cavity of a sponge are adapted for different functions . Interpreting Diagrams Which kind of cell in the sponge digests and distributes food ?

water moves into the central cavity through small pores all Cell the , I . The collar cells have structures that heat back and forth . moving water through the sponge and trapping food . Spire Thin spikes form a rigid frame that helps support and protect the sponge body . Cell Among the spikes are cells that digest and distribute A

Some other animals you might notice on an underwater dive are , sea anemones , and the tiny corals that build coral reefs . These animals are ( ny ee ) invertebrates that have stinging cells and take food into a body cavity . use stinging cells to capture food and defend themselves . Body Structure have two different body plans . One form looks something like a vase and the other form looks like an bowl . Both body plans have radial , a central hollow cavity , and tentacles with stinging cells . The body plan is called a polyp ( ip ) The sea anemone you see in is a polyp . A polyp mouth opens at the top and its tentacles spread out from around the mouth . Most polyps are adapted for a life attached to an underwater surface . The body plan is called a ( muh suh ) The you see in Figure is a medusa . A medusa , unlike a polyp , is adapted for a swimming life . have mouths that open downward and tentacles that trail down . Some go through both a polyp stage and a medusa stage during their lives . Others are either polyps or for their entire lives . Cnidarian Body Plans have two basic body forms , the polyp and the medusa . Comparing and Contrasting Contrast the location medusa . Hydra Doing ?

Put a drop of water containing in a small unbreakable bowl or petri dish . Allow it to sit or about 15 minutes . Use a hand lens to examine the as they swim . Then gently touch the tentacles of a hydra with the end of a toothpick . Watch what happens . Return the to your teacher . Wash your hands . Classifying Isa hydra a polyp or a Describe its method of movement .

FIGURE 10 Cnidarian Attack ! A stinging cell fires when its trigger brushes against prey , such as a fish . Applying Concepts What is the function of stinging cells ?

4200 Trigger Stinging Call at Rest Spines Stinging Cell After Firing Obtaining Food use stinging cells to catch the animals they eat , which are called prey . You can see a stinging cell in Figure 10 . The cell contains a threadlike structure , which has many sharp spines . When the stinging cell touches prey , this threadlike structure explodes out of the cell and into the prey . Some stinging cells also release venom into the prey . When the prey becomes helpless , the cnidarian uses its tentacles to pull the prey into its mouth . From there , the prey passes into a hollow central body cavity , where it is digested . Undigested food is expelled through the mouth . Movement Unlike adult sponges , many can move to escape danger and to obtain food . Some have tissues that allow them to move in different ways . swim through the water , and turn slow somersaults . A cnidarian movements are directed by nerve cells that are spread out like a basketball net . Reproduction reproduce both asexually and sexually . For polyps such as , corals , and sea anemones , budding is the most common form of asexual reproduction . In budding , small new animals grow from the side of an adult mal . Asexual reproduction allows the numbers of polyps to increase rapidly in a short time . Sexual reproduction in occurs in a variety of ways . Some species of have both sexes within one individual . In others , the sexes are separate individuals . Many have life cycles , or a sequence of different stages of development . In Figure , you can see the life cycle of a moon jelly , which involves both asexual and sexual reproduction . Reading What is an example of asexual reproduction seen ea ) in ?

mun 11 Cycle of a The life cycle of a Adult reproduce sexually moon Jelly has both a by releasing egg and sperm cells . polyp and a medusa stage , both ' 32 ! SPENT ?

Es ) A sperm cell fertilizes an egg cell . A swimming larva develops . The larva attaches to a hard surface and develops into a polyp . Section Assessment Target Reading Skill Take Notes Use the notes you . wrote about this section to help answer the questions below . i Reviewing Key Concepts a . Describing What are the characteristics of a sponge ?

Explaining How does a sponge reproduce sexually ?

Identifying What is one type of cell that all have ?

Sequencing What steps are involved in how a cnidarian obtains food ?

How might a cnidarian protect itself ?

Chapter 11 421 Science and Coral Reefs in Danger Coral reefs are built by coral polyps , which are tiny , delicate . Recreational divers can damage coral reefs . This damage changes the corals environment , and corals mav not have adaptations that enable them to survive the damage . The issues What the Harm in Diving ?

More than million divers live in the United States , With so many it is hard to guarantee that no harm will occur to coral reefs . Divers can cause by standing on or even touching these fragile reefs . Harm to the reefs is even more likely to occur when divers collect coral for their own or to sell for . You can see colored coral from the sea in and in decorations . Should Reefs Be Further Protected ?

The United States government has passed laws it illegal , under most , to remove coral from the sea . Because a few divers break these laws , some people want to ban altogether . However , many divers say its to ban diving just because ofa few lawbreakers . divers consider coral reefs the most exciting and beautiful places in the ocean to explore . As divers and other people visit and learn more about these delicate coral reefs , they increase others awareness of them . Public awareness may be the best way to ensure that these rich are protected . More Than a Diving Issue Coral reefs are major tourist attractions that bring money and jobs to people in local . were . local businesses would stiffer . Also . although divers can harm coral reefs . other activities that result in ocean pollution . oil spills , and illegal can also cause harm . In addition , natural events , such as tropical , changes in sea level , and in sea . can also damage the fragile reefs . 422

A . What Would You Do ?

A . Identify the Problem In your own words . the controversy ( near coral reefs . Analyze the Options List ' on side of the issue . Note the pros and cons . low well would each protect the reefs ?

Who might be ur ?

Reefs house and protect many species of sea animals , including sponges , a shrimp , sea turtles , and fishes . Write a stating your diving should lie near reefs . State and reasons i . can For Mote on coral reefs Visit Web Code ! Standards ( Section Worms and Mollusks What Does a Flatworm Look Like ?

Your teacher will give you a planarian , a kind of flatworm . Pick the worm up with the tip of a small paintbrush . Place it carefully in a container . Use a dropper to cover the planarian with spring water . Observe the planarian with a hand lens for a few minutes . Describe how the planarian moves . Draw a picture of the planarian . Return the planarian to your teacher , Students know the between the life cycles and reproduction methods of sexual and asexual organisms . Students know plants and animals have levels of organization for structure and function , ing cells , tissues , organs , organ , and the whole organism . What are the main characteristics and wash your hand , of worms ?

What are the main characteristics over I . of am of worms , How does a What are the main characteristics er a sponge of mollusks ?

What are the main groups of Worms in the soil and snails in an aquarium do seem to have much in common . But worms and snails are both invertebrates with soft bodies . In fact , some mollusks even look like worms . rain parasite Characteristics of Worms ' am , You might think that all worms are small , slimy , and wriggly . closed circulatory system . But many worms do not that description . Some worms are . open , system almost three meters long and are as thick as your arm . All . worms are invertebrates have long , narrow bodies gastropod without legs . Biologists classify worms into three major ' and segmented worms . worms belong to the phylum ( plat ee HE . eez ) belong to the phylum . Segmented worms belong to the phylum . Flam ! 12 Giant Earthworm A giant earthworm can grow to be more than meter long . It is one of earthworm species found in Australia . 4249

FIGURE 13 Three Phyla of Worms The three major phyla of worms are flatworms , and segmented worms . Observing How are the body shapes of these three types of worms similar ?

Roundworm A Long , round body Flatworm A Long , flat body Body Structure Unlike sponges or , worms have bilateral symmetry . Therefore , they have head and tail ends . In addition , they all have tissues , organs , and body systems . Nervous System Worms are the simplest organisms with a brain , which is a knot of nerve tissue located in made up of the head end . The brain controls most of the animal segments body functions . Sense organs pick up information from the environment . The brain interprets that information and directs the animal response . For example , suppose an earthworm on the surface of the ground senses the vibrations of a footstep . The worm will respond by returning to its underground burrow . A worm can detect objects , food , mates , and predators quickly . It can respond quickly , too . Reproduction Both sexual and asexual tion are found in the worm phyla . Some worms , such as the , reproduce asexually by dividing into two separate organisms . The two new organisms are genetically identical . Most worm species can reproduce sexually . In many species , there are separate males and females , as in humans . In other species , each animal has both male and female sex organs . An animal with both male and female sex organs is called a hermaphrodite ( hur ruh ) Usually , two individual mate and exchange sperm . It is rare for a hermaphrodite to fertilize its own eggs . When fertilization happens , it is still a form of sexual reproduction , even though there is only one parent . What type of symmetry do worms have ?

0425 noun 14 Planarian are flatworms that live in ponds , streams , and oceans . Comparing and Contrasting How does a organism differ from a parasite ?

Go Fan More on worms Visit Web Code 4266 Flatworms As you expect from their name , flatworms are . They include such organisms as tapeworms , and . Although tapeworms can grow to be 10 to 12 meters long , some other are almost too small to be seen . Flatworms are and as soft as jelly . Many are parasites . A parasite is an organism that lives inside or on another organism . The parasite takes its food from its host , the organism in or on which it lives . sites may rob their hosts of food and make them weak . They may injure the host tissues or organs , but they rarely kill their host . All tapeworms and flukes are parasites . In contrast , some flatworms are . organism does not live in or on other organisms . may glide over the rocks in ponds , slide over damp soil , or swim slowly through the ocean like ruffled , brightly patterned leaves . are flatworms . are feed on dead or decaying material . But they are also predators . A predator is an animal that captures another animal for food . will attack any animal smaller than they are . A planarian feeds like a vacuum cleaner . The planarian glides onto its food and inserts a feeding tube into it . Digestive juices out of the planarian and into the food . These juices begin to break down the food while it is still outside the worms body . Then the planarian sucks up the partly digested bits . Digestion is completed within a cavity inside the planarian . Undigested food exits through the feeding tube .

If you look at the head of the planarian shown in Figure 14 , you can see two dots . These dots are called . The spots can detect light but can not see a detailed image as human eyes can . A planarian head also has cells that pick up odors . rely mainly on smell , not light , to locate food . Tapeworms Tapeworms are one kind of parasitic flatworm . The structure of a tapeworm body is adapted to the function of absorbing food from the host digestive system . Some kinds of tapeworms can live in human hosts . Many tapeworms live in more than one host during their lifetime . Figure 15 shows the life cycle of the dog tapeworm . This tapeworm has two ent dog and a rabbit . How does a scavenger obtain food ?

FIGURE 15 Life Cycle of a Dog Tapeworm The tapeworm is a parasite that lives in more than one host during its life cycle . Tapeworm larvae can infect a dog host The immature when the dog eats an tapeworm uses infected wild animal , hooks and Suckers such as a rabbit . on its head to dig into the lining of the dog digestive system . The fertilized eggs get on grass and other plants eaten by rabbits . After rabbits eat the eggs , the larvae hatch The tapeworm grows as it absorbs food from the dog intestine . Then the tapeworm produces eggs and sperm . Fertilized eggs leave the digestive system along with the dog wastes . 427

The next time you walk along a beach , consider that about a million live in each square meter of damp sand . can live in nearly any moist including forest soils , Antarctic sands , and pools of water . Most are tiny and to see , but they may be the most abundant animals on Earth . Some species are and some are parasites . Unlike , have cylindrical bodies . They look like tiny strands of cooked spaghetti that are pointed at each end . Unlike or , have a digestive system that is like a tube , open at both ends . Food travels in one direction through the roundworm tive system . Food enters at the animals mouth , and wastes exit through an opening , called the aims , at the far end of the tube . The structure of a digestive system is efficient . It is 16 something like an assembly line , with a different part of the digestive function happening at each place along the line . The Digestion happens in orderly stages . First , food is broken down roundworm has been stained . Th th undera . ent oo . isa sor into microscope , animals body . Finally . wastes are eliminated . This type of digestive system enables the body to absorb a large amount of the needed substances in foods . Reading what are the openings at opposite ends of Checkpoint ) a digestive tube called ?

Math Algebra and Functions . i . Numbers Distribution of Biologists counted all the living in a plot of soil . Then they calculated the percentages that live in different centimeter depths of soil . Their results are graphed to the right . Data . Reading Graphs Where in the soil was the largest percentage of found ?

Calculating What is the total percentage of found in the first depth of soil ?

Percentage of Found . Drawing What is the relationship between the depth of the soil and the abundance of in the soil ?

Depth of Soil ( 4230 Segmented Worms If you have ever dug in a garden , you have probably seen earthworms wriggling through the moist soil . Earthworms are segmented worms . So are leeches and some worms . Body Structure When you look at an earthworm . you see a body made up of a series of rings separated by grooves , something like a vacuum cleaner hose . and other segmented worms have bodies made up of many linked sections called segments . On the outside , the ments look nearly identical , as you can see in Figure 17 . On the inside , some organs are repeated in most segments . For example , each segment has tubes that remove wastes . Other organs , however , such as the earthworm reproductive organs , are found only in certain segments . Segmented worms have organ systems . For example , segmented worms have a nervous system that includes a brain and a nerve cord that runs the length of the worms body . Like , segmented worms have a way digestive system with two openings . Circulatory System Segmented worms have a closed system . In a closed circulatory system , blood moves only within a connected network of tubes called blood vessels . In contrast , some animals , such as snails and lobsters . have an open circulatory system in which blood leaves the blood vessels and sloshes around inside the body . In both open and closed circulatory systems . blood carries out the physiological process of bringing oxygen and food to cells . But a closed circulatory system can move blood around an animal body much more quickly than an open circulatory system can . organs Blood vessels FIGURE 17 Structure of an Earthworm An earthworms body is divided into more than 100 segments . Some organs are repeated in most of those segments . Other organs exist in only a few segments . Interpreting Diagrams Name an example of a body system that runs through all of the worm segments . Reproductive organs Digestive tract Chapter 11 429

FIGURE 18 Comparing Mollusks Although they do look much alike at first , a snail . a clam , and a squid have the same basic body structures . I Mantle I Foot I Digestive tract 4300 Characteristics of Mollusks Clams , oysters , and scallops are all mollusks ( phylum ) Snails and squids are . too . Mollusks are invertebrates with soft , unsegmented bodies that are often protected by a hard outer shell . All mollusks have the same covered by a shell , a mollusk has a thin layer of tissue called a mantle that covers its internal organs , and an organ called a foot . In many mollusks , the mantle produces the hard shell . Depending on the type of mollusk , the foot has different , digging , or ing prey . Body Like segmented worms , have bilateral symmetry and a digestive system with two openings . However , unlike worms , the body parts of mollusks are not usually repeated . Instead , the internal organs are located together in one area , as shown in Figure 18 . Circulatory System Most groups of mollusks havean blood is not always inside blood vessels . The heart pumps blood into a short vessel that opens into the body spaces containing the internal organs . The blood sloshes over the organs and returns eventually to the heart . Obtaining Oxygen Most mollusks that live in water have gills , organs that remove oxygen from the water . The gills have tiny , hairlike structures called cilia and a rich supply of blood vessels . The cilia move back and forth , making water over the gills . The gills remove the oxygen from the water and the gen moves into the blood . At the same time , bon dioxide , a waste gas , moves out of the blood and into the water . leading ' I organs of a mollusk . obtain oxygen from water ?

Diversity of Mollusks Biologists classify mollusks into groups based on their cal characteristics . These characteristics include the presence of a shell , the type of foot , and the type of nervous system . three major groups of mollusks are . bivalves , and cephalopods . The include snails and slugs . have a single shell or no shell at all . Some are herbivores , animals that eat only plants . Some are gers that eat decaying material . Still others are carnivores , animals that eat only other animals . No matter what food they eat , use an organ called a radula to obtain food . A radula ( RAl oo luh ) is a organ with tiny teeth . A gastropod usually moves by creeping along on a broad foot . The foot may ooze a carpet of slippery mucus . The mucus makes it easier for a gastropod to move . Bivalves Bivalves include oysters , clams , scallops , and . are mollusks that have two shells held together by hinges and strong muscles . Unlike , bivalves do not have . Instead , most bivalves are feeders that strain tiny organisms from water . Most bivalves are herbivores , animals that eat plants . Most adult bivalves don move quickly . They stay in one place or use their foot to move very slowly . How do bivalves obtain food ?

Classifying While wading in a stream , you step on a small animal with a hard covering . As you examine the animal , you discover that it has a soft body inside its shell . It may be a mollusk . What characteristics would you look for to classify the animal into a group of mollusks ?

19 The Radula of a Snail such as this land snail have an organ called a radula , which tears and scrapes up food . Applying Concepts How is the structure of a radula related to its function ?

FIGURE 20 A Cephalopod An octopus is a cephalopod . In cephalopods . the foot forms tentacles . Cephalopods Octopuses , squids . and are cephalopods . A ( SEF uh luh ) is an Ill Hill mollusk whose foot forms tentacles around its , A , mouth . Some cephalopods lack shells . Cephalopods are the and only mollusks with a closed circulatory system . Cephalopods are carnivores . They use their muscular to capture prey . Large eyes and a complex nervous system also help them capture prey . have large brains and can remember things they have learned . Assessment Vocabulary Skill Use Clues to Determine a . Listing List the characteristics of a mollusk . the . Explaining How is a mollusk mantle under . What does parasite mean ?

to its Shel ?

What clues help you understand the meaning ?

identifying What are three groups of Reviewing Key Concepts ?

Classifying What are the characteristics of . a . Reviewing What are the general th th . rec groups of mollusks ?

of worms ?

arm , CO th Identifying In what two ways do worms an on reproduce ?

functions of the foot in the three groups . Explaining hermaphrodite worms , how does usually take place ?

a . Listing List the main phyla of worms . Comparing and Contrasting Contrast the ways the major worm phyla digest food . Edible Mollusks Visit a supermarket with a i . Applying Concepts A worm takes in food family member and identify any mollusks that at its front end and expels undigested are being sold as food . Pans Of wastes from the other end . Can the worm the mollusks are Used be a ?

Explain . 432 a Earthworm Responses . Problem Do earthworms prefer dry or moist conditions ?

Do they prefer light or dark conditions ?

Skills Focus observing . interpreting data Materials plastic dropper water cardboard clock or watch paper towels flashlight earthworms storage container tray Procedure . environment do you think or moist ?

Record your hypothesis in your notebook . Use the dropper to sprinkle water on the worms . Keep the worms moist at all times . Fold a dry paper towel and place it on the bottom of one side of your tray . Fold a moistened paper towel and place it on the side . your hands . Then place the worms in the center of the tray . Make sure that half of each earthworm body rests on the moist paper towel and half rests on the dry towel . Handle the worms gently . Coverthe tray with the piece of cardboard . After five minutes , remove the cardboard and moist or dry surface . Record your observations . the earthworms to their storage . Moisten the earthworms with water . which do you think earthworms strong light or darkness ?

Record your hypothesis in your notebook . Dry paper towel Wet paper towel . Cover the whole surface of the tray with a moistened paper towel . 10 . Place the earthworms in the center of the tray . Cover half of the tray with cardboard . Shine a flashlight onto the other half . After five minutes , note the locations of the worms . Record your observations . 12 . Repeat Steps 10 and 11 . 13 . Moisten the earthworms and put them in the location designated by your teacher . Wash your hands after handling the . Analyze and conclude . Observing How did the earthworms respond to moisture ?

How did they respond to darkness ?

Interpreting Data What organ in the worms bodies directed their responses ?

If that organ were damaged , how might the earthworm response have been different ?

Communicating Write a description of how an earthworm moves . In your description , identify the type of tissue that enables an animal to move . Design an Experiment Do earthworms prefer a smooth or rough surface ?

Write your hypothesis . Then design an experiment to answer the question . Obtain your teacher mission before carrying out your investigation . Chapter 11 433 ' Standards Focus Students know the between the life cycles and reproduction methods of sexual and asexual organisms . Students know organ systems function because of the contributions of individual organs , tissues , and cells . The failure of any part can affect the entire system . What are the general characteristics of arthropods ?

What are the distinguishing structures of crustaceans , arachnids , centipedes and millipedes , and insects ?

Key Terms arthropod exoskeleton molting antenna crustacean I metamorphosis arachnid abdomen I insect thorax complete metamorphosis ' gradual metamorphosis nymph FIGURE 21 A Spider at Work This spider wraps its prey , a grasshopper , in silk . Both animals are arthropods . 4340 Arthropods ?

Will It Bend and Move ?

Have a partner roll a piece of cardboard around your arm to form a tube that covers your elbow . Your partner should put three pieces of tape around the tube to hold it at each end and one in the middle . With the tube in place , try to write your name on a piece of paper . Then try to scratch your head . Keep the tube on your arm for 10 minutes . Observe how the tube affects your ability to do things . Think it Over Inferring Insects and many other animals have rigid skeletons on the outside of their bodies . Why do their skeletons need joints ?

Standards At dusk near the edge of a meadow . a grasshopper leaps through the grass . Nearby , a hungry spider waits in its web . The grass hopper leaps into the web . caught ! As the grasshopper to free itself , the spider rushes toward it . Quickly . the spider wraps the grasshopper in silk . The grasshopper can not escape . Soon it will become a tasty meal for the spider . The Spider and grasshopper are both arthropods , or members of the arthropod phylum ( phylum ) Animals such as crabs , lobsters , and scorpions are also arthropods .

! I in am at FIGURE 22 Arthropod Characteristics This Sally crab shows the tough exoskeleton and the jointed appendages that are characteristic of arthropods . Characteristics of Arthropods All arthropods share characteristics . Arthropods are invertebrates that have an external skeleton , a segmented body , and jointed attachments called appendages . Wings , mouthparts , and legs are all appendages . appendages are such a distinctive characteristic that arthropods are named for it . means joint in Greek , and means foot or Arthropods are into four major groups . major groups of arthropods include crustaceans , arachnids , centipedes and millipedes , and insects Arthropods share some characteristics with many other animals , too . They have bilateral symmetry , an open system , and a digestive system with two openings . In addition , most arthropods reproduce sexually . Outer Skeleton Arthropods have a waxy , waterproof ing called an exoskeleton , or outer skeleton . It protects the animal and helps prevent evaporation of water . Water animals are surrounded by water , but land animals need a way to keep from drying out . Arthropods may have been the animals to live on land Their exoskeletons probably enabled them to do this because they keep the arthropods from drying out . As an arthropod grows larger , its exoskeleton can not expand . The growing arthropod is trapped within its exoskeleton , like a knight in armor that is too small . Arthropods solve this problem by occasionally shedding their exoskeletons and growing new ones that are larger . The process of shedding an outgrown exoskeleton is called molting . After an arthropod has molted , its new skeleton is soft for a time . During that time , the pod has less protection from danger than it does after its new skeleton has hardened . FIGURE 23 A Cicada This cicada has just molted . You can see its old exoskeleton hanging on the leaf just below it . Applying Concepts Why must arthropods molt ?

Chapter 11 435 For Links on arthropods Visit Web Code Fiona 24 Members of the largest arthropod groups differ in several characteristics . Interpreting Tables Which group of arthropods has no antennae ?

body sections Segmented Body The bodies of arthropods are segmented . A segmented body plan is easiest to see in centipedes and , which have bodies made up of many ments . You can also see segments on the tails of shrimp and lobsters . In some groups of arthropods , several body segments become joined into distinct sections . An arthropod may have up to three head , a midsection , and a hind section . Jointed Appendages lust as your are appendages attached to your palms , many arthropods have jointed ages attached to their bodies . The joints in the appendages give the animal and enable it to move . Arthropod appendages tend to be highly specialized tools used for moving , obtaining food , reproducing , and sensing the environment . For example , arthropods use legs to walk and wings to . In addition , most arthropods have appendages called antennae ( singular antenna ) An antenna is an appendage attached to the head that contains sense organs . What Is the function of an antenna ?

Diversity of Arthropods Scientists have more species of one all other species of animals combined ! There are probably many others that have not been discovered . Look at Figure 24 to compare some characteristics of the four major groups of arthropods . Comparisons of the Largest Arthropod Groups Pairs of legs or more Pairs of antennae 4360

Walking Leg A uses its walking legs to crawl . Gills , used to obtain oxygen from the water , are attached at the top of each A uses these , appendages like for swimming . Crustaceans , lobsters , shrimp , and crabs are all examples of crustaceans ( TAY ) A crustacean is an arthropod that has two or three body sections , or more pairs of legs , and two pairs of antennae . Each body segment has a pair of legs or another appendage attached to it . The various types of appendages function , as you can see in Figure 25 . Crustaceans live in watery environments . Therefore , most use gills to obtain oxygen . The gills are protected by the exoskeleton . Water containing oxygen reaches the gills as the crustacean moves along . Most crustaceans , such as crabs and shrimp , begin their lives as tiny swimming larvae . Crustacean larvae develop into adults by metamorphosis . Metamorphosis ( met uh sis ) is a process in which an animal body undergoes dramatic changes in form during its lifetime . walking leg under the shell . Two large antennae ?

to smell , taste , and touch . i Antenna Sense organs for taste , touch , and balance are located on two small , forked antennae . The crayfish uses i to capture i food and to defend itself . FIGURE 25 Crayfish Appendages A appendages are as varied as the tools on a Swiss army knife . The appendages are adapted for different functions . Interpreting Diagrams What functions do the serve ?

Chapter 11 431 FIGURE 26 Red Knee Tarantula This red knee tarantula lives in an underground burrow . The spider uses fangs to inject venom into its prey . FIGURE 27 Centipede Centipede have many pairs of legs . Interpreting Photographs How many pairs of legs does each segment of the centipede have ?

438 Arachnids Spiders , mites , ticks , and scorpions are the arachnids ( uh RAK ) that people most often meet . Arachnids are arthropods with two body sections , four pairs of legs , and no antennae . Their first body section is a combined head and midsection . The hind section . called the abdomen , is the other section . The abdomen contains the reproductive organs and part of the digestive system . Spiders are probably the most familiar . most feared , and most fascinating kind of arachnid . All spiders are predators , and most of them eat insects . Spiders have hollow fangs through which they inject venom into their prey . Spider venom turns the tissues of the prey into mush . Later the spider uses its fangs like drinking straws . and sucks in the food . In spite of what some people might think , spiders rarely bite people . When spiders do bite , their bites are often painful but rarely . However . the bite of a brown recluse or a black widow may require hospital care . Centipedes and Millipedes Centipedes and millipedes look something like earthworms . However , they are arthropods , not Worms . and millipedes are arthropods with two body sections and many pairs of legs . The two body sections consist of a head with one pair of antennae , and a long abdomen with many segments . Centipedes have one pair of legs attached to each segment . Some centipedes have more than 100 segments . In fact , the word centipede means hundred Millipedes , which may have more than 80 segments . have two pairs of legs on each segment . Though millipede means thousand feet , millipedes don have that many legs . i Em How many sections does an arachnid body have ?

FIGURE 28 Structure of a Grasshopper A grasshopper body , like that of every . has three sections . Head Thorax Abdomen Characteristics of Insects By far the most common of all the arthropods are the insects . You can identify insects , like other arthropods , by counting their body sections and legs . Insects are arthropods with three body sections , six legs , one pair of antennae , and usually one or two pairs of wings . The three body sections are the head , thorax , and abdomen , as you can see in Figure 28 . Head An insect brain and most of its sense organs , such as the eyes and antennae , are in its head . The brain , antennae . and eyes are organs that are part of a nervous system . Each organ , tissue . and cell inthis system contributes to the function of sensing the environment and directing body activities . For example , insects usually have two large compound eyes , which enable them to see their surroundings . These eyes contain many lenses . Each lens is a structure that focuses light and forms images . Compound eyes are especially keen at seeing movement . Most insects also have simple eyes that can distinguish between light and darkness . Thorax An insect midsection , or thorax , is the section to which wings and legs are attached . Most insects can once they are adults . insects are the only invertebrates that can . Abdomen inside the abdomen are many of the insect nal organs . Small holes on the outside of the abdomen lead to a system of tubes inside the insect . These tubes allow air , which contains oxygen , to enter the body . The oxygen in the air travels directly to the insect cells . Activity Graphing Use the data to make a circle graph that shows the percentage of total insect species in each group . See the Skills Handbook . Chapter 11

FIGURE 29 Insect Metamorphosis Depending on the , most insects develop adults through or Female fireflies lay their eggs In moist places . The eggs of glow in the dark . i ) gradual 10 sis . II Complete Metamorphosis Adult when . complete , an adult out pupal case . and . Adult , Insect Life Cycles The eggs hatch into larvae that feed on snails and slugs . After a time , the firefly larva becomes a pupa . inside the protective pupal case , wings , legs , and antennae form . insects hatch from eggs . They then develop through phosis . Each insect species undergoes either complete metamorphosis or gradual metamorphosis . Complete Metamorphosis In Figure 29 you can see that an insect with complete metamorphosis has four different stages egg , larva , pupa , and adult . Eggs hatch into larvae . The larvae , such as the caterpillars of butterflies , usually look thing like worms . larvae are specialized for eating and ing . After a time , a larva becomes a pupa ( puli ) Major changes in body structure are taking place in this stage , as the pupa becomes an adult insect . Beetles , and ate ants all undergo complete metamorphosis . Gradual Metamorphosis In contrast . the second type of metamorphosis , called gradual metamorphosis , has no dis tinct larval stage . An egg hatches into a stage called a nymph ( which usually looks like the adult insect without wings . A nymph may molt several times before an adult . Grasshoppers , termites , cockroaches , and go through gradual .

uh A female grasshopper tip emerges from the final molt ( with slud wings . Once Its wings have hardened . the adult mate and begin the cycle again . Eggs hatch Into nymphs that look much like miniature adult except thatthey have no wings , or only small ones . humor Nymph A nymph feeds until its exoskeleton becomes too tight . and then it . The nymph molt four or . five times before becoming an adult . section Assessment Vocabulary Skill Use Clues to Determine a . Listing List the stages of gradual Meaning Find the Key Term thorax on page metamorphosis and the stages of complete What does thorax mean ?

What clues help you metamorphosis . understand its meaning ?

Interpreting Diagrams Look at Figure 29 . How are complete metamorphosis and Reviewing Key Concepts Identifying What are the characteristics of arthropods ?

Explaining What structure protects an arthropod body from loss of water ?

rub Relating Cause and Effect Why does an an Al ' insect body need this protection ?

a . Listing List the mam groups of arthropods . Interpreting Tables Use Figure 24 to contrast the number of body sections in the major groups of arthropods . Applying Concepts In which section are most of an insect sense organs located ?

What organ system are the sense organs a part of ?

gradual metamorphosis different ?

Bug Hunt Walk with a family member in your backyard or neighborhood . Search the undersides of leaves , under or rocks , and other likely places for insects . Show your family member what distinguishes an insect from other kinds of arthropods . 11 441 Invertebrates on Branches . Problem How can you construct a branching tree diagram to classify some Wings invertebrates ?

Skills Focus classifying , interpreting data Exoskeleton Common ancestor Materials index cards Procedure Review the explanation of a branching tree diagram in Chapter . Recall that in a ing tree diagram , the organism with none of the characteristics goes at the bottom of the tree . The organism with the greatest number of derived characteristics goes at the top . Examine the incomplete branching tree diagram . Copy it in your notebook . The table below lists characteristics of five invertebrates . Make a card for each animal that lists the characteristics of that animal . Then arrange the cards in order , beginning with the animal that has none of the and ending with the animal that has all the characteristics . Use the data in the table and your cards to complete the branching tree diagram . Put the missing animals on their correct branches . Identify the missing characteristics . Earthworm . You discover a fossil scorpion similar to the one in the photograph . The fossil animal has an exoskeleton but does not have three body sections . Mark on your copy of the branching tree diagram where the scorpion should go . Analyze and conclude . Classifying Which animal goes at the top of the diagram ?

How many of the listed does the animal have ?

Interpreting Data Except for the earthworm , all the animals in the table belong to the same phylum . To which phylum do these mals belong ?

Drawing Conclusions Which animal in the table is most closely related to the fossil scorpion ?

Explain how you know this . Communicating Which two animals on the diagram are most distantly related ?

Write a paragraph in which you identify the data on which you base your conclusion . More to Explore Do research to learn some of the characteristics that are used to classify insects into groups . Write a report about what you have learned . Characteristics of Some Invertebrates Butterfly

Section Students know the between the cycles and reproduction methods of sexual and asexual organisms . Students know organ function because of the of individual organs , tissues , and cells . The failure of any part can affect the entire system . What are the main characteristics ' of What are the major groups of ?

Key Terms echinoderm endoskeleton water vascular system tube feet I . How Do Sea Stars Hold On ?

Use a plastic dropper and water to model how a sea star moves and clings to surfaces . Fill the dropper with water , and then squeeze out most of the water . Squeeze the last drop of water onto the inside of your arm . Then , while squeezing the bulb , touch the tip of the dropper into the water drop . With the dropper tip against your skin , release the bulb . Hold the dropper by the tube and lift it slowly , paying attention to what happens to your skin . Think it Over Predicting Besides moving and clinging to surfaces , what might sea stars use their suction structures for ?

While exploring a rocky beach one day , you see what looks like a dill pickle at the bottom of a tide pool . You think it might be a plant or a rock covered with green slime . But as you look more closely , the pickle begins to crawl very slowly . This ing creature is a sea cucumber , a relative of sea stars . Characteristics of Sea cucumbers , sea stars , sea urchins , and sand dollars are all ( ee KY noh ) members of the phylum . are invertebrates with an internal skeleton and a system of tubes called a water vascular system . All live in salt water . Body Structure The skin of most is stretched over an internal skeleton , or endoskeleton , made of hardened plates . These plates support the animal and give it a bumpy texture . Adult have a unique kind of radial in which the body parts , usually in multiples of , are arranged like spokes on a wheel . Chapter 11

Go for Water Vascular System activity Visit Web Code mun so A Water Vascular System , such as this sea star , have a water vascular system that helps them move and catch food . Interpreting Diagrams Where does water enter the water vascular system water Vascular System The sea star water vascular system extends into each one of its arms . Movement The internal organ system of tubes in is called the water vascular system . You can see a sea star water vascular system in Figure 30 . Portions of the tubes in this system can contract , or squeeze together , forcing water into structures called tube feet . This process is something like moving water around in a water balloon by squeezing ferent parts of the balloon . The ends of tube feet are sticky . When with water . they act like small , sticky suction cups . The stickiness and tion enable the tube feet to grip the surface beneath the . Most use their tube feet to move along slowly and to capture food . Reproduction and Life Cycle Almost all are either male or female . Eggs are usually fertilized in the water , after a female releases her eggs and a male releases his sperm . The fertilized eggs develop into tiny , swimming larvae that look very different from the adults . The larvae eventually undergo metamorphosis and become adult . Reading What are the functions of an tube feet ?

Tube Feet tube feet line the underside of a sea star arms and act like tiny suction cups . In a sea star . water enters . the water vascular system partly through an opening in this round plate .

Diversity of There are four major groups of sea stars , sea urchin brittle stars , sea urchins , and sea cucumbers . The members of these groups look quite different . They also have different ways of feeding and moving . Sea stars are predators that eat mollusks , crabs , and even other . Sea stars use their tube feet to move across the ocean floor . They also use their tube feet to capture prey . A sea star will grasp a clam with all arms , and then pull the shells open . Then the sea star feeds on the clam tissues . A brittle star arms are long and slender . To move , a brittle star waves its arms in a snakelike motion against the ocean floor . A brittle star uses its tube feet to catch food . sea Cucumber Sea urchins have no arms . Spines cover and protect their mu bodies , so they look something like a pincushion . To move , sea Diversity of urchins use tube feet that extend out between the spines . They scrape and cut food with five toothlike structures . are diverse in their Sea cucumbers look a little bit like the cucumbers you eat . appearance but all have With tube feet on their underside . sea cucumbers crawl along symmetry and are found in the ocean . They feed with a mouth surrounded by tentacles . the I . Writing . Section Assessment Vocabulary Skill Use Clues to Determine Meaning A Look at the of endoskeleton on page 443 . What writing I Ce . phrase in the sentence gives the meaning of endoskeleton ?

comparison In a Reviewing Key Concepts comp . and a . Reviewing What characteristics do have ?

how , ma Summarizing Explain how reproduce . Inferring In , could fertilization take place without water ?

Why or why not ?

Identifying Identify the four major groups of . Comparing and Contrasting Compare and contrast how sea stars and sea urchins feed . Predicting Would a sea star be able to eat clams without using its tube feet ?

Explain . Chapter 11 445 Chapter 11 Study Guide TI 19 I a The structures of animals bodies enable them to obtain food and oxygen , keep internal conditions stable , move , and reproduce . what Is an Animal ?

Key Concepts The cells of most animals are organized into tissues , organs , and organ systems . Some major functions of animals are obtaining food and oxygen , keeping internal conditions stable . moving , and reproducing . Symmetry is a balanced arrangement of body parts that is characteristic of many animals . Animals are according to how they are related to other animals . Key Terms anatomy physiology bilateral symmetry radial symmetry invertebrate phylum Sponges and Key Concepts . Sponges are invertebrates that usually lack symmetry and never have tissues or organs . use stinging cells to capture food and defend themselves . Key Terms larva cnidarian polyp medusa Worms and Mollusks Key Concepts , All worms are invertebrates that have long , narrow bodies without legs . Unlike or flatworms , have a digestive system that is like a tube , open at both ends . Segmented worms have bodies made up of many linked sections called segments . In addition to a soft body often covered by a shell , a mollusk has a mantle and a foot . The three major groups of mollusks are . bivalves . and cephalopods . 4460 Key Terms brain parasite host anus closed circulatory system mollusk open circulatory system gill gastropod radula bivalve cephalopod Arthropods Key Concepts . Arthropods are invertebrates that have an external skeleton , a segmented body , and jointed attachments called appendages . The major groups of arthropods are crustaceans , arachnids , centipedes and millipedes , and insects . A crustacean is an arthropod that has two or three body sections , or more pairs of legs , and two pairs of antennae . Arachnids are arthropods with two body sections , four pairs of legs , and no antennae . insects have three body sections , six legs , one pair of antennae , and usually one or two pairs of wings . Each insect species undergoes either complete metamorphosis or gradual metamorphosis . Key Terms arthropod exoskeleton molting antenna crustacean metamorphosis arachnid abdomen insect thorax complete metamorphosis pupa gradual metamorphosis nymph Key Concepts , are invertebrates with an internal skeleton and a system of tubes called a water vascular system . Groups of include sea stars , brittle stars , sea urchins , and sea cucumbers . Key Terms echinoderm water vascular system tube feet

Go For Visit Web Code Review and Assessment Target Reading Skill Take Notes To review part Section , take notes on the text following the heading Movement . Copy the incomplete graphic organizer shown on the right . Complete it by answering the questions . Reviewing Key Terms Choose the letter of the best answer . An animal without a backbone is called a ( Complete the following sentences so that your answers clearly explain the key terms . vertebrate . A sea anemone is a described as a polyp invertebrate . because its body is . larva . Unlike the blood in an open circulatory system , the blood in a closed circulatory . Which group of animals uses stinging cells to system ' A gastropod has a radula . which is vertebrates a ( mans 10 . An insect body is protected by its ( Sponges exoskeleton which is a ( Which organ do most mollusks and crustaceans use to obtain oxygen ?

11 . Unlike gradual metamorphosis , complete metamorphosis has radula lungs gills Writing in Science . An arthropod antennae are located on its ' head are covering a ' a ' has washed up on the local beach . Writes short news story describing the discovery . At which stage of insect development do major changes in body structure occur ?

an . egg larva haul Saul . move by using structures called . Arthropods . wings . appendages . tube feet . abdomens . sure to describe how scientists the animal as a squid . Chapter 11 441 Review and Assessment Checking Concepts 12 . Explain the relationship among cells , tissues , and organs . 13 . What are five key functions of animals ?

14 . Explain what a digestive system is . 15 . Describe the structure of a mollusk gills . 16 . Contrast the functions of an compound eyes and simple eyes . 17 . What is an endoskeleton ?

What is its function ?

Thinking Critically 18 . Making Judgments Suppose a book is called Earth Animals . All the animals in the book are vertebrates . Is this title a good one ?

Explain your reasoning . 19 . Classifying Classify each of the following animals as having radial symmetry , bilateral symmetry , or no symmetry sea anemones . sponges , fishes , humans . and . 20 . Classifying Which of the animals below is a roundworm ?

A sponge ?

A cnidarian ?

Describe the major characteristics shared by members of each phylum . It 21 . Comparing and Contrasting Compare and contrast bivalves and cephalopods . 22 . Applying Concepts Explain why the development of a lion , which grows larger as it changes from a tiny cub to a adult , is not metamorphosis . 23 . Applying Concepts Some seafood restaurants serve a dish called crab . What do you think happened to the crab just before it was caught ?

Why is this process important ?

4480 24 . Classifying Your friend said he found a dead insect that had two pairs of antennae and eight legs . this possible ?

Why or why not ?

25 . Comparing and Contrasting Compare and contrast centipedes and millipedes . Applying Skills Use the data table to answer Questions . The following data appeared in a book on insects . Flight Characteristics moth Bumblebee Housefly 26 . Graphing Use the data to make two bar graphs one showing the three insect rates and another showing the speeds 27 . Interpreting Data Which of the three insects has the highest rate ?

Which insect the fastest ?

28 . Drawing Conclusions Based on the data , is there a relationship between the rate at which an insect beats its wings and the speed at which it ?

Explain . What factors besides rate might affect flight speed ?

Standards Investigation Performance Assessment Prepare a display to show how you set up your experiment and what your results were . Construct and display graphs to show the data you collected . Include pictures of the mealworms in each stage of development . Write your conclusion of how the experimental conditions affected the growth and development of the mealworms . Also suggest some possible explanations for your results .

Standards Practice Choose the letter of the best answer . What is the correct sequence in which a stinging cell reacts to the touch of another organism ?

A trigger brushes against prey , stinging cell , barbs snare prey barbs snare prey , stinging cell , barbs release prey prey is paralyzed . venom enters prey . stinging cell tentacles pull prey to mouth , prey is ingested , stinging cell fires . Which of the following is true of a digestive system ?

A It is found in all parasites . It has two openings . It has one opening . It is found in all parasites and has one opening . Use the diagram below and your knowledge of science to answer Question . Of the four animals above , which have sense organs concentrated at one end of their bodies ?

A animals A and animals A , and animals and animals A . and at . Which of the following statements is true about gradual metamorphosis ?

A Gradual metamorphosis is a life cycle that involves asexual reproduction . In gradual metamorphosis , a larva develops into a pupa . In gradual metamorphosis , an egg hatches into a nymph . Gradual metamorphosis has four distinct stages . Use the diagram below and your knowledge of science to answer Question . You are constructing a branching tree diagram that shows the relationship between animals A and above . Which of the following characteristics could you use to place the two animals on different branches ?

A type of circulatory system presence or absence of jointed appendages type of digestive system presence or absence of antennae . Which of the following best describes the stages in the sexual life cycle of a sponge in the correct order ?

A larva , fertilization , egg and sperm , adult adult , larva , egg and sperm , fertilization adult , bud , bud breaks free egg and sperm , fertilization , larva , adult . Explain how a sea star water vascular system enables the sea star to move . Chapter 11 us