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How are animals different from one another? Essential Questions Lesson I How do animals compare? Lesson 2 Which animals have backbones? Lesson 3 How do systems help animals survive? Lesson U How do animals grow and reproduce? Chobe National Park, Botswana yaamaa* Big Idea Vocabulary invertebrate an animal w ith o u t a backbone (p. 79) vertebrate an animal w ith a backbone (p. 90) muscular system the organ system m ade up o f muscles th a t m ove bones (p . 1 0 0 ) digestive system the organ system th a t breaks dow n fo o d fo r fuel (p. 104) metamorphosis a life cycle including fo u r stages o f g row th : egg, larva, pupa, and adult ( p . 112) heredity the passing o f tra its fro m parent to o ffsp rin g (p. 114) V is it www.macmillanmh.com fo r o n lin e re so u rce s. Lesson 1 Animals without Backbones garden snails Look and Wonder Here is a riddle. W hat has thousands of teeth one foot, and no backbone? A snail, that’s what! W hich other animals lack a backbone? Explore Inquiry A ctivity What makes an earthworm an animal? M a te ria ls Make a Prediction W hat characteristics does an earthw orm have that make it an animal? Make a prediction. Test Your Prediction O 0 Take the earthw orm out of the terrarium. Place it on a dam p paper towel. W hat does the earthw orm do? W atch how it moves. Record your observations. • living earthworm • soil • leaves damp paper towel Observe Gently touch the w orm w ith your finger. W atch w hat happens. Record your observations. O Observe A fter a few days, observe the terrarium. Do you notice any changes in the e a rth w o rm ’s environment? Draw Conclusions O Communicate How did the earthw orm respond when you touched it? 0 Infer Does the earthw orm have a skeleton? How can you tell? <0 W hat characteristics does the earthw orm have th a t make it an animal? More Observe other kinds of animals. Do they have the same characteristics as the earthworm? "s.'-'- Earthworm Observations How it moves W hat happens when tou ch e d How th e environment chang€$ EXPLORE What are invertebrates? E s se n tial Q u e s tio n How do animals compare? ^ V o c a b u la ry invertebrate, p. 79 sponge, p. 80 cnidarian, p. 80 mollusk, p. 81 echinoderm, p. 81 endoskeleton, p. 81 arthropod, p. 82 One difference between animals is how their O Main Idea and Details Main Idea y One way to describe animals is by their similarities and differences. How are animals similar? All animals are made of many cells. M ost animals can move on their own. Like all living things, animals grow, change, reproduce, and respond to their environment. They get the energy they need from eating food. Symmetry exoskeleton, p. 82 ^ R e a d in g S k ill How would you describe animals? Think about your pets, your friends’ pets, or animals in a zoo. D on’t forget that you are an animal too. D etails bodies are shaped. M ost animals have symmetry (S IH » m u h *tre e ). Symmetry means that parts of the animal’s body match up with other parts around a midpoint or line. Some kinds of animals have no symmetry. T e c h n o lo g y e -G lossary and e-Review online at www.macmillanmh.com ▲ A sea urchin has symmetry. < A sponge is the simplest kind of animal. It does not have symmetry. In verteb rate Groups mollusks cnidarians flatworms roundworms echinoderms segmented worms arthropods Read a Photo ^ Backbone or No Backbone Another way that animals differ is whether they have a backbone. A vertebrate ( V U R » tu h * b ra y t) is an animal that has a backbone. An animal without a backbone is an Which animal grou p does not have symmetry? Clue: Look at each animal. See whether the parts c>n one side match up with the parts o i the other side. invertebrate (in * V U R » tu h * b ra y t). More than 95 out of every 100 animals are invertebrates. They come in all shapes and sizes. Some, like ants and earthworms, can fit in your palm. Others can grow much larger. Some have a hard, outer covering. Others have a support structure inside their bodies. The chart shows the eight main groups of invertebrates. y|Quick Check Main Idea and Details What are two ways in which animals differ? Critical Thinking Could an animal with a backbone have no symmetry? Explain. 79 EXPLAIN Q uick Lab How Jellyfish Move O Make a Model Blow up a balloon. Hold the end of the balloon tig h t so the air cannot escape. The balloon models the hollow shape of a jellyfish. The air inside represents water that fills the animal’s body. ^ W hat do you think will happen when you let go of the balloon? O Observe Let go of the balloon. W hat happens? How does this model the way a jellyfish moves? What are some invertebrates? Sponges A sponge is the simplest kind of invertebrate. Sponges do not have symmetry. Sponges live underwater. M ost are shaped like a sack, with an opening at the top. Water flows into the sponge. It filters the water for food. The adults stay in one place. Their offspring float or swim. Cnidarians A cnidarian (n i*D A Y R *e e *u n ) is an animal with armlike parts called tentacles (T E N » tih *k u lz ). At the tip of each tentacle are poisonous stinging cells. Cnidarians use these cells to stun prey. Jellyfish and corals are cnidarians. Corals are cnidarians. Mollusks Do you collect seashells? Those shells come from invertebrates with soft bodies. These invertebrates are mollusks. M ost mollusks have shells and live in water. Snails and slugs are the only mollusks that live on land. Some adult mollusks, such as clams and oysters, stay attached to one place. Others, such as squid and octopuses, swim freely. The fileclam is a mollusk that lives among coral reefs. Echinoderms Sea urchins are echinoderms (ih * K I* n u h * d u rm z ). An echinoderm has spiny skin. It also has an internal support structure. This structure is called an endoskeleton (E N *d oh »S K E »lu h*tun ). Quick Check Main Idea and Details What do sponges, cnidarians, mollusks, and echinoderms have in common? Critical Thinking Why do you think all sponges live underwater? Before and A fte r Read a Photo W hat happens to an octopus when it is threatened? Clue: Look at the color and shape of the octopus in both pictures. EXPLAIN What are arthropods? " These anim als are all insects. The largest invertebrate group is arthropods (A R « th ru h » p o d z ). Arthropods have jointed legs and a body that is divided into sections. Some, like crabs and shrimps, breathe with gills. Others, like insects and some spiders, breathe through open body tubes. Every arthropod has an exoskeleton (E K *soh*S K E *luh«tun). This is a hard A covering that protects the body. It also keeps in moisture so the animal doesn’t dry out. Lobsters, bees, and scorpions are arthropods. Insects are by far the largest arthropod group with almost one million species. Centipedes and millipedes are relatives of the insects. Quick Check Main Idea and Details What are the features that all arthropods share? Critical Thinking Are all insects arthropods? Are all arthropods insects? Explain. face beetle praying mantis Many a rth ro p o d s shed th e ir exoskeletons so th e y can g ro w bigger. EXPLAIN moth A rth ro p o d Groups Insects Arachnids Arachnids (uh*RAK«nudz) include spiders, ticks, and scorpions. They have four pairs of legs, two body sections, and fangs. weaver ant Insects have one pair of antennae, three pairs of legs, one or two pairs of wings, and three body sections. Crustaceans huntsman spider Centipedes and Millipedes Centipedes have one pair of legs on each body section. A millipede has two pairs of legs on each body section. fiddler crab Crustaceans (krus*TAY*shunz), such as crabs and shrimps, have two pairs of antennae and two to three body sections. They can chew. EXPLAIN How are worms classified? You may think all worms look alike, but there are several groups. Three of these are flatworms, roundworms, and segmented worms. Flatworms True to their name, flatworms have flat bodies. They have a head, simple eyes, and a tail. Flatworms are the simplest worms. M ost are harmless. Some live inside the bodies of other animals. Segmented Worms Earthworms, sandworms, and leeches are segmented worms. Their bodies are divided into segments. The segments are identical, except for the head and tail ends. Each end has an opening for the digestive system. M ost segmented worms live on land. Unlike flatworms and roundworms, there are few segmented worms that live inside another animal’s body. < A planarian is a flatworm. Roundworms Roundworms have thin bodies with pointed ends. They are not as thin as flatworms. Roundworms have a one-way digestive system. Food comes into one opening. Wastes leave through another. M ost roundworms live inside the bodies of other animals. A nematode is a roundworm. ► Quick Check Main Idea and Details Describe the three groups of worms. ▲ An earthworm is a segmented worm. 84 EXPLAIN Critical Thinking Where do worms that live inside the bodies of other animals get their food? Lesson Review ^ d Think, Talk, and W rite Visual S u m m ary Invertebrates—such as sponges, cnidarians, echinoderms, and mollusks—are animals w ith o u t backbones. 0 Vocabulary W hen one side of an animal matches up exactly w ith the other side, that animal h a s ________ 0 Main Idea and Details W hat are the advantages of having an exoskeleton? The disadvantages? The largest invertebrate group is arthropods. They have jointed legs and a bo dy that is divided into sections. Main Idea Critical Thinking W hy do soft 0 The three main groups of worms are flatworms, roundworms, and segmented worms. D etails animals like sponges and cnidarians not live on land? 0 Test Prep Which is an invertebrate? A eagle B fish c snake M ake a S tu d y G u id e D s h rim p Invertebrates Make a three-tab book. Use it to summarize what you learned about animals w ith o u t backbones. Test Prep Which characteristic do 0 mollusks and arthropods share? a They have backbones. b They d o n o t have backbones, c They have exoskeletons. D They d o n o t move. Worms Essential Question How do animals 0 compare? n W ritin g L ink W rite a Story Choose an invertebrate from this lesson. W rite a story from its point of view. Tell w hat it is like to live the life of this animal. « It l^ - R e v ie w A r t L ink Make a Poster Make a poster that shows the major invertebrate groups. Use drawings or photographs. Label each group. S u m m a rie s and q u iz z e s o n lin e a t www.macmillanmh.com 85 EVALUATE Focus on Skills L _______________ inquiry skill: Classify You k n o w th a t som e anim als are v e rte b ra te s and oth e rs are in vertebrates. This g ro u p in g d e p e n d s on w h e th e r an anim al has a ba ckb o n e . Scientists group, o r classify, living th in g s based on th e tra its th e y share. jellyfish One w a y to classify anim als is by th e presence o f a ba ckbo ne . You can also classify anim als by o th e r traits, such as s ym m e try. S y m m e try describes h o w th e b o d y pa rts are arranged. ► Learn It W hen you classify, you place things that share properties into groups. Classifying is a good way to organize data. You can probably rem em ber the properties of a few groups. It Is harder to rem em ber those properties when you have thousands of groups! It is im po rta nt to keep go od notes when you classify. Your notes can help you see w hy things belong in the same group. They also help you classify things in the future. ► Try It Classify animals by their symmetry. Most animals, like butterflies, have b ilatera l (b i*L A *tu h *ru l) symmetry. This means that their tw o sides are alike. Others, like sea stars, have radial (RAY«dee«ul) symmetry. That means their bo d y parts stretch out from a central point. A few animals have no sym m etry at all. Look at each animal pictured on these pages ^ W rite each animal’s name on a chart like the one shown. ^ Mark an X on the chart to show the kind of sym m etry each animal has. 86 EXTEND June beetle Skill Builder M s O b s e r v a t io n s too Bilateral fodia.1 Animal Symmetry Symmetry' June beetle fe<\ Fox barrel sponge ~ . j* 9SSSIÉ ¡1 ► Apply It 0 0 Study the data on your chart. How many animals have radial symmetry? Bilateral symm etry? How many animals have no symmetry? Look at magazines or books for photos of animals. A dd them to your chart or make a new chart to com pare them. | 0 Classify the sym m etry of each new animal. Try to find at least one animal that shows each ty p e of symmetry. 0 Now classify all the animals in a new way. Use size, color, or any other prope rty you choose. Share your findings w ith the class. W -V I Lesson 2 Elephants are the largest land animal. The males can weigh as much as 6 ,8 0 0 kilograms (1 5 ,0 0 0 pounds)! Nearly all the large animals in the world have something in common that helps support their weight. Do you know what it is? Explore What does a backbone do? Inquiry A ctivity M a te ria ls Make a Prediction W hich can support more w e ig h t—an animal w ith a backbone or one w itho ut? Make a prediction. Test Your Prediction 0 Make a Model Using clay, make a model of an animal w ith four legs but no backbone. Q • modeling clay • pencil Now make an identical clay model, this tim e w ith a backbone. Make your model the same size and shape as the first. Assemble the “ backbone” by m olding clay around a pencil. ( 0 Observe Use balls of clay to add w eigh t to your models. How much w eigh t can each model hold before it breaks? Draw Conclusions 0 W hich model supported the w eight b e tte r— the one w ith a backbone or w itho ut? 0 W hat advantage does a backbone give to a land animal? <0 Infer W hat advantage w ould a backbone I! ' give to an animal that lives underwater? Explore More Make a third model that uses pencils for the legs and the backbone. How does your new model compare to the others? W hat do the pencils in the legs represent? 89 EXPLORE 4 Read » and Learn What are vertebrates? k Essential Question Which animals have backbones? Vocabulary vertebrate, p. 90 warm -blooded, p. 90 cold-blooded, p. 90 Did you know that you are part of the same large group as fish, frogs, snakes, birds, and mice? Each has a backbone, and so do you! A backbone is what makes vertebrates different from invertebrates. The backbone is an important part of a vertebrate’s endoskeleton. It supports the animal’s body. A backbone allows larger and heavier animals to move about. amphibian, p. 92 reptile, p. 92 bird, p. 93 mammal, p. 94 ► Reading Skill G C o m p are and Contrast D iffe re n t A like D iffe re n t Technology e-G lossary and e-Review online at www.macmillanmh.com Some vertebrates, such as birds and mammals, are warm -blooded. Their body temperature does not change much. These animals get heat from breaking down food. This helps them keep a constant body temperature. Fish, amphibians, and reptiles are cold-blooded. They cannot keep constant body temperatures. Instead, their body temperatures change with their surroundings. Cold-blooded animals get heat from outside their bodies. Vertebrates are grouped into seven classes. These are jawless fish, cartilaginous (k a r» tu h « L A *ju h » n u s) fish, bony fish, amphibians, reptiles, birds, and mammals. Can you spot the backbone of this fish? 90 EXPLAIN Classes o f V ertebrates Fish The three classes of fish are jawless, cartilaginous, and bony fish. The first two have skeletons made of cartilage ( K A R - tu h - lij) . Cartilage is the same rubbery material that is in your outer ears or the tip of your nose. cartilaginous fish Jawless fish have boneless mouths. The mouth acts like a suction cup. Lampreys are one example. Cartilaginous fish include sharks and rays. reptiles The largest class of vertebrates is the bony fish. Their skeletons are made of bone, and they are covered in scales. Tuna and goldfish are bony fish. jawless fish Quick Check Com pare and Contrast How are the three classes of fish alike? How are they different? amphibians Critical Thinking Why might warm-blooded vertebrates eat more often than cold-blooded vertebrates? Read a C h a r t ') -------------------------------------Which vertebrate groups are warm-blooded? Which are cold-blooded? Clue: Look at the colors of the labels. birds_______ | mammals_____ | 91 EXPLAIN What are some other vertebrate groups? Amphibians Frogs, toads, and salamanders are amphibians (a m » F IH *b e e *u n z ). A m p h ib ia n s are cold-blooded vertebrates that spend part of their lives in water and part on land. Like all amphibians, a frog begins its life in water. Frog eggs hatch into tadpoles. Tadpoles have gills that allow them to live in water— but not on land. As they grow, these parts change. The tadpoles grow lungs. This allows the adults to live on land. Reptiles Lizards, snakes, turtles, and alligators are reptiles (R E P *tile z). R e p tile s are cold-blooded vertebrates that live on land. Unlike amphibians, reptiles have dry skin. Their skin is covered with plate-like scales. This strong, w aterproof covering helps reptiles live on land. Reptiles cannot breathe through their skin. They use lungs. When they reproduce, a tough cover keeps their eggs from drying out. An amphibian’s skin needs to stay moist. Even though it has lungs, the adult also breathes through its skin. If the skin dries out, the animal will not survive. That is why most amphibians live near water. Am phibians and Reptiles Read a Photo How are the frog and lizard different? Clue: Observe the surroundings of each animal. EXPLAIN How Birds Fly 0 Measure Cut a strip of paper ab out 5 centim eters w ide and 20 cm long. 0 Make a Model Put the to p 2 cm of the strip between the cover and the first page of an open book. Close the book. The paper models a wing. 0 Hold the bo ok near your mouth w ith the long side horizontal. Gently blow across the to p of the paper. 0 W hat happens to the paper when you blow across it? 0 Infer The shape of a b ird ’s w ing is like an airplane wing. How m ight this shape help birds fly? Birds are the only animals that have feathers. Girds Birds are warm-blooded vertebrates with feathers. Feathers are light, yet they keep birds warm and dry. Birds also have beaks and two legs with clawed feet. Their feet have scales, like reptile skin. Even though all birds have feathers, not all birds can fly. For birds that do fly, other traits come in handy. Light, hollow bones help. So do powerful lungs. The shape of their wings and strong flight muscles help them lift off the ground. Birds lay eggs with strong shells. M ost birds keep their eggs warm by sitting on them until they hatch. Reptile skin is dry, n o t slimy. J Quick Check Com pare and Contrast How do the body coverings of amphibians, reptiles, and birds compare? Critical Thinking Would a lizard be able to live in a very cold environment? Why or why not? 93 EXPLAIN What are mammals? Did you know that you are a mammal? A mammal is a warm-blooded vertebrate with fur or hair. Mammals can live in trees, water, and most other places on Earth. Mammals care for their offspring. The three main groups of mammals are classified by how the young are born. M ost give birth to live young. But some lay eggs. Females produce milk to feed their young. y)Quick Check Com pare and Contrast How do mammals differ from each other? How are they alike? Critical Thinking A scientist discovers a new animal. She thinks it may be a mammal. How can she be sure? The loris is a mammal with a good sense of sight. Groups o f Mam m als Mammals That Lay Eggs The only mammals that lay eggs are the duck billed platypus and the spiny anteater. Mammals with Pouches Kangaroos, koalas, and opossums carry their young in pouches until the young are grown. Mammals That Develop Inside Sheep, bats, apes, and all other mammals develop inside the m other’s body. 94 EXPLAIN L. Lesson Review Think, Talk, and W rite Visual S u m m ary Vertebrates are animals w ith backbones. They can be w arm -blo ode d or cold-blooded. There are seven classes. <0 Vocabulary A ________-blooded animal uses heat from its surroundings to stay warm. 0 Compare and Contrast How are the seven classes o f vertebrates alike? How are they different? Fish, amphibians, and reptiles are c o ld blooded. Birds are w a rm -blo ode d and have feathers. Mammals are w a rm blooded and have hair or fur. The young develop in three different ways. D iffe re n t A lik e D iffe re n t | 0 Critical Thinking A newt looks like a lizard, but it is really an amphibian. W hat traits must a newt have? Test Prep Birds and mammals most likely M ake a S tu d y G u id e Make a layeredlook book. Use it to summarize what you learned about animals w ith backbones. A a have b a ck b o n e s and give milk. b have b a c kb o n e s and lay eggs, c have b a c kb o n e s and look afte r th e ir young. A nim als with B a c k b o n e s V ertebrates d 0 lay eggs and are c o ld -b lo o d e d . Essential Question W hich animals have backbones? F is h , a m p h ib ia n s , reptiles,and birds Mammals Hath Link Writing Link W rite a Story W hat vertebrates live in your neighborhood? Choose one. W rite a paragraph that explains w hat kind of vertebrate it is. Include its characteristics. RGViPW Solve a Problem A blue whale can weigh 100 tons. One ton equals 2 ,0 0 0 pounds. How many pounds does the blue whale weigh? How many times heavier than you is the blue whale? S u m m a rie s a nd q u iz z e s o n lin e a t www.macmillanmh.com ______ 95 EVALUATE Writing in Science Manatees are ve ry large m a m m a ls th a t live in th e water. These g e n tle giants live in Florida. M anatees are endangered. This m eans th e re are ve ry fe w left. Scientists are w o rrie d th a t th e y m ig h t die out. H ow d id this happen? Manatees live along th e coast, w h e re Explanatory Writing Good explanatory writing ► explains how to do a task or how something happened; ► gives clear details that are easy to follow. p e o p le o fte n g o b o a tin g . These anim als are curious, b u t th e y m o ve ve ry slowly. S o m e tim e s th e y c o m e close to p e o p le in bo ats and b u m p in to the m . Many have been h u rt o r killed by b o a t propellers. People bu ild th in g s a lon g th e coast. W rite About It Explanatory W riting Find o u t m o re a b o u t a n o th e r e n d a n g e re d This a ffe cts th e air, th e water, and th e animal. W rite a sho rt land. Many plants th a t m anatees eat e xp la n a tio n o f w h y it have died. Manatees p re fe r w a rm water, is en dangered. b u t w a te r te m p e ra tu re s along th e coast m ay be cooling. .. -Journal R esearch and w rite a b o u t it o n lin e a t www.macmillanmh.cofn EXTEND Hath in Science butterfly Making a Hundredths Box Scientists are w o rk in g to p ro te c t m anatees and o th e r e n d a n g e re d animals. The U n ited States Fish and W ild life Service, o r USFWS, keeps a list o f species th a t are en d a n g e re d . The Karner blue b u tte rfly and San Francisco g a rte r snake ► A hundredths box can help you write percents. The word percent means “out of 100.” So 25 percent means 25 out of 100. To show 25 percent, shade in 25 of 100 boxes. are tw o examples. The ta b le b e lo w show s th e n u m b e r o f e n d a n g e re d anim al species t h ro u g h o u t o u r nation. Endangered Animal Species in the United States Animal Group Num ber of Endangered Species Percentage of Total ► A percent can also be written as a fraction. 25 percent = ^ = -J - mammals 68 17 birds 76 19 reptiles 14 3 am phibians 13 3 fishes 75 18 Use th e ta b le to solve these insects and spiders 59 14 m a th pro b le m s. o th e r invertebrates 105 26 Total 410 100 Solve It 1. W h a t p e rc e n ta g e o f e n d a n g e re d species are S o u rce : U S F W S T h re a te n e d a n d E n d a n g e re d S p e cie s S ystem , S e p t. 2 0 0 6 insects and spiders? 2. W h ic h v e rte b ra te g ro u p has th e high est p e rc e n ta g e o f e n d a n g e re d species? 3. V e rte b ra te s m ake up w h a t p e rc e n ta g e o f San Francisco garter snake e n d a n g e re d species? 97 EXTEN D Systems in Animals ostrich Look and Wonder Did you know that birds can run? Ostriches run the fastest— nearly 64 kilometers per hour (40 miles per hour)! They use their powerful leg muscles to escape danger quickly. W hat other body systems help animals survive? EN G AG E Explore How does an earthworm respond to light? Form a Hypothesis How will an earthw orm react to light? W rite a hypothesis. Test Your Hypothesis 10 Gently place an earthw orm on a moist paper towel. 0 Observe Use the hand lens to watch the earthw orm for several minutes. W hat does it do? Does the w orm stay in one place or does it move around? Record your observations. 0 Experiment Shine a flashlight on the earthw orm for about one minute. W atch how it reacts. Record your observations in a chart. 0 Repeat step 3 three more times. Record your observations. Draw Conclusions ( 0 Interpret Data Did your results sup port your hypothesis? W hat happens when an earthw orm is exposed to light? 0 How m ight an earthw orm sense light? Explore More Can an earthw orm sense light when under the ground? Form a hypothesis. Design an experiment to answer the question. M a te ria ls L Essential Question Animals have different organ systems. A system is a group of parts that work together. How do systems help animals survive? y Vocabulary skeletal system, p. The Skeletal and Muscular Systems 1 0 0 muscular system, p. nervous system, p. 1 0 0 1 01 respiratory system, p. 1 0 2 circulatory system, p. 103 excretory system, p. 103 digestive system, p. 104 Reading Skill O Cause and Effect Cause —► E ffe ct iiHt i p w p How do animals move and sense changes? — «rni*nin ~,ii •r r -w n r m n M e in i Bone is living tissue. A vertebrate’s bones make up its skeletal system (SKE»luh»tul S IS *tum ). This is the frame that supports an animal’s body. It also protects the organs inside. The skeletal system works with another system to allow vertebrates to move. This is the muscular ( M U S * k y u h * lu r ) system. It is made of strong tissues called muscles (M U H *s u lz ). To move, the muscles shorten and pull on the bones. How do invertebrates move? M ost have some kind of muscular system. Earthworms wriggle by shortening and stretching their muscles. y Technology e-Glossary, e-Review, and animations online at www.macmillanmh.com A frog uses its strong leg muscles to jump. As in many animais, the muscles work in pairs to move the skeleton. 100 EXPLAIN The Nervous System The master control system of the body is the nervous (NUR*vus) system. The nervous system is made of nerve cells. Invertebrates have simple nervous systems. A sponge, for example, has only a few scattered nerve cells. Vertebrates have complicated nervous systems. In vertebrates, millions of nerve cells work together as nerves. The nervous systems of vertebrates consist of a brain, spinal cord, nerves, and sense organs. These help animals use senses— such as sight, hearing, taste, touch, and smell— to detect changes in their surroundings. Owls have a keen sense of sight. Large eyes help them see at night. OQuick Check Cause and Effect How do the skeletal and muscular systems work together? Critical Thinking How is the nervous system important to the other body systems? The dolphin’s brain sends a message to jump. The message travels through the dolphin’s nerves to its muscles. Then the dolphin leaps into action! Quick Lab How do air and blood travel in the body? Make a Model Lung The Respiratory System O Your teacher will cut the b o ttom s o ff of a plastic bottle arid a balloon. Stretch the balloon over the b o tto m of the bottle. Tape it in place. ^ Put one end of a straw into the neck of a whole balloon. Wrap a rubber band around the neck and straw. Make a tig h t seal. 0 Insert the straw and balloon into the to p of the bottle. Fix them in place w ith modeling clay. The balloon should hang inside the bottle. o Make a Model Push and pull on the balloon that is stretched over the b o tto m of the bottle. W hat happens? © Infer The diaphragm (D l*uh*fram ) is a muscle that inflates the lungs. W hich part of your model represents the diaphragm? How does the model show how lungs work? EXPLAIN All animal cells need oxygen. To get oxygen from the air into their cells, most animals use a respiratory (R E S * p ru h * to r* e e ) system. The respiratory system brings oxygen to the blood and removes wastes, like carbon dioxide gas, from the blood. Some small invertebrates, like worms, do not need such a system. Gases move easily into and out of their tissues. Larger animals need a respiratory system. They use organs such as gills or lungs to exchange gases with the water or the air. Adult salamanders have lungs. Like all amphibians, they also breathe through their skin. Respiratory and C irculatory Systems to b o d y Read a D iagram "Vr r o m ooay body j Which organs do the fish and the hamster have in common? to gills Clue: Compare and contrast the tw o drawings. heart [^ ^ rjü fc S c /e n c e in Motion W a tc h re s p ira tio n a nd c irc u la tio n in a c tio n a t www.macmillanmh.com The Circulatory System The Excretory System The heart, blood, and blood vessels make up the circulatory (S U R * k y u h * lu h * to r* e e ) system. The job of the circulatory system is to move blood through the body. The blood carries oxygen, food, and water to the body’s cells. It also removes the cells’ wastes. When cells break down food and other chemicals, they produce wastes. The excretory (E K *s k ru h * to r*e e ) system removes these wastes. The heart is the main organ of the circulatory system. It has strong muscle tissue to pump lots of blood. The hearts of most fish have two parts, or chambers. An amphibian heart has three chambers. Mammals and birds have hearts with four chambers. Sponges and cnidarians do not have hearts. In fact, they have no circulatory system at all! B lood is a c tu a lly a liquid tissue. The liver, kidneys, bladder, skin, and lungs are excretory organs. The liver and kidneys filter wastes from the blood. The bladder stores liquid wastes. The skin sweats to remove excess minerals. Lungs remove waste gases from cells. So do gills. Quick Check Cause and Effect What would happen if blood did not pick up oxygen in the lungs? Critical Thinking What do the respiratory and circulatory systems have in common? 103 EXPLAIN How is food broken down? Animals take in food for energy. Until that food is broken down, body cells cannot use that energy. The digestive (di«JES«tiv) system helps break down food. In simple animals like sponges, cells along the body walls turn food into small particles. Other simple invertebrates have digestive systems with one opening. Food and wastes enter and exit through that opening. Segmented worms have digestive systems with two openings. Food enters through the mouth. Wastes exit through the tail end. Reptiles and amphibians have a more complex digestive system. Study the diagram below. How many digestive organs are shown? M ammals have a similar system. The stomach churns and mixes food. Digestive juices break it down. The food’s nutrients travel to the small intestine. There they are absorbed by the blood and carried to cells. The food’s wastes pass through the intestine and leave the body. j Quick Check Cause and Effect What happens to the food that a dog eats? Critical Thinking Predict what will happen to an animal that has a damaged digestive system. mouth stomach intestine Read a Diagram What is the path of food in the turtle’s digestive system? Clue: Follow the arrows. L. Lesson Review -À Think, Talk, and W rite Visual S u m m ary Animals use nervous, skeletal, and muscular systems to respond and move. The circulatory and respiratory systems transport blood and oxygen. The digestive system breaks down food for energy. The excretory system removes the food waste. 0 Vocabulary T h e ________ system takes in oxygen from air or water. ¡ 0 Cause and Effect How Cause -► E ffe ct does the nervous system cause the muscular and skeletal systems to move your arm? 0 Critical Thinking You clim b a flight of stairs and find th a t your heart starts beating faster and you take deeper breaths. W hy does physical activity affect you this way? 0 Test Prep The stomach is part of which body system? A dig e stive B nervous c skeletal M ak e a ia»]l»M ;iid S tu d y G u id e Make a three-tab book. Use it to summarize w hat you learned about animal systems. D c irc u la to ry Response ar\À m ovem ent 0 systemi Test Prep The excretory system A takes in oxygen. B s u p p o rts th e m u scular system, Oxygen c breaks d o w n food. transport systems Food a n d Warte D gets rid o f wastes. 0 Essential Question How do systems help animals survive? systems Writing Link W rite an Essay Which of the five senses is most im po rta nt to you? W rite an essay about how it helps you understand changes in your environment. A r t L ink Draw a Diagram Draw a diagram of an entire animal. Show the main organs of each body system. A ttach labels that name the organs and explain w ha t they do. “ R 0V i0W Summaries and quizzes online at www.macmillanmh.com 105 EVALUATE Be a Scientist Materials Structured Inquiry How do feet help birds move in water? Form a Hypothesis Birds travel in the air, on the land, and in the water. How does the shape of a b ird ’s feet help it to swim? W rite your answer in the form “ If a bird has feet th a t are ... , then it will move be tter in the water.” Test Your Hypothesis Make a Model Spread out three craft sticks in a fan shape. Glue the sticks in place. This is the frame for your bird foot. contact paper 0 Follow step 1 to make a second bird foot. 0 Cover the to p and b o tto m of the first bird fo o t w ith contact paper. Cut the paper to the correct size around the outside of the foot. Leave the second fo o t uncovered. Q Observe Drag each fo o t scissors basin of water 106 EXTEND through a basin of w ater several times slowly. Observe the am ount of water that gets pushed aside each time. Record your observations. Draw Conclusions 0 Interpret Data W hich fo o t Pekin duck moved more water? W hich fo o t is be tter suited for swimming? 0 Infer W hat kind o f feet do your models represent in real life? Guided Inquiry How do teeth help animals eat? Form a Hypothesis Many animals have fro n t teeth that are shaped differently from their back teeth. How does the shape of their teeth help animals eat different foods? W rite a hypothesis. Open Inquiry W hat other questions do you have about animal structures? Design an investigation to answer one of your questions. W rite the steps so that another group can do the experiment by follow ing your procedure. Test Your Hypothesis Make a plan to test how different shapes of teeth are used for eating different kinds of foods. Choose foods that animals m ight eat, such as carrots, corn, meat, or seeds. W rite the steps you will follow. Then con duct your experiment. Record your results and observations. Draw Conclusions W hat can you conclude about the different shapes of teeth? W hich ones are better for eating which kinds of foods? Why? 107 EXTEND I Cycles ca terp illa r of a sw allow tail b u tte rfly Look and Wonder When this caterpillar is ready, it will spin a cocoon. There it will live for a short time. The next time it appears, it will have wings! How does a caterpillar change to a butterfly? ENGAGE Inquiry A ctivity How does a caterpillar change as it grows? Materials Purpose Explore how a caterpillar changes into a butterfly. Procedure O Your teacher will give you a caterpillar. Place it gently inside the b u tte rfly kit. Put the food and w ater in the proper place inside the kit. 0 Observe Look carefully at your caterpillar butterfly kit each day. Record any changes in a table like the one shown. J Draw Conclusions O Interpret Data How many different forms did your caterpillar take? Describe each form. Q How does the final stage o f a caterpillar’s life compare w ith the first stage? 0 Predict Do all caterpillars go through these same life stages? Design an investigation that you could test. Explore More Do other animals have different stages of development? How could you find out? .à O b s e r v a ti o n s B o d y C h a n g e sB e h a v i o r C h a n g e s D a y 1 2 3 4 EXPLORE What are the stages of an animal’s life? How do animals grow and reproduce? ► Vocabulary life cycle, p. 1 1 0 life span, p. ill metamorphosis, p. The caterpillar goes through many changes as it grows into a butterfly. These stages of growth and change make up an organism’s life cycle. All living things follow a pattern of birth, growth, reproduction, and death. 112 clone, p. 114 heredity, p. 114 inherited behavior, p. 116 instinct, p. 116 learned behavior, p. 116 ► Reading Skill © Sequence F irst N ext Each different organism has its own kind of life cycle. A moth begins A penguin, for example, life as an egg. changes slowly as it grows. The chick hatches from its egg after many weeks. It depends on its parents for warmth, shelter, and food. Soon the chick grows a thick coat of downy feathers. This helps it stay warm and dry by itself. As the penguin gets older, waterproof feathers grow in place of the down. They keep the adult dry while it swims in search of food. Technology e-Glossary and e-Review online at www.macmillanmh.com penguin egg 110 EXPLAIN newly hatched chick young penguin Life Spans An organism’s life span is how long it can usually live in the wild. A moth has a life span of about one week. The oldest recorded age for a human is 122 years! Scientists do not know why some animals have longer life spans than others. yQuick Check Sequence What are the main stages of an animal’s life? a boa constrictor can live as long as 20 years. Critical Thinking The average life span of a mouse is three gears. Why don’t all mice live for three years? The life span of a skunk is about three years. Koi fish can live to be 100 years old! penguin EXPLAIN What is metamorphosis? M ost young animals look like smaller copies of their parents. Kittens look like small cats. Chicks look like small birds. Other young animals don’t look like their parents at all. Take insects, for example. Butterflies and most other insects go through metamorphosis (me*tuh*MOR*fuh*sis). The process of m etam o rp hosis has several separate growth stages. Incomplete Metamorphosis Damselflies are insects that go through incom plete m etam orphosis. In this kind of metamorphosis, the difference in growth stages is hard to see. As the insect grows and changes, it molts. M olting is when an animal gets too large for its exoskeleton. It sheds the exoskeleton and grows a new one. Other insects that go through incomplete metamorphosis are grasshoppers and termites. Incom plete M etam orphosis 0 The nymph leaves the water. It sheds its skin and grows small wings Q Q A young damselfly, or nymph (NIM F), hatches from an egg. A female ^¥g damselfly I lays eggs on the stem of a water plant. The nymph molts several times. Then it becomes an adult. C om plete M etam orphosis ^ Larva (T) A female b u tte rfly lays eggs on a leaf. (2) A w orm like larva hatches from the egg. It begins to eat the leaf. Adult (3) The larva becomes a p u p a (PYEW *puh) and develops adult tissues and organs. Read a Photo (4) The adult animal is a butterfly. It has six legs, two pairs of wings, and a pair of long antennae. Butterflies can reproduce. J After which stage does a caterpillar become a butterfly? Clue: Follow the numbered captions. Complete Metamorphosis Butterflies go through com plete m etam orphosis. Look at the sequence of photos. Each growth stage looks different. Beetles, flies, and mealworms also go through complete metamorphosis. ) Quick Check Sequence What are the stages in the complete metamorphosis of a butterfly? Critical Thinking What stages of life do humans seem to go through? List some of them. 113 EXPLAIN How do animals reproduce? The life cycle of every animal includes reproduction. This is when parent animals make offspring. One Parent Cnidarians and other simple invertebrates reproduce by budding. A bud forms on the adult’s body. The bud slowly develops into a new animal. After some time, the bud breaks off. It grows into an adult. Sea stars and other echinoderms can reproduce by regeneration (rih *je *n u h *R A Y *s h u n ). This is when a whole animal develops from just a part of the original animal. Both budding and regeneration produce clones. A clone is an exact copy of its parent. Birds need tw o parents to produce eggs. One parent may guard the eggs while the other parent gets food. Inheriting Traits A clone has characteristics, or traits, that are identical to those of its parent. When traits are passed from parent to offspring, we say those traits are inherited ( in * H E R * u h * tid ). All animals inherit traits from their parent or parents. The passing of these traits is called heredity (h u h * R E H * d u h * te e ). Kinds o f R e p ro d u c tio n ^ budding regeneration fertilization Read a Table Two Parents Another kind of reproduction requires cells from two parents. The female cell is called an egg. The male cell is a sperm. When an egg and a sperm join, offspring are produced. This joining is called fertilization (fur*tuh»luh»ZA Y »shun). As the fertilized egg grows, it is called an em bryo (E M * b re e * o h ). An embryo has traits from both its parents. It is not identical to either parent. Which animal reproduces with two parents? Clue: Look at the data in the last column. JQuick Check Sequence Describe the steps that take place in the formation of an embryo. Critical Thinking Can offspring from two parents be clones? Explain. 115 EXPLAIN What is inherited? Animal Cards O Make tw o sets of inherited traits. Use yellow cards for female parents and orange cards for male parents. 0 W rite an example of a trait on each yellow card. On each orange card, w rite different examples of the same traits. 0 Use Numbers Choose one card from each set. How many com binations of different traits can you make? O Infer How do the cards model reproduction w ith tw o parents? Look at the pigs in the photograph below. Some of their traits, such as color, are determined by heredity. But how are the pigs acting, or behaving ? Is behavior an inherited trait? Perhaps. An inherited behavior is a set of actions that parents pass on to their offspring. The simplest kind is a reflex, like blinking. A less simple example is instinct. Instinct is a way of acting that an animal does not have to learn. Birds build nests, and spiders spin webs, by instinct. N ot all behaviors are inherited. Some are learned. Learning can happen when an animal interacts with its environment or with others. A learned behavior occurs when an animal changes its behavior through experience. Do you ride a bicycle? Bicycling is a learned behavior. V)QuickCheck Sequence Describe how you could teach a learned behavior. Critical Thinking What are other examples of learned behavior? L. Lesson Review U Think, Talk, and W rite Visual S u m m ary The life cycle of an animal includes birth, grow th, reproduction, and death. 0 Vocabulary _______ takes place when a sperm and an egg combine. 0 Sequence Describe w hat happens during the incom plete metamorphosis o f a damselfly. There are tw o kinds of m etam orphosiscom plete and incomplete. Animals reproduce when parents make offspring. Offspring w ith tw o parents inherit traits from both. 0 Critical Thinking W hy are some behaviors, such as eating, inherited instead of learned? O Test Prep Which animal’s metamorphosis has a pupa stage? M ake a S tu d y G u id e Make a trifold book. Use it to summarize what you learned about animal life cycles. Mam Xded What X l e a r n e d ... a fro g b d a m se lfly c b u tte r fly S k e tc h e s D g ra ss h o p p e r Life cycle 0 MetomorpHosiS Essential Question How do animals g row and reproduce? Trd'i+S W ritin g L ink Fictional Narrative Choose an animal that goes through complete metamorphosis. Write a story from the point of view of that animal. Include all the stages of the animal’s metamorphosis. Solve a Problem One minute after fertilization, an egg splits. It becomes tw o cells. The cells continue to split every minute. How long will it take until there are 64 cells? ~ R e V ÌB W S u m m a rie s and q u iz z e s o n lin e a t www.macmillanmh.com 117 EVALUATE Reading in Science C h r i The island o f M adagascar lies o ff the southeast coast o f Africa. This island has plants and animals fo u n d now here else in the w orld . Chris R a x w o rth y is a scientist at the A m e rica n Museum o f Natural History. He has spe nt m any years g a th e rin g in fo rm a tio n a b o u t these animals and th e ir habitats. On the island, you can find unusual creatures like the Mantella poison frog. This tin y fr o g ’s viv id colors w arn preda tors to stay away. Female frogs lay 2 0 - 3 0 eggs on land in a clum p. The eggs are hidden in m oist areas near streams. W hen it rains, ta d p o le s hatch. They w rig g le th e ir w ay into th e stream. In a b o u t a year, th e ta d p o le s tu rn into adults. urope Africa equator EXTEND ft Adult Mantella poison frogs are only about one inch long ■.• « I ' M eet a Scientist The d w a r f de ad leaf cha m ele on also makes its h o m e on Madagascar. This unusual anim al ge ts its name because it looks ju s t like a dead leaf. D uring th e day, th e cha m ele ons hide o u t a m o n g th e dead leaves o f the rain fo re st floor. A t night, th e y clim b up in to th e low branches to sleep. Female cha m ele ons lay 2 o r 3 large eg gs in th e leaves on th e forest floor. Baby cha m ele ons ha tch a b o u t ten w eeks later. In 9 to 12 m onths, the y are all g ro w n up. The tro p ic a l c lim a te o f M adagascar is h o m e to lots o f living things. B ut th e ir h a b ita ts are in tro uble . Forests are being c u t d o w n fo r fa rm la n d and c a ttle grazing. As th e forests disappear, so d o the animals th a t live there. Chris and o th e r scientists w a n t to make sure th a t creatures like th e Mantella poison fro g and d w a rf dead leaf cha m e le o n d o n ’t d is a p p e a r forever. Waterfalls are common in the rain forests of Madagascar. . ■■■■■■■■■■■■■■I Í1T0 f«¿ ■T01 -pi . i -.yX f f ï i i I- -T- ‘ » Compare and Contrast f W rite About It Compare and Contrast H ow does the life cycle o f th e Mantella poison fro g co m p a re to th e life cycle o f the ► To compare, use words such as like and both. ► To contrast, use words such as unlike and but. d w a rf dead leaf cham eleon? C o n n e c t to ^ -J o u rn a l R esearch and w rite a b o u t It o n lin e a t w w w .m acm illanm h.com A m e r ic a n M u seum s N a tu r a l H is t o r y at www.ma .com; EXTEND Fill each blank with the best term from the list. Visual S u m m ary Lesson 1 Invertebrates bird, p. 93 invertebrates, p. 79 are animals w ith o u t backbones. digestive system, metamorphosis, p. 104 p. 112 exoskeleton, p. 82 nervous system, p. 101 Lesson 2 Vertebrates heredity, p. 114 reptile, p. 92 are animals with backbones. instinct, p. 116 vertebrate, p. 9 0 1. More than 95 out of every 100 animals a r e ________ Lesson 3 Animals have body systems that help them carry out basic life functions. 2. Food is broken dow n by the 3. A (n) is any animal that has a backbone. Lesson 4 Animals go through stages o f grow th and change during their life cycles. 4. A rth ro p o d s have a h a r d __ th a t protects their bodies. 5. A (n) is w a rm -blo ode d and has feathers. 6 . Butterflies go throug h a process of change c a lle d ________ M ake a L illie S tu d y G u id e 7. The brain and sense organs are part Tape your lesson study guides to a piece of paper as shown. Use your study guide to review w hat you have learned in this chapter. 8 . A lizard is a cold -bloo ded vertebrate belonging to the class. of an anim al’s ________ Refponie In ve rte brate s A n im a ls w ith Arthropods Backbones V ertebrates "lovenjenttysternr I fr°o**yi? 9*o*rt ] *>*♦*.»* 9. Traits are passed from parent to offspring t h r o u g h ________ 10. A ( n ) _______ is a behavior th a t an animal does not have to learn. nommais VVormS 120 f t r j a - Glossary Words and definitions online at www.macmillanmh.com Skills and C o n c e p ts .. ______________ (DOK 2-3 j Answer each of the following. 11. Main Idea and Details W hat is the purpose of the circulatory system? Provide details to sup port your answer. 12. Classify Choose an animal discussed in the chapter. Classify it using w hat you have learned—as vertebrate or invertebrate, w a rm -blo ode d or c o ld blooded, and so on. Explain each answer. 19. W hich bo d y system carries messages to the oth er bo d y systems? A excretory system B nervous system C respiratory system D muscular system 20. How are animals different from one another? 13. Critical Thinking How m ight a fish control its body temperature? 14. Explanatory W riting How are echinoderms and arthropods alike? How are they different? Provide examples of each. P e rfo rm a n c e A ssessm ent Make an Invertebrate Reference Book Make a picture book showing the invertebrates in this chapter. 15. Classify W hich class of vertebrates has cold -bloo ded organisms that lay eggs on land? 16. Classify W hich classes of vertebrates have organisms that most likely care for their young? 17. True or False Dam selflies go through com plete m etam orphosis. Is this statem ent true or false? Explain. 18. True or False A ll fish have bones. Is 1. W rite the name of each invertebrate you studied. 2. List the invertebrates in alphabetical order in your book. Draw a picture of the animal next to its name. 3. W rite dow n all the inform ation you have learned ab out the animal. 4. W rite a paragraph th a t explains how tw o animals from your book are similar and different. this statement true or false? Explain. s -R e v ie w S u m m a rie s a n d q u iz z e s o n lin e a t www.macmillanmh.com 121 Test Preparation Q Which animal is classified as an invertebrate? — 0 The picture below shows a hydra reproducing. A o c to p u s B chicken The hydra’s offspring will most likely have A none o f the p a re n t’s traits. B som e o f th e p a re n t’s traits. C half o f th e p a re n t’s traits. D all o f th e p a re n t’s traits. C deer DOK 2 E l In animals, which system is responsible for communication within the body? A re s p ira to ry system B d ig e s tiv e system C skeletal system D nervous system D eagle DOK 2 □ DOK I 121A Which animal most likely cares for its young? A b ird C insect B fro g D snake DOK I ____________________________________ — 0 Which shows complete metamorphosis? n The pictures below show a fish and a rabbit. Z' rabbit Name two body structures the fish has that the rabbit does not have. DOK I Tell how each structure helps the fish survive in its environment. DOK 2 Iheck Your Understanding Question Review Question Review 1 pp. 78-81 4 pp. 92-93,110-114 2 pp. 114-115 5 pp. 112-113 3 pp. 100-104, R20-R21 6 pp. 90-94,102-103 121B Zoologist Do you love animals? If so, you might like to be a zoologist (zoh»A H «luh*jist). Zoologists are animal scientists. They study all kinds of animals. Some zoologists work in laboratories. Others study animals in their natural habitats. Still others work in museums or zoos. All zoologists have college degrees. M ost have more than one degree. If this career sounds appealing, start exploring it! Ask your parent or guardian to take you to a local zoo, aquarium, or animal shelter. You A Zoologists study animals in their natural habitats, might even meet a zoologist there. Bird Handler What do eagles, hawks, and owls have in common? They are all birds of prey. Birds of prey have good vision for catching prey. They also have very strong claws! People who care for these birds in wildlife centers are trained bird handlers. Some bird handlers show the animals to visitors. Others collect birds from the wild. To be a bird handler, you need training. ’J ° You have to catch the birds without harming them. You need to feed them and keep them healthy. Bird handlers know how to be safe around these majestic birds! 122 . T . ... for hawks and other birds ▲ Trained bird handlers care ™ ¿ .© - C a r e e r s at www.macmillanmh.com