How Can We Classify Invertebrates?

SC.3.L.15.1 Classify animals into major groups (mammals, birds, reptiles, amphibians, fish, arthropods, vertebrates and invertebrates, those having live births and those which lay eggs) LESSON according to their physical characteristics and behaviors. SC.3.N.3.2 Recognize that scientists use models to 3 help understand and explain how things work. HowESSENTIAL QUESTION Can We Classify Invertebrates?

Engage Your Brain

Find the answer to the following question in this lesson and record it here. Look at this “furry lobster.” How do you know it is not a mammal?

ACTIVE READING Main Idea and Details Detail sentences give information Lesson Vocabulary about a topic. The information may be List each term. As you learn about each examples, features, characteristics, or one, make notes in the Interactive Glossary. facts. Active readers stay focused on the topic when they ask, What fact or information does this sentence add to the topic? (l) ©Image Source/Getty Images; (r) ©Gary Bell/Corbis (l) ©Image Source/Getty

311 © Houghton Mifflin Harcourt Harcourt © Houghton Mifflin Publishing Company 312 ocean water. each oftheirarmsinto stars release tinyeggsfrom Most kindsoffemalesea the oceantoyourownbackyard. Invertebrates liveinmanyplaces,from worms, andinsectsaresomekinds. invertebrates. Jellyfish,crabs,spiders, backbones. Therearemanykindsof ACTIVE invertebrates. and worm alike? They are all How are anoctopus,lobster, cricket, No Bones! vocabulary eachtimeitisused. two pages,findandunderlinelesson Invertebrates READING areanimalswithout Asyoureadthese soft body. shell toprotect its The snailhasahard or hard outercovering. A wormhasnobackbone has lotsoflegs! This centipede

© Houghton Mifflin Harcourt (starfish) ©Andrew J. Martinez/Photo Researchers, Inc.; (centipede) ©Scott Camazine/Photo Publishing Company Researchers, Inc.; (snail) ©Artville/Getty Images; (tr) ©Carl Pendle/Photographer’s Choice/Getty Images © Houghton Mifflin Harcourt (girl) ©Tim Hall/Getty Images; (jellyfish) ©Melba Photo Agency/Alamy Images; (crab) (dragonfly) ©Rod Planck/Photo Researchers, Inc.; (hippo) ©Franz Aberham/Stock Image/Getty Publishing Company ©Photodisc/Getty Images; (giraffe) ©Digital Vision/Getty Images; Images; (bug) ©Ted Kinsman/Photo Researchers, Inc.

Place anXbeneaththepictures ofinvertebrates. of leaves. on theundersides Ladybugs laytinyeggs 313 314 head hastwoantennae.Anditsixlegs. An insect’s bodyhasthreemainsegments.Its How canyoutellwhicharthropodsareinsects? covering thatprotectsthem. parts, andtheyhaveahard,outer legs. Theirbodiesaredividedintosegments,or ACTIVE them special? animal.What makesany othertypeof arthropodsThere than are more typesof Arthropods pages, findandunderlinefactsaboutinsects. Insects Arthropods READING arethelargestgroupofarthropods. areinvertebrateswithjointed scorpion Asyoureadthesetwo walking stick butterfly

© Houghton Mifflin Harcourt Publishing Company © Houghton Mifflin Harcourt (paper) ©Photodisc/Getty Images Publishing Company have different numbersoflegs. But otherkindsofarthropods parts. Insectsalwayshavesixlegs. arthropods onlyhavetwobody not insects.Unlikeinsects,these are arthropods,too.Yet theyare Spiders, scorpions,andcrabs tick net OtherArthropods Insects arthropods shownonthesepages.

Fill in the chart with the names of Fill inthechartwithnamesof Arthropods the listasyoufindit. arthropods. Cross eachoff

beetle tick ant spider walking stick butterfly scorpion Find andcircle these beetle 315 316 All theOthers! Snails, ACTIVE invertebrates? Lookandfindout! invertebrates. What otheranimalsare Arthropods aren’t theonlykind of draw circlesaroundthenamesofinvertebrates. READING and inpools neartheshore. Brittle starslivein theocean in betweenrocks. bones, itcanfititsbody Since asquidhasno Asyoureadthesetwopages,

Squids, are saltwatersnails. [ Periwinkles PER • ih • wing •

kuhlz] and

© Houghton Mifflin Harcourt (brittle star) ©Andrew J. Martinez/Photo Researchers, Inc.; Publishing Company (periwinkle) ©Premaphotos/Alamy; (squid) ©Novastock/Photo Researchers, Inc. DO THE MATH Use Subtraction Facts

If 485 of every 500 animals are invertebrates, how many are vertebrates?

Like many invertebrates, sea slugs lay eggs. When this octopus hatched from its egg, it was about the size of a housefly.

Anemones [uh•NEM•uh•neez] attach themselves to rocks or other surfaces.

A clam has a soft body with a hard shell to protect it. (anemome) ©Corbis; (octopus) ©Jeff Rotman/Photo Researchers, Inc.; Rotman/Photo Researchers, (anemome) ©Corbis; (octopus) ©Jeff Inc. J. Martinez/Photo Researchers, (slug) ©Photodisc/Getty Images; (clam) ©Andrew

317 © Houghton Mifflin Harcourt Harcourt © Houghton Mifflin Publishing Company Sum It Up

The blue part of each summary statement is incorrect. Write words to replace the blue parts.

1 Invertebrates are 2 All invertebrates are animals with backbones. arthropods. Researchers, Inc. Researchers, 3 4 Arthropods have one Insects have eight legs, body part and jointed legs. two body parts, and antennae.

6 Snakes and lizards are 5 Most invertebrates invertebrates that are not give live birth to young. arthropods. (bl) ©blickwinkel/Alamy; (cl) ©Ingram/Getty Images; (tl) ©Andrew J. Martinez/Photo Researchers, Inc.; J. Martinez/Photo Researchers, (bl) ©blickwinkel/Alamy; (cl) ©Ingram/Getty Images; (tl) ©Andrew Kinsman/Photo (br) ©Photodisc/Getty Images; (cr) ©Peter Arnold/Digital Vision/Getty Images; (tr) ©Ted

318 © Houghton Mifflin Harcourt Harcourt © Houghton Mifflin Publishing Company Brain Check LESSON 3

Name Vocabulary Review

1 Use the clues to fill in the missing letters of the words. 1. v the classification of an animal without a backbone

2. i t an arthropod with six legs, three body parts, and antennae

3. t r an animal with jointed legs, a segmented body, and a hard outer covering

4. s Most vertebrates lay ___.

5. o d the kind of legs all arthropods have

6. c v g All arthropods have a hard, outer _____.

7. t s an ocean animal with eight legs that is not an arthropod

2 Look at the drawing of the scorpion. Complete the chart.

How many legs does it have?

Does it have antennae?

Does it have segmented body parts?

Is it an arthropod?

Is it an insect?

3 Draw an arthropod of your choice. Write what makes it an arthropod.

Make a poster to show different invertebrates. Take It Group them as arthropods or not arthropods. Use labels to show the differences between the two Home groups.