E-BOOK SAMPLE. Skeletons. (Selected Pages) Meish Goldish

(S Meish Goldish K O O LE s) B P age E- M ed P SAelect Skeletons Science Objectives • Identifies the functions of various structures of living t...
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Meish Goldish

K O O LE s) B P age E- M ed P SAelect

Skeletons

Science Objectives • Identifies the functions of various structures of living things. • Knows that the human body has different systems for different functions and that these systems interact with one another. • Identifies physical characteristics of a category of organisms. • Next Generation Science Standards: 1-LS1-1, 2-LS4-1

Skeletons ISBN: 978-1-4007-3663-8 Program Author: Dr. Brenda Parkes Newbridge Educational Publishing 33 Boston Post Road West, Suite 440, Marlborough, MA 01752 www.newbridgeonline.com Copyright © 2016, 2003 Sundance/Newbridge, LLC All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage or retrieval system, without permission in writing from the publisher. Cover Photograph: X-ray of a long-eared bat Table of Contents Photograph: Students studying skeletons Photo Credits Cover: Dave Roberts/Photo Researchers, Inc.; Page 5: (left) Digital Vision, (bottom left) E. R. Degginger/Photo Researchers; Page 6: (top) Bettmann/Corbis; Page 7: (bottom) Courtesy Hospital for Special Surgery; Page 11: Eyewire; Page 12: (right) Warren Jacobi/ Corbis; Page 13: (right) Daniel J. Lyons/Bruce Coleman, Inc.; Page 14: (left) Robert Pearcy/Animals Animals, (right) Dave Roberts/Photo Researchers; Page 21: AP Photo/The Daily News/Bill Wagner; Page 22: Michael S. Yamashita/Corbis. Illustrations by Tom Leonard, Pages 9, 10, 16

Skeletons Meish Goldish

Contents An Inside Look . . . . . . . . . . . . . . . . . 4 Animals with Backbones . . . . . . . . 10 Animals with No Backbones . . . . . 18 Glossary . . . . . . . . . . . . . . . . . . . . . 23 Index . . . . . . . . . . . . . . . . . . . . . . . . 24

An Inside Look

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magine that you have X-ray vision. If you look at any animal, you can see inside it. What you see will depend on the kind of animal you are looking at. If you look inside a mouse, a snake, a person, or many other animals, you will see a skeleton. Some other animals wear their skeletons on the outside, and some have no skeleton at all. Get set for an amazing inside look!

The skull is an important part of a skeleton. This is an X-ray of a skull. 4

Pigeon

Iguana

Dog Human

5

Animals with Backbones

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ne of the most important parts of your skeleton is your backbone, which is also called your spine. Your backbone supports your body and protects your delicate spinal cord.Your spinal cord carries messages from your brain to all the other parts of your body. Your brain might send a message to your arm to throw a ball, or to your legs when you want to run. Without your backbone and spinal cord, you would not be able to stand, sit, or move. Your backbone is not just one bone. It is made up of 33 small bones, called vertebrae. Animals with backbones are called vertebrates. All mammals, including humans, are vertebrates. So are birds, amphibians, reptiles, and fish.

All mammals have seven neck bones in their spine. Why do you think a giraffe’s neck is so much longer than yours? 10

Human Skeleton The words in italics are the names scientists use for the bones in the human skeleton.

skull cranium

ribs

arm bone humerus spine bones vertebrae

hip bone pelvis

thighbone femur

kneecap patella

forearm bones radius and ulna

hand bones metacarpals

finger bones phalanges calf bone fibula shinbone tibia

toe bones phalanges

foot bones metatarsals

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Slither, Leap, Swim Animals that move in different ways have different kinds of skeletons. A snake is a vertebrate that moves by curving its body from side to side. This movement pushes the snake forward. It can also coil up. A snake has no arms, legs, shoulders, or hips. Its whole skeleton is a skull, backbone, ribs, and tail. A snake uses its many ribs as well as its backbone when it slithers along the ground. Why can’t you coil up like this python? The joints in your backbone aren’t as flexible, and your arms and legs would get in the way. tail skull

ribs

vertebrae

Large snakes like this python can have more than 400 vertebrae. 12

vertebrae thighbone femur calf bone tibiofibula foot bones tarsals metatarsals toe bones phalanges

A leopard frog can leap more than 24 times the length of its body!

You have two bones in your lower leg, but a frog has just one strong bone.

A frog’s skeleton is good for jumping. A frog can leap very far because its back legs are so much longer than its short backbone. Imagine how far you could jump if your legs were twice as long as your back! When a frog gets ready to jump, it bends its hip, knee, and ankle joints very tightly. Then the long, powerful muscles attached to its hip, leg, and foot bones straighten the joints all at once and thrust the frog into the air. Its short front legs help it balance and act as shock absorbers when it lands. 13

Animals with No Backbones

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any animals you know about are vertebrates. That is, they have backbones. However, most animal species have no backbones. Animals without backbones are called invertebrates. Ninety-seven percent of Earth’s animal species are invertebrates.

Inside Out Actually, invertebrates have no bones at all, but many of them do have skeletons. This group of animals includes insects, spiders, crabs, and lobsters.

Crabs and spiders, like insects, have jointed legs. 18

Your skeleton, like that of all vertebrates, is on the inside of your body. An insect’s or a crab’s skeleton is on the outside of its body. It’s called an exoskeleton. Like a vertebrate’s skeleton, an exoskeleton supports an animal’s body and protects its organs.Your muscles are attached to the outside of your skeleton, but muscles are attached to the inside of an exoskeleton. An insect’s exoskeleton is made of a tough material called chitin. Unlike bone, an exoskeleton doesn’t grow. From time to time as an insect grows, it molts. It grows a larger exoskeleton and pushes off the old one. This cicada has just molted. It will leave its old exoskeleton on the twig. 19

Skeleton Clues On land, animals must have bones to support a big body. We know about the biggest land animals that ever lived—dinosaurs like Tyrannosaurus rex—because people have found the fossils of their skeletons. By studying an animal’s skeleton, scientists can figure out what the animal probably looked like and how it moved. They can see how the bones fit together and where the muscles were attached. Even millions of years after an animal lived, its skeleton can still tell an exciting tale.

From studying where muscles were once attached to bones, scientists know that Tyrannosaurus rex had extremely powerful jaws. 22

Glossary cartilage: a stiff, rubbery tissue that is found at the ends of bones, in some other parts of the body, and in place of bones in some kinds of fish chitin: the hard material that exoskeletons are made of exoskeleton: a hard supporting structure on the outside of an animal’s body. Animals such as insects, spiders, and crabs have exoskeletons. fossil: the hardened remains or trace of an animal or plant that lived long ago fused: joined in one piece, as if melted together invertebrate: an animal without a backbone joint: a place where two bones are connected ligament: a strong tissue that connects bones in joints marrow: the material inside bones in which new blood cells are formed mineral: a natural substance that does not come from living things molt: shed an outer covering, such as an exoskeleton. The old covering is replaced by a new one. skeleton: the framework that supports and protects the body of an animal species: a particular kind or type of living thing vertebra: one of the separate bones that make up a backbone.Vertebrae means more than one vertebra. vertebrate: an animal with a backbone

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Index amphibians 10 backbones 10, 12, 14, 18 bald eagle 17 birds 10, 16–17 blood cells 7 blood vessels 7 bones 6–7, 8, 9, 10, 11, 13, 15, 16–17, 18, 21, 22 brain 10 cartilage 15 chitin 19 crabs 18 dinosaurs 22 earthworms 20 exoskeleton 19 fins 14 fish 10, 14–15 fossils 22 frog 13 giant squid 21 heart 8, 17 human 5, 6, 10, 11 insects 18–19 invertebrates 18–21 24

jellyfish 20–21 joint 9, 12, 13, 15, 20 ligaments 9 lobsters 18 lungs 8 marrow 7 mineral 7 molting 19 muscles 8, 9, 13, 17, 19, 20, 22 nerves 7 reptiles 10 ribs 11, 12 sharks 15 skull 4, 11, 12 slugs 20 snake 12 species 18 spiders 18 spinal cord 10 spine 10, 11 Tyrannosaurus rex 22 vertebrae 10, 11, 12, 13, 14 vertebrates 10–17, 18, 19 X-ray 4, 7, 14

Think About Science 1. How is a backbone helpful to people and other vertebrates? 2. Look at the diagram on page 16. How are your arm bones and the bones in a bird wing alike and different? 3. What are some of the ways invertebrates are different from vertebrates?

Life Science • Structure and Function • Biodiversity and Humans

How is your skeleton like a giraffe’s? How do a bird’s bones help it fly? What kind of skeleton does a spider have? Take a look inside at skeletons—even some that aren’t on the inside at all!

Genre Subject/Strand Key Words Vocabulary

Informational Text, Nonfiction Science/Life Science vertebrates, invertebrates, exoskeleton, bones imagine, hind, particular, delicate, coil

Level GRL O Lexile 840L

ISBN 978-1-4007-3663-8

9 781400 736638 828447