MHE_Rdg_Wonders_LvRdr_G5_Approach_U6W3_28.pdf

Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:50PAIREDREADWhy Bat Flies at Nightby Jocelyn CranefieldExpository Text CV_CR14_LR_G5_U6W3L50_A_119233.indd 3CV_CR14_LR_G5_U6W3L50_A_119233.indd 314/03/12 11:17 AM14/03/12 11:17 AMSTRATEGIES&SKILLSComprehensionStrategy:Ask and Answer QuestionsSkill:Cause and EffectVocabulary StrategyParagraph CluesVocabulary adaptations,agile,caches,dormant,forage,frigid,hibernate,insulateContent StandardsScienceLife Science Photography Credit:Mark Moffett/Minden Pictures/Getty images.*The total word count is based on words in the running text and headings only.Numerals and words in captions,labels,diagrams,charts,and sidebars are not included.Word Count:1,432*AProgram:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:50Copyright The McGraw-Hill Companies,Inc.All rights reserved.No part of this publication may be reproduced or distributed in any form or by any means,or stored in a database or retrieval system,without the prior written consent of The McGraw-Hill Companies,Inc.,including,but not limited to,network storage or transmission,or broadcast for distance learning.Send all inquiries to:McGraw-Hill EducationTwo Penn PlazaNew York,New York 10121ISBN:978-0-02-119233-5MHID:0-02-119233-2Printed in the United States.1 2 3 4 5 6 7 8 9 DOC 15 14 13 12 11 10IFCIBC_CR14_LR_G5_U6W3L50_A_119233.indd 2IFCIBC_CR14_LR_G5_U6W3L50_A_119233.indd 214/03/12 11:17 AM14/03/12 11:17 AMPAIREDREADby Jocelyn CranefieldIntroduction .2Chapter 1From the Entrance to the Twilight Zone .4Chapter 2Dark and Surprising Places .10Conclusion.16Respond to Reading.18Why Bat Flies at Night .19Glossary.22Index.23Focus on Science .24 Essential QuestionHow are living things adapted to their environment?Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:50001-009_CR14_LR_G5_U6W3L50_A_119233.indd 1001-009_CR14_LR_G5_U6W3L50_A_119233.indd 115/03/12 11:43 AM15/03/12 11:43 AMIntroductionCaves are found all over the world.They often go a long way in from the entrance and go deep below Earths surface.At first a cave might seem to be just a dark,empty space.If you shine your flashlight inside the cave,you probably wont see anything.But if you go inside,you probably wont be alone.Caves can be on the coast,in a forest,or under a desert.They can be made out of limestone,marble,or lava.Some caves have beautiful stone formations,and others are full of smelly,poisonous gases.However,every cave in the world provides a home for animals.Lechuguilla Cave in New Mexico is famous for its beautiful mineral formations.2Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:502MICHAEL NICHOLS/National Geographic Stock001-009_CR14_LR_G5_U6W3L50_A_119233.indd 2001-009_CR14_LR_G5_U6W3L50_A_119233.indd 215/03/12 11:43 AM15/03/12 11:43 AMCAVE DEPTHKrubera Cave,7,188 feet deepBUILDING HEIGHT1,000 ft1,000 ft2,000 ft2,723 ft0 ft2,000 ft3,000 ft4,000 ft5,000 ft6,000 ft7,000 ftSome animals only visit caves and dont live there.Other animals live in caves all the time.Many of these creatures have adaptations to help them live in a cave.Adaptations are special features that help a living thing survive in a particular place.The Krubera Cave CAVES OF ALL SIZES More than 50,000 natural caves have been found in the world.Some caves are single tunnels,but others are huge systems of caves that connect with each other.The deepest cave we know of is the Krubera Cave,near the Black Sea.It is at least 7,188 feet deep.Compare its depth with the heights of some tall buildings,below.The longest cave is Mammoth Cave in Kentucky.It runs for more than 350 miles underground.CAVE LOCATIONS3Program:CR 14Component:LRG5U6W3 APDfVendor:Learning MediaLevel:503001-009_CR14_LR_G5_U6W3L50_A_119233.indd 3001-009_CR14_LR_G5_U6W3L50_A_119233.indd 315/03/12 11:43 AM15/03/12 11:43 AMSome animals visit caves to shelter or to sleep.They stay near the cave entrance.These animals are called trogloxenes,or cave visitors.Bats,skunks,raccoons,and snakes are trogloxenes.They spend part of their lives in caves,but they need to go outside to get their food.The Mexican free-tailed bat is a trogloxene.It is nocturnal.During the day,it roosts in colonies that hang from cave roofs.At dusk it flies out of the cave to catch insects.As the sun sets,these bats come out of their cave to hunt.From the Entrance to the Twilight ZoneChapter ONE 4Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:504Fred Bruemmer/Photolibrary/Getty Images001-009_CR14_LR_G5_U6W3L50_A_119233.indd 4001-009_CR14_LR_G5_U6W3L50_A_119233.indd 415/03/12 11:43 AM15/03/12 11:43 AMMost bats have an adaptation to help them find their way in a dark cave.This adaptation is called echolocation.The bat makes high-pitched squeaking sounds and listens for an echo.The echo helps it find out where things are.In some places,bats hibernate in caves in the winter.They dont stay asleep all winter.They usually wake up from their dormant state for a short time every 15 to 30 days.In cold climates,bears may also spend the winter in caves.The air is warmer inside the cave.It helps to insulate animals from the cold.The Virginia big-eared bat hibernates in caverns in West Virginia.Bears go into a deep sleep in winter.Some scientists say this is a kind of hibernation.5Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:505(t)AFP/Getty Images/Newscom,(b)Juniors Bildarchiv/Alamy001-009_CR14_LR_G5_U6W3L50_A_119233.indd 5001-009_CR14_LR_G5_U6W3L50_A_119233.indd 515/03/12 11:43 AM15/03/12 11:43 AMDeeper inside the cave is the twilight zone.It is cool and damp here.Many of the creatures living here are troglophiles,or cave lovers.They may live in caves for all of their lives,but they can also survive outside.Some spiders,earthworms,beetles,frogs,and crickets are troglophiles.The twilight zone has little food or light.The animals living here have adaptations so they can survive in these conditions.They use senses other than sight,such as hearing or touch,to get food and find their way around.The glowworm is also a troglophile.It is the larva of an insect called a fungus gnat.Its adaptation is lighting up its abdomen to attract prey.The glowworm spins a sticky web and then switches on its light.It caches tiny insects in its web until it needs to eat a meal.A glowworm can turn off its light if it hears a noise.6Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:506blickwinkel/Alamy001-009_CR14_LR_G5_U6W3L50_A_119233.indd 6001-009_CR14_LR_G5_U6W3L50_A_119233.indd 615/03/12 11:43 AM15/03/12 11:43 AMThe New Zealand cave weta is a kind of cricket that lives on the undersides of cave roofs.It has antennae that are seven times longer than its body.It uses its antennae to help it move around and find food.This agile insect also has long,strong legs.It can jump more than 6 feet!ADAPTING TO SILENCEIn places where there is little food,its useful to be quiet to avoid being eaten!The African cave cricket does not chirp to communicate.Instead,it uses its wings to send out doughnut-shaped puffs of air called vortices.Only other cave crickets can feel these vortices.The New Zealand cave wetas long legs help it to get away from danger.7Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:507(t)Natural Visions/Alamy,(b)Premaphotos/Alamy001-009_CR14_LR_G5_U6W3L50_A_119233.indd 7001-009_CR14_LR_G5_U6W3L50_A_119233.indd 715/03/12 11:43 AM15/03/12 11:43 AMWhat do animals eat in a cave?Plants cant grow in the dark,but food comes into caves in different ways.Rain and streams wash in twigs,leaves,and seeds,and also insects.There is plant material in the droppings of animals such as bats and cave crickets.These are good sources of food for cave creatures.After molds,fungi,and bacteria break down all this material,microscopic animals can eat it.These microscopic animals are eaten by larger cave dwellers.Then the larger animals are eaten by other predators.CAVE LIONSSome scientists believe the European cave lion lived between 12,000 and 40,000 years ago.It was much bigger than todays lions.Skeletons of animals that die in caves can be preserved for a long time.This is because conditions inside caves rarely change.Scientists learned about these big cats from their very old bones.STOP AND CHECK Why do animals need adaptations to live in caves?8Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:508CLAY BRYCE/AFP/Newscom001-009_CR14_LR_G5_U6W3L50_A_119233.indd 8001-009_CR14_LR_G5_U6W3L50_A_119233.indd 815/03/12 11:43 AM15/03/12 11:43 AMSmall insects such as mosquitoes,gnats,glowworms,cricketsSpidersCentipedes BeetlesFrogsSporesBacteriaThe nutrients in guano,or bat droppings,and other materials are broken down and recycled by some cave creatures and microscopic organisms.These creatures are eaten by larger predators.GuanoEarthwormsBatsTiny insects,mitesCave siltMatter carried by waterMineralsFungiMold CAVE FOOD WEB9Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:509001-009_CR14_LR_G5_U6W3L50_A_119233.indd 9001-009_CR14_LR_G5_U6W3L50_A_119233.indd 915/03/12 11:43 AM15/03/12 11:43 AMImagine going deep underground into the dark zone of a cave.There is no light and no plants grow.It is dark and silent,and the air is still.Life in the Dark ZoneAnimals that live in the dark zone all the time are called troglobites,or cave dwellers.They have adaptations,such as small bodies,long limbs,and long antennae.They can pick up small vibrations or smells.These adaptations help them to move about and forage for food in the pitch-black space.This insect,called a dipluran,has long antennae and two tails.Dark and Surprising PlacesChapter TWO 10Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50Dante Fenolio/Photo Researchers/Getty Images(t)TomHartman/OxfordScientific/GettyImages(b)DanteFenolio/PhotoResearchers Inc010-018_CR14_LR_G5_U6W3L50_A_119233.indd 10010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1015/03/12 11:46 AM15/03/12 11:46 AMMany troglobites have different adaptations from the animals that live above ground.Animals living in the dark zone usually have tiny eyes,or no eyes at all.Eyes are not useful if you live in the dark.Most animals living above ground have coloring in their skin called pigment.Pigment is an adaptation to protect animals from the sun or give them camouflage.Pigment is not needed in the dark zone of a cave.Some animals in caves have skin that is nearly see-through.These cave dwellers could not live for long in the world outside.This adapted daddy longlegs has long legs,a tiny body,and is blind.This pseudoscorpion has long pincers,but no eyes.11Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50(t)Tom Hartman/Oxford Scientific/Getty Images,(b)Dante Fenolio/Photo Researchers,Inc.010-018_CR14_LR_G5_U6W3L50_A_119233.indd 11010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1115/03/12 11:46 AM15/03/12 11:46 AMENTRANCE ZONETWILIGHT ZONEDARK ZONETROGLOBITESTROGLOXENESTROGLOPHILESSTYGOBITESSTYGOPHILESSTYGOXENES12Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50Illustration:Yasin Karadeniz010-018_CR14_LR_G5_U6W3L50_A_119233.indd 12010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1215/03/12 11:46 AM15/03/12 11:46 AMThe Texas blind salamander senses its prey moving in the water.This cave crayfish has no pigment.Aquatic Cave DwellersMany caves have networks of underground streams and ponds.There may be aquatic animals living in and around the water.Aquatic cave dwellers that cant live outside the cave are called stygobites.Stygobites include blind,pale-colored fish,salamanders with no eyes,and crustaceans with no pigment.Stygoxenes are aquatic creatures that come from outside the cave.Stygophiles are water lovers that may spend time outside the cave as well as inside it.13Program:CR 14Component:LRG5U6W3 APDFVendor:Learning MediaLevel:50(l)Dante Fenolio/Photo Researchers/Getty Images,(r)Tom Uhlman/Alamy010-018_CR14_LR_G5_U6W3L50_A_119233.indd 13010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1315/03/12 11:46 AM15/03/12 11:46 AMExtreme Cave DwellersCave creatures have been found in unusual places.In 2001,tiny stygobites were found in caves under the desert in Western Australia.They looked like shrimp.Some caves provide even more hostile conditions.These caves are too cold,too hot,or too toxic for most cave creatures to live in.Yet microscopic forms of life have been found living in these places.Animals that are adapted to live in extreme conditions are called extremophiles.This scientist is fishing for aquatic animals down a hole drilled in the desert.14Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50W F Humphreys,Western Australian Museum010-018_CR14_LR_G5_U6W3L50_A_119233.indd 14010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1415/03/12 11:46 AM15/03/12 11:46 AMGreenlands ice caves have frigid conditions.Most animals could not survive in them.But microscopic creatures have been found there.These creatures can cope with the caves sub-zero temperatures.Cueva de Villa Luz in Mexico is another extreme cave.It has fumes of a toxic gas called hydrogen sulfide.Scientists call the microbes that live on this gas names such as snottites,blue goo,and slime balls!Extremophiles live in Greenlands frozen ice caves.This type of bacteria in Mexicos Cueva de Villa Luz lives on toxic gas.STOP AND CHECKHow are creatures living deep inside caves diff erent from animals living above ground?Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:5015(t)moodboard/Alamy,(b)Stephen Alvarez/National Geographic/Getty Images010-018_CR14_LR_G5_U6W3L50_A_119233.indd 15010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1515/03/12 11:46 AM15/03/12 11:46 AMMany cave creatures couldnt survive in our world.The adaptations that help them live underground would make it dangerous for them above the surface.How do we know which features of cave creatures are adaptations?And how do we learn how these adaptations help animals to survive?Scientists try to find the answers to these questions.They go underground to observe and photograph cave animals to find out about them.16Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50Mark Moffett/Minden Pictures/Getty images010-018_CR14_LR_G5_U6W3L50_A_119233.indd 16010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1615/03/12 11:46 AM15/03/12 11:46 AMAnimals living deep inside caves cant travel easily to other places.Scientists have found some rare species.They may bring the creatures up to Earths surface.The scientists mimic the conditions of caves in laboratories and examine the creatures closely.An amazing range of creatures has been found in caves.But we dont understand everything about these animals and the way they live.There are still many things to learn about life in caves.17Program:CR 14Component:LRG5U6W3-APDFVendor:Learning MediaLevel:50Robbie Shone/Aurora/Getty images010-018_CR14_LR_G5_U6W3L50_A_119233.indd 17010-018_CR14_LR_G5_U6W3L50_A_119233.indd 1715/03/12 11:46 AM15/03/12 11:46 AMSummarizeUse details from Cave Creatures to summarize how living thi