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1、Blue Whales:Giant MammalsA Reading AZ Level Z Leveled BookWord Count:1,458Visit www.readinga- for thousands of books and materials.WritingUsing information from this book,write a persuasive essay answering the question:“Why are blue whales fascinating?”ScienceCompare blue whales to humans.Use pictur

2、es of each to label the similarities and differences between these two mammals.ConnectionsLEVELED BOOK AWritten by Louise FrechetteBlue Whales:Giant MammalsGIANTS OF THEANIMAL WORLDLEVELED BOOK ZLEVELED BOOK Zwww.readinga-www.readinga-Written by Louise FrechetteHow does the blue whales anatomy enabl

3、e it to live in the ocean?Focus QuestionBlue Whales:Giant Mammals16Glossarybaleen(n.)a material in the mouth of certain whales that filters food from ocean water(p.9)buoyancy(n.)the ability or tendency to float(p.6)cetaceans(n.)ocean mammals,including whales,dolphins,and porpoises(p.8)crustaceans(n.

4、)members of a group of mostly aquatic invertebrates,such as crabs,lobsters,and shrimp(p.9)flukes(n.)the two halves of a whales tail(p.6)frequencies(n.)the rates of vibration of a sound wave (p.13)gestation(n.)the period when a baby develops inside its mothers body before being born;the development t

5、hat occurs during this time(p.12)keratin(n.)a strong material produced by the bodies of some animals that makes up hair,hooves,claws,feathers,and fingernails(p.10)krill(n.)tiny crustaceans that live in oceans and are food for many other animals(p.9)pectoral(adj.)of,relating to,or located in or on th

6、e chest(p.6)plankton(n.)tiny plants and animals that live on or near the oceans surface(p.11)sonar(n.)a system that sends high-frequency sound waves through water and registers the vibrations bounced back by an object(p.13)16baleenbuoyancycetaceanscrustaceansflukesfrequenciesgestationkeratinkrillpec

7、toralplanktonsonarWords to KnowBlue Whales:Giant MammalsLevel Z Leveled Book Learning AZWritten by Louise FrechetteAll rights reserved.www.readinga-CorrelationLEVEL ZUVN/A50Fountas&PinnellReading RecoveryDRACover:A blue whale leaps out of the water.This behavior is thought to be a method of communic

8、ation.Title page:A blue whale can spray air and condensed water vapor up to 30 feet(9.1 m)in the air.Page 3:Blue whales have fifty to seventy throat grooves,which expand when they feed.Photo Credits:Front cover,back cover:Biosphoto/Biosphoto/Superstock;cover icon:Elena Belyakova/iStock/Thinkstock;ti

9、tle page:Ole Jorgen Liodden/Nature Picture Library/Corbis;page 3:Doc White/;page 4:syntika/iStock/Thinkstock;page 5(background):Andriy Myahkov/iStock/Thinkstock;page 5(foreground):Universal Images Group Limited/Alamy;page 6(main):Mark Carwardine/NPL/Minden Pictures;page 6(inset):Mcasabar/D;page 7:Ja

10、mes Forte/National Geographic Creative;page 9(main):Richard Herrmann/Minden Pictures;page 9(inset):Jean Paul Ferrero/;page 10:Stocktrek Images,Inc./Alamy;pages 11,15:Flip Nicklin/Minden Pictures;page 12:Hiroya Minakuchi/Minden Pictures;page 13:Richard Herrmann/Minden Pictures;page 14(top left):ferli

11、stockphoto/iStock/Thinkstock;page 14(top right):ilfede/iStock/Thinkstock;page 14(bottom left):REX USA/Gonzales Photo/Malthe Ivarsson/PYMCA/Rex;page 14(bottom right):Doc White/NPL/Minden Pictures15ConclusionBlue whales continue to fascinate researchers around the world.In the early to mid-twentieth c

12、entury,so many blue whales were hunted that they were nearly driven to extinction.Blue whales also face other dangers,including collisions with ships in the open ocean.As an endangered species,these whales are protected under the International Whaling Commission.However,hunting bans remain hard to e

13、nforce,and the blue whale population has yet to fully recover.Marine biologists and other scientists study migration movements and feeding patterns in order to better understand how these giants of the deep live and what they can teach us about life and survival in the ocean.By monitoring environmen

14、tal and human-related threats,the goal of keeping blue whales safe from harm and helping their numbers rebound may still be achieved.An estimated ten to twenty-five thousand blue whales live in the worlds oceans.At one time,there were over three hundred thousand.Blue Whales:Giant Mammals Level Z153T

15、able of ContentIntroduction .4Blue Whale Anatomy .5Diet and Feeding .9Whale Range and Habitats .11Those Big Baby Blues .12Call of the Cetaceans .13Conclusion .15Glossary .16Blue Whales:Giant Mammals Level Z14Researchers know that only male blue whales sing.They have also found that whales in one par

16、t of the world sing songs that are slightly different from songs sung by whales elsewhere.In calm seas,their songs can be detected by other blue whales up to 1,000 miles(1,600 km)away.The blue whales of the Indian Ocean have the most musical and versatile songs,producing four separate“notes”as they

17、sing.A decibel(dB)is a unit that measures the loudness or softness of a sound.Just How Loud Is a Blue Whales Song?Just How Loud Is a Blue Whales Song?Conversation:70 dBJet engine:140 dBRock concert:150 dBBlue whale call:180 dB4IntroductionA research vessel motors along the glassy surface of the Paci

18、fic Ocean off the coast of California.Onboard is a group of marine biologists continuously scanning the horizon for signs of Earths largest creature.Soon enough,they catch sight of what they are looking fora towering water spout three stories high erupting from the oceans surface.Its source is Balae

19、noptera musculusthe majestic blue whale.Blue whales live in all of the worlds oceans,with one of the largest populations inhabiting the waters of the northeastern Pacific Ocean.An estimated 2,800 blue whales travel annually between Alaska and Costa Rica,a country in Central America,in search of temp

20、erate waters and food.Scientists attempt to locate the blue whales to learn more about the behavior and migration habits of these giant mammals.How Big Is It?How Big Is It?Human Height:6 feet(1.8 m)Weight:175 pounds(79.4 kg)Blue whale Length:100 feet(30.5 m),Weight:200 tons(181.4 mt)13Call of the Ce

21、taceansNot only are blue whales the largest animals in the world,but they are also the loudest.Their sounds,which are louder than a jet engine,can travel for miles through the water.Yet even though whale sounds are powerful,they are difficult for people to hear since they are produced at extremely l

22、ow frequencies.The frequencies are too low for the human ear to detect without special equipment.Some scientists think blue whale sounds,or songs,function as a type of sonar that allows the whales to navigate dark ocean waters.Other scientists think that these whales sing to communicate with each ot

23、her about where they are and what theyre doing.When a blue whale leaps out of the water,the behavior is called breaching.Blue Whales:Giant Mammals Level Z5Blue Whale AnatomyThe blue whale is the largest known animal to ever inhabit Earth.Even the most gargantuan of the dinosaurs was no match for a b

24、lue whale.Just one of these enormous sea creatures is the equivalent of four brontosauruses!A typical adult blue whale weighs in at 200 tons(181.4 mt)and is approximately 100 feet(30.5 m)long.Its tongue weighs as much as an elephant.Its heart is so large that a person could crawl through its main bl

25、ood vessels!What Makes a Blue Whale a Mammal?What Makes a Blue Whale a Mammal?All mammals breathe air have hair on their bodies at some stage in their development are warm-blooded produce milk to feed their babiesA blue whale breathes air through blowholes on the top of its head.A blue whale has a l

26、ayer of fat,called blubber,that helps keep it warm.A blue whale has baleenhairlike structures inside its upper jaw.Blue Whales:Giant Mammals Level Z12Those Big Baby BluesFemale blue whales give birth while wintering in warm waters.The gestation period lasts about one year.At birth,baby blue whales,c

27、alled calves,weigh more than 5,000 pounds(2,268 kg)and measure approximately 25 feet(7.6 m)in length.Within minutes,a calf swims to the surface with its mother to take its first breath.Blue whales give birth in warm waters since newborn calves do not have much insulating blubber.A female whale gives

28、 birth to a calf every two or three years.A blue whale calf has strong bonds with its mother and stays close by for at least the first six months of its life.During that time,the calf consumes up to 100 gallons(378.5 L)of milk and gains over 200 pounds(90.7 kg)every day.After migrating to summer fee

29、ding grounds,the calf is eventually weaned and goes off alone to look for krill.A blue whale is considered mature by the time its ten years old.6A creature as colossal as the blue whale could never live on land because the force of gravity would cause the animals body to collapse on itself.Water,on

30、the other hand,provides buoyancy,which works against gravity and helps support the animal.The only way the blue whale can be so gigantic and still survive is by living in the sea.Blue whales may be humongous,yet they still move with ease and grace through their watery habitat.They typically cruise a

31、t 5 miles per hour(8 kmph),although they can travel at speeds of up to 20 miles per hour(32 kmph).A blue whales graceful torso is long,with a flexible spine and elongated pectoral fins for maneuvering through the fluctuating ocean waters.On its tail is a pair of enormous flukes,or lobe-like structur

32、es.When a whale dives,its flukes rise from the ocean and create a circular“flukeprint”on the waters surface.Whale watchers look for flukeprints on the waters surface to locate whales.11Whale Range and HabitatsBlue whales can be found gliding through the depths of every ocean on our planet.While some

33、 species of whales travel in groups called pods,blue whales typically travel alone or in pairs.They migrate from higher to lower latitudes during the winter months in search of krill.A popular location for Pacific blue whales is the Costa Rica Dome,off the southern coast of Central America.Water cur

34、rents there force frigid air to the surface during summer months,resulting in large amounts of plankton and krill.=Blue whale rangeWhere Blue Whales LiveWhere Blue Whales LiveNORTH AMERICAAFRICAAUSTRALIAANTARCTICAASIAEUROPESOUTH AMERICAPACIFIC OCEANPACIFIC OCEANINDIAN OCEANATLANTIC OCEANThe grooves

35、on a blue whales throat expand to help it gulp up to 17,000 gallons(64,352 L)of water at a time.Blue Whales:Giant Mammals Level Z7Blue whales have lungs and breathe air just like humans,but on a much larger scale.Whale lungs can hold more than 1,000 gallons(3,785.4 L)of air,while adult human lungs h

36、old only about 1.3 gallons(5 L).A whale rises to the surface and exhales through the pair of blowholes at the top of its head,spraying air and condensed water vapor 30 feet(9.1 m)into the air.Then it quickly inhales,filling its massive lungs with air in under two seconds.The blowholes connect to the

37、 whales lungs through its trachea.A blue whale cannot breathe through its mouth.A whale takes several breaths before its descent into the ocean depths.A flap covers its blowholes when the whale dives.Blue whales typically remain underwater for twenty to thirty minutes.Classified as shallow divers,th

38、ey rarely go deeper than 700 feet(213.4 m).In comparison,the sperm whale can reach depths more than four times greater.The two blowholes on a blue whales head are like human nostrils.Blue Whales:Giant Mammals Level Z10Baleen consists of keratinthe same substance found in human hair and fingernails.I

39、ts fringed on the end,making it seem as though a mustache is growing inside the whales mouth.The baleen in a whales mouth functions as a strainer.When feeding,a blue whale takes an enormous gulp of seawater teeming with krill.Its throat expands to accommodate thousands of gallons of seawater.Next,it

40、 closes its mouth and uses its massive tongue to push the water through the baleen and out into the sea.Since krill cannot pass through the baleen,they remain in the whales mouth and are eventually swallowed whole.A blue whale eats about forty million krill each day.Blue whales make multiple dives i

41、nto a swarm of krill while feeding.A whale must consume huge quantities since it burns up to 3 million calories(300,000 kcal)per day.A blue whale has up to eight hundred baleen plates in its mouth.baleen8Even the shallowest of tropical waters can get cool,but that doesnt present a problem for blue w

42、hales.Like all cetaceans,these whales have a thick layer of fatty tissue called blubber just beneath their skin that serves to insulate them from cold temperatures.Since blubber is not as dense as water,it provides buoyancy and makes it easier for blue whales to float and swim.Female whales build up

43、 extra layers of blubber before giving birth so they wont have to leave their newborn calves to search for food.The surplus energy stored in their blubber tides them over until they can get food.epidermisdermisblubberconnective tissuemuscleBlubber provides insulation and helps whales maintain food r

44、eserves.9Diet and FeedingWhen blue whales dive,they are searching for their favorite mealtiny shrimplike crustaceans called krill.While it may seem strange that the largest animal in the world feeds on one of the smallest,it does so for good reason.Blue whales are huge,but their throats are actually

45、 quite narrow.A blue whales esophagus is only inches wide,making it impossible to swallow anything big.In addition,blue whales lack teeth and must swallow their food whole.Scientists divide whales into two groups.Some,like sperm whales,have teeth and are classified in the suborder Odontoceti,while others,like blue whales,have baleen,which places them in the suborder Mysticeti.Instead of teeth,blue whales have hundreds of plates of baleen lining their upper jaw.Krill are the main staple of a blue whales diet.Krill often swarm near the waters surface.Blue Whales:Giant Mammals Level Z