原版英语RAZ 教案(Z1) The Amazing Undersea Food Web.pdf

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1、The Amazing Undersea Food WebA Reading AZ Level Z1 Leveled BookWord Count:1,785Visit www.readinga- for thousands of books and materials.WritingImagine being an oceanographer exploring the twilight zone.Write a journal entry about your findings,including details from the book.ScienceChoose one of the

2、 four ocean zones.Research to learn more about this zone and write a paper sharing your findings.Connectionswww.readinga-The Amazing Undersea Food WebXZ1Z2Written by Penny Atcheson and Elizabeth FoxLEVELED BOOK Z1The Amazing Undersea Food Webwww.readinga-How are animals from the four ocean zones con

3、nected by the undersea food web?Focus QuestionWritten by Penny Atchesonand Elizabeth FoxThe Amazing Undersea Food WebLevel Z1 Leveled Book Learning AZWritten by Penny Atchesonand Elizabeth FoxIllustrated by Cende HillAll rights reserved.www.readinga-Photo Credits:Front cover:Corel,Inc.;title page,pa

4、ge 10:Photodisc/Getty Images;pages 3,14(both):ArtToday;pages 4,15:Minden Pictures/SuperStock;page 5:courtesy of Prof.Gordon T.Taylor,Stony Brook University/NSF Polar Programs/NOAA;page 7:courtesy of Jacques Descloitres,MODIS Rapid Response Team,NASA/GSFC;page 11:Marty Snyderman/Corbis;page 12:courte

5、sy of Mike White/Florida Keys National Marine Sanctuary/NOAA;page 13:courtesy of Florida Fish and Wildlife Conservation Commission;page 17:John Anderson/D;pages 18,20(both):courtesy of OAR/National Undersea Research Program/NOAA;page 21:courtesy of OAR/National Undersea Research Program,Woods Hole O

6、ceanographic Institute/NOAA;Page 22:Chittima Kasa/Dabyssal zoneaccumulationanemoneaphotic zonebioluminescencechlorophylldisphotic zoneeuphotic zonefaultsphotosynthesisphytoplanktonsnorkelingsubmersiblestrencheszooplanktonWords to KnowCorrelationLEVEL Z1WXN/A60Fountas&PinnellReading RecoveryDRA3Table

7、 of ContentsLet Me Introduce Myself .4The Food Web .8Life in the Sunlit Zone .10The Twilight Zone.15The Midnight Zone.19Back on Top .22Glossary .23 The Amazing Undersea Food Web Level Z14Let Me Introduce MyselfThe ocean,where I live,is an enormous buffet table for everything in it and for many land

8、animals,including humans.When you think of the ocean food web,you might think of fierce great white sharks devouring their prey,or enormous blue whales gulping tons of krill.Or you might think of giant stands of seaweed being devoured by everyone,like an underwater salad bar.But did you know that mo

9、re than 90 percent of all sea creatures end up being eaten by other sea creatures?That means that almost every organism in the ocean ends up getting eaten by another sea creature at some point or other.And almost every sea creature eats other sea creatures.The blue whale is the largest animal on Ear

10、th.5But there are little organisms that almost always get eaten but do not actually eat anything themselves.They are the most microscopic species in the ocean,yet they form the center of the oceans food web.Some people might think its a raw deal to be food for everybody else,but I find it to be quit

11、e a powerful job.Let me back up and introduce myself properly.Phytoplankton(FY-tow-plank-ton)is my name.Im an algae,which is almost like a very tiny plant.But unlike plants,I have no roots,so Im not attached to the ground or sea floor.Im free to float around with the ocean currents.I prefer to remai

12、n near the surface of the sea,since Im quite fond of sunlight,and I can be found in every ocean on Earth.These microscopic phytoplankton are called diatoms.The Amazing Undersea Food Web Level Z16Like plants,I make food through a process called photosynthesis,rather than eating it.I use chlorophyll t

13、o capture the Suns energy and use it to convert minerals and nutrients from seawater into food.Just as in plants,chlorophyll makes me green.But Im so tiny that you can only see the color when there are billions upon billions of us in one place.Chlorophyll in plant cells converts sunlight and nutrien

14、ts into food.SUNLIGHTNUTRIENTS FROM WATERCELLCHLOROPHYLL7Fortunately,there are billions upon billions of us.Thousands of phytoplankton can be found in one cup of seawater.All that photosynthesis going on helps provide the Earths atmosphere with well over half of its oxygen.We are also a good indicat

15、or of the oceans health.Scientists can see large patches of phytoplankton from space.They can get information about the levels of pollution in the water when they see us struggling or dying off.But in my opinion,our most important job is providing the center of the food web for the entire ocean.We f

16、eed all ocean life forms directly or indirectly,from the smallest creature to the largest.A phytoplankton and zooplankton bloom shows up as light streaks in this photo taken from space.The Amazing Undersea Food Web Level Z18The Food WebHeres how it works:think about a simple tuna fish sandwich.Tuna

17、are relatively large fish,and they eat smaller fish called mackerel.To make 1 kilogram(2.2 lbs)of tuna flesh,the tuna had to eat about 10 kilograms(22 lbs)of mackerel.Those 10 kilograms of mackerel had to eat 100 kilograms(220 lbs)of an even smaller fish called herring.And those 100 kilograms of her

18、ring devoured a full 1,000 kilograms(2,200 lbs)of zooplankton.Zooplankton are microscopic animals.They include tiny animals such as krill,which look like little shrimp,and the larvae and babies of crabs,jellyfish,shrimp,and other fish.To support those 1,000 kilograms of zooplankton,10,000 kilograms(

19、22,000 lbs)of phytoplankton were eaten.Tuna eat mackerel,which eat herring.Herring eat zooplankton,which eat phytoplankton.9To give you an idea of just how much life I support,Ill take you through the ocean from the surface,where I live,down to the deepest trenches on the ocean floor.DisphoticZoneAp

20、hoticZone2,000 mOcean TrenchAbyssalZoneEuphotic Zone1,000 m5,000 m200 m3,000 m4,000 m0 mThis cross section shows the different zones of the ocean.The Amazing Undersea Food Web Level Z110Life in the Sunlit ZoneThe euphotic(yoo-FOE-tic)zone,or sunlit zone,is the top level of the ocean.It extends about

21、 200 meters(660 ft)down from the surface.Theres lots of sunlight here,so we phytoplankton,along with ocean plants,love it.Consequently,most of the animal species in the ocean can also be found here.Red and green algae,also known as seaweed,cover much of the shallow ocean floor in the euphotic zone.E

22、normous giant kelp grow in thick forests,almost like forests on land,and provide shelter for many sea animals.Sea urchins live in the protected waters at the base of the kelp,and sea otters feed on those urchins.Sea otters also wind long strands of kelp around their bodies while they sleep in order

23、to keep from drifting away.Otters feed and live in the sunlit zone.11Almost all the seafood humans eat comes from the euphotic zone.Clams,mussels,and oysters live on shallow ocean floors.Lobsters and crabs scuttle about in coral reefs and among seaweed beds.Most species of fish,including salmon,tuna

24、,mackerel,cod,and swordfish,stay up in the sunlight where there is plenty to eat and good light for hunting.Though there are squid and octopuses in the deeper zones,most of the ones that humans eat come from the euphotic zone.Most familiar fish,such as this hammerhead shark,live in the euphotic zone

25、.The Amazing Undersea Food Web Level Z112The euphotic zone is also home to coral reefs,which hold most of the oceans plant and animal species.These fragile and beautiful areas are formed by the accumulation of the skeletons of small animals called coral polyps.They are found in clear,tropical waters

26、 where there is lots of sunlight.Sea fans,brain coral,clown fish,angelfish,lion fish,moray eels,sharks,shellfish,crabs,and lobsters all make the coral reef a colorful and busy place.Anemonesanimals that look like beautiful flowering plantscatch zooplankton with their stinging tentacles.Jellyfish swa

27、rm in massive numbers,attracting the sea turtles that love to eat them.Coral reefs also provide a safe haven for the young of many creatures that will live in the open ocean as adults.Colorful coral reefs are the sunlit zones most popular areas.13Humans love snorkeling and diving in the euphotic zon

28、e,especially around coral reefs.And they take thousands of tons of fish,both for food and for pets in tropical aquariums,from these surface waters.Unfortunately,all this human activity,along with pollution,threatens the well-being of coral reefs and other areas in the euphotic zone.Coral polyps are

29、often killed by pollution,boat engines breaking them,or divers stepping on them,and once the corals die,all the other reef life suffers as well.Entire populations of fish can drop dangerously low from overfishing.Boats,anchors,and divers can break coral.The Amazing Undersea Food Web Level Z114One no

30、ndestructive way to sample ocean life in the euphotic zone is to look into a tide pool.A tide pool is a small pool of water that remains when the tide goes out.You can find mussels,sea stars,urchins,clams,barnacles,and snails.You might even see an octopus,or you may spot a hermit crab scurrying abou

31、t in another animals shell.You dont even have to get wet to see all the life that depends,directly or indirectly,on me and my fellow phytoplankton.If you visit a tide pool,you may get a glimpse of a spiny sea urchin.15The Twilight ZoneAs you go below the euphotic zone,the water begins to get darker,

32、colder,and heavier.You are now entering the twilight zone.It begins at about 200 meters(656 ft)and goes to a depth of about 1,000 meters(3,280 ft).The pressure in this zone would crush a person,but the life forms that live here have adapted to the pressure.The twilight zone,also called the disphotic

33、(dis-FOE-tic)zone,doesnt have enough light to support photosynthesis and plant life,but some animals do make their homes here.Others,such as whales,visit from the euphotic zone.Permanent residents include octopuses,squid,and strange-looking fish such as the hatchet fish and the viperfish.Many fish t

34、hat live in this zone often have huge mouths with big,curved teeth.Because it is so hard to see,the fish dont hunt.Rather,they simply hold open their fearsome mouths,waiting for something to swim in.Many of them are black or dark red to blend in with the dark water.This angler fish is small but scar

35、y.The Amazing Undersea Food Web Level Z116The famous giant squid also lives in this zone.Until fairly recently,no giant squid had ever been seen alive.The squids bodies occasionally washed up on shore or were found in the stomachs of sperm whales.Though a few people have seen it at the surface,and a

36、 few scientists have seen it in the disphotic zone,the giant squid still remains a mystery.Sperm whales have sucker scars from fighting with giant squid.17Many animals in this zone depend on a diet of what scientists call“marine snow,”which is a nice name for dead phytoplankton and zooplankton!When

37、we die,our bodies drift slowly down through the ocean layers like snow falling through the air.So even where we dont live,phytoplankton are eaten.Octopuses live in both the euphotic and disphotic zones.The Amazing Undersea Food Web Level Z118Tiny bioluminescent animals glow beautifully in the pitch-

38、black depths.19The Midnight ZoneThis totally dark region of the ocean contains 90 percent of the oceans water,but almost none of its life.It extends from 1,000 to 5,000 meters(3,28016,404 ft)and below.The pressure is so great that it can crush almost anything,including most submarines,and the temper

39、ature is near freezing.But there is some life in the midnight zone,or aphotic(ay-FOE-tic)zone,if you look closely.Many of the tiny animals that live here,such as the lantern fish,have little lights running up and down their bodies.The light comes from a special process called bioluminescence.This is

40、 the same process that produces light in fireflies.Jellyfish,squid,fish,and even bacteria are bioluminescent in this zone,where there is no sunlight.These lights make it possible for animals to see and communicate with each other.These lights also help them find mates or food,and they also make them

41、 incredibly beautiful.Some oceanographers divide the midnight zone into two additional zones:the abyssal zone and ocean trenches.The abyssal zone is totally dark,and it covers much of the ocean floor,including vast plains,mountains,valleys,and canyons.The Amazing Undersea Food Web Level Z120Ocean tr

42、enches occur along faults where large plates of the Earths crust come together.The colliding plates create canyons and cracks of up to 10,000 meters(32,808 ft)deep.You would think that nothing could survive at the bottom of a trench in the darkness,cold,and pressure.But openings at the bottom of the

43、 trenches spew hot water and minerals from deep within the Earth.(Left)This chimney,called a black smoker,spews hot minerals.The warmth and nutrients support crabs(below),tube worms,and other animals.21Animals living in this zone have taken advantage of the warmth and nutrients.Special kinds of bact

44、eria can use these nutrients in the same way that phytoplankton use sunlight.Tube worms,shrimp,and giant clams can all be found feeding on these bacteria around the openings,or chimneys.These chimneys were only recently discovered.Only a few submersibles,or submarines,have been built strong enough t

45、o withstand the enormous pressure at the bottom of a trench.This submersible can withstand the enormous pressure of an ocean trench.The Amazing Undersea Food Web Level Z122Back on TopSo you see,even though phytoplankton are only at the top of the ocean,were at the center of the food web,supporting a

46、ll other life in the sea.Whether you enjoy the ocean for the beauty of coral reefs,the mystery of the abyssal zone,or some tasty fish and chips,you have us phytoplankton to thank.23Glossaryabyssal zone(n.)the part of the aphotic zone that includes the deep ocean floor(p.19)accumulation(n.)a piling u

47、p of material over time(p.12)anemones(n.)plantlike,marine animals whose tentacles often look like flower petals(p.12)aphotic zone(n.)the bottom ocean zone,which receives no sunlight(p.19)bioluminescence(n.)the light or the emission of light created by a biochemical process within a living thing(p.19

48、)chlorophyll(n.)a substance in plant cells that transforms water,air,sunlight and nutrients into food(p.6)disphotic zone(n.)the middle ocean zone,which receives very little sunlight and contains no plants and few animals(p.15)The Amazing Undersea Food Web Level Z124euphotic zone(n.)the top ocean zon

49、e,which contains almost all of the oceans life(p.10)faults(n.)cracks in Earths crust along which movement occurs(p.20)photosynthesis(n.)the process by which chlorophyll in plant cells transforms sunlight,water,air,and nutrients into food(p.6)phytoplankton(n.)single-celled algae that live in a body o

50、f water(p.5)snorkeling(n.)the act of swimming using a short,curved tube that extends above the waters surface and allows the swimmer to breathe while under water(p.13)submersibles(n.)small vessels that can operate underwater,especially at deep levels(p.21)trenches(n.)cracks in the seafloor;long ditc