原版英语RAZ 教案(Z1) Symbiotic Wildlife_DS.pdf
Visit www.readinga- for thousands of books and materials.WritingImagine you are a scientist studying the ocean.What symbiotic relationships would you see?Write a journal entry detailing your discovery.ScienceChoose and research one symbiotic relationship from the book or another source.Write a report that includes details about both species and their partnership.ConnectionsSymbiotic WildlifeA Reading AZ Level Z1 Leveled BookWord Count:2,469www.readinga-LEVELED BOOK Z1Symbiotic WildlifeZZ1Z2Written by M.T.Stark www.readinga-How do symbiotic relationships work,and why are they important?Focus QuestionSymbiotic WildlifeWritten by M.T.Stark24Glossaryassumes(v.)places oneself in a particular position or role(p.11)fertilized(v.)combined male and female reproductive cells to create a new animal or plant(p.18)interdependent(adj.)dependent on each other,as in people,groups,or organisms in an ecosystem(p.6)intimidating(adj.)frightening or overwhelming(p.9)mucus(n.)a thick,slimy liquid created in a body to protect tissues and keep them wet(p.7)nocturnal(adj.)active at night rather than during the day(p.12)parasites(n.)plants or animals that grow on and feed off others(p.10)refuge(n.)a place of safety,comfort,or protection(p.7)species(n.)a group of living things that are physically similar and can reproduce (p.4)sustainability(n.)the use of natural resources in a way that prevents them from being used up or permanently damaged(p.23)symbiotic(adj.)of or relating to a beneficial relationship between different kinds of organisms(p.4)venomous(adj.)having the ability to inject venom,a poisonous fluid,by striking,biting,or stinging(p.5)2423Although each symbiotic relationship is a little different and provides each species with a slightly different benefit,all have a positive impact on the world,promoting diversity and sustainability for all living things.The end result is that fish,birds,humans,and many other organisms on our planet have a better chance of surviving,reproducing,and living longer,healthier lives.Grazing impalas stir up bugs,which gives baboons an easy meal.Baboons pay them back by sounding a warning if danger approaches.Symbiotic Wildlife Level Z1CorrelationLEVEL Z1WXN/A60Fountas&PinnellReading RecoveryDRASymbiotic WildlifeLevel Z1 Leveled Book Learning AZWritten by M.T.StarkAll rights reserved.www.readinga-Front cover:A yellow-billed oxpecker positions itself on the neck of an impala before cleaning its ears.Title page:A greater short-nosed fruit bat feeds on a banana plant.The banana is a bat-dependent plant.Pollen is carried on the bats fur to other banana plants,allowing them to reproduce.Page 3:A school of yellow tang fish clean the algae from a green sea turtle.Photo Credits:Front cover:Pete Oxford/Minden Pictures;title page:Merlin Tuttle/BCI/Photo Researchers,Inc.;page 3:Masa Ushioda/age fotostock/SuperStock;page 4:Juniors Bildarchiv/Alamy;page 5:iStock/Kristian Sekulic;page 6:John Pavel/D;page 7:iStock/Derek Holzapfel;page 8:Alexandr Shestopalets/D;pages 9(top),11(top),12:iStock/Diane Labombarbe;page 9(bottom):Richard T Nowitz/C/DAMON/age fotostock;page 10:Jamesdawson/D;page 11(bottom):Tui De Roy/Minden Pictures;page 13:Salpics32/D;page 14:Reinhard Dirscherl/Alamy;page 15(main):Dave Parker/D;page 15(inset):Rafael Angel Irusta Machin/D;page 16:Carol Buchanan/D;page 17:Richard Du Toit/Minden Pictures;page 18:Rolf Nussbaumer Photography/Alamy;page 19:Lorand Schuller/D;page 20:Melinda Podor/Alamy;page 21(main):Juniors Bildarchiv/Alamy;page 21(inset):Gerry Bishop/Visuals Unlimited,Inc.;page 22(main):Ralf Broskvar/D;page 22(inset):Frans Lanting/National Geographic Stock;page 23:Steffen Foerster/Dassumesfertilizedinterdependentintimidating mucus nocturnal parasites refugespeciessustainabilitysymbioticvenomousWords to Know233Table of ContentsIntroduction .4Finding Food and Giving Protection .7Helping with Personal Hygiene .10Sharing a Home .12Teaming Up to Find Food .15Hitching a Ride .16Pollinating and Fertilizing .18Spreading Seeds .20Conclusion .22Glossary .24Symbiotic Wildlife Level Z122ConclusionThe world would be a very different place without symbiotic relationships.In the absence of these natural partnerships,many species would be more vulnerable to predators and pests,more likely to be isolated in smaller patches of habitat,less apt to bloom and spread,or faced with fewer choices for food.Not only would the partners suffer,but so too would other inhabitants of our ecosystems.Scientists are still learning about how these special relationships work and are discovering new ones all the time.From shallow,sunlit waters to deep,dark caverns,Earth is full of symbiotic partners that help each other survive and thrive.Sooty shearwaters and tuataras have a special living arrangement on the shoreline cliffs of New Zealand.4IntroductionLiving in the wild is challenging.Food can be scarce,good homes are hard to find,and pests arewell,pests.Plus,theres almost always something out to eat you.Those reasons are why many species in the wild form unusual relationships in which they work together at separate tasks that benefit each other.For example,one may offer safety from predators in exchange for a good cleaning or a steady supply of food.Such partnerships are called symbiotic relationships.The word symbiosis comes from the ancient Greek words for“with”and“living.”Scientists first applied the word to wild species in 1877 while writing about lichenscomplex(and sometimes colorful)organisms typically made up of a fungus and a type of algae that work and live closely together.A crocodile opens wide for a small Egyptian plover bird.The plover cleans bits of leftover food from the crocs teeth.21What the fall cannot do,the agouti can.The agouti is equipped with strong teeth and powerful jaws that enable it to break through a seedpods thick shell and feast on its contents.The agouti eats some of the seeds and scatters others throughout the forest by burying them far from the parent tree.The seeds eventually sprout into trees,and the long process begins all over again.Mistletoe plants in the desert rely on a bird called a phainopepla(fay-no-PEHP-luh)to spread.The phainopepla snacks on mistletoe seeds,which are buried in the plants berries,by using its beak to separate the skin from the berries and then disperses undigested seeds wherever it leaves its droppings.The strong jaws of the small agouti can crack open tough pods.New Brazil nut trees will sprout from droppings left by the agouti.Symbiotic Wildlife Level Z15Since then,scientists have identified symbiotic relationships that exist all around usin deep oceans and dry deserts as well as in mountains and forests.Researchers have discovered unexpected partnerships,such as between a venomous sea anemone(uh-NEM-uh-nee)and a colorful clownfish,or a towering tree and a ground-dwelling rodent.In the wild,these unusual partnerships are not only fascinating but can also mean the difference between life and death for the species involved.Bees,for instance,would have a hard time surviving without the nectar of flowers and,similarly,those same flowers would have a tough time reproducing without the help of bees that distribute their pollen.Pals and PartnersYou may have your own symbiotic relationship at home.Your pet dog,for instance,provides you with love,companionship,and protection.In return,your dog gets food,attention,and a safe place to live.You both benefit.Symbiotic Wildlife Level Z120Spreading SeedsIf youre a tree or another plant,you need a way to spread your seeds to new areas.Otherwise,youll only grow in one place,which leads to crowding and competition for light and water.The odds of your species surviving arent as good as they would be if you could disperse your seeds far and wide to spread new plants that will grow and produce seeds of their own.Many trees and other plants rely on animal partners to help disperse their seeds.One of the most interesting pairings,found in the Amazon rainforest,is that of the Brazil nut tree and a cat-sized rodent called an agouti.The Brazil nut tree is a towering tree that can grow to a height of 200 feet(61 m)or more.Its grapefruit-sized seedpods,which are hard and tough,typically dont split open when they hit the ground,even though they sometimes plummet from heights of 100 feet(30.5 m)or more.Pods of Brazil nuts clustered high in the Brazil nut tree6Symbiotic relationships arent always equal,but those that have endured over thousands or even millions of years tend to last for one reason:both species benefit enough to make the relationship worthwhile.Some scientists believe that these symbiotic relationshipswith different species interdependent on one anotherare a big reason we have so many diverse plants and so much diverse wildlife on Earth.Lets look at some examples of the many types of symbiotic relationships to see how different kinds of living things work together in the natural world.A group of starlings stick close to a red deer for the chance to pick insects off its body.Word WiseThe partners in a symbiotic relationship are called symbionts.19Like bats,honeybees are active pollinators and are essential to plant reproduction.The bees enter flowers to get to their nectar and often fly away covered with flecks of pollen,which are deposited at the next stop.Hummingbirds operate in much the same way,collecting pollen on their feathers and bills as they dart from flower to flower.Flowers offer more than food to some pollinators.Female yucca moths,for example,are picky about where they lay their eggs.They prefer spreading their hundreds of eggs on several yucca flowers.Not only do the eggs find safe homes,but the flowers also benefit because the female yucca moth is spreading pollen as she flits from flower to flower.A honeybee spreads pollen from one dandelion to the next as it gathers nectar.Symbiotic Wildlife Level Z17Finding Food and Giving ProtectionSometimes its nice to know someones got your back.Clownfish,such as the colorful ones that live in the Indian Ocean,need all the help they can get to stay safe from predators.One way they do this is by seeking refuge in the tentacles of venomous sea anemones.Although anemones look like plants,theyre actually marine animals that attach themselves to rocks or other surfaces and then wait for prey to come to them.When small fish or shrimp brush against an anemones soft tentacles,they are exposed to a toxin.The toxin paralyzes them long enough for the anemone to pull them to its mouth and eat them.Anemones have a different relationship with clownfish,though.Clownfish have figured out a way to build up immunity to the anemones venom.They do this by touching the anemones tentacles once or twice,taking a break,and then doing it again and again.This repetition gradually provides the clownfish with a protective layer of mucus on its skin.Sea anemoneSymbiotic Wildlife Level Z118Pollinating and FertilizingBats do more than just inspire spooky stories.For many plants around the world,bats are their ticket to survival.In return,those plants provide sweet nutrition for their furry,winged friends.Bats are part of an important group of animals called pollinators.These animals transport pollen from the stamens,or male parts of flowers,to the pistils,or female parts,as they eat,allowing the plants to be fertilized,reproduce,and grow.Often working at night,bats love to sink their heads deep into the center of a flower to drink sugary nectar and eat the protein-rich pollen.After visiting a blossom,the bats are often speckled with bits of sticky pollen.That pollen is then transferred to the next flower that the bat visits,providing a regular exchange of pollen between flowers and a steady source of nectar and delicious pollen for the hungry bats.A long-nosed bat feeds on the nectar and pollen of the pollen-rich agave plant.Bats are the main pollinators of agaves and cacti within their range.8The mucus shields the clownfish from any harmful contact with the anemone and allows the fish to swim among the anemones tentacles without getting hurt.So,when a predator arrives to have a clownfish for lunch,the clownfish can dive into the safe arms of the anemone.When the predatory fish gets too close to the anemone,the anemones stinging cluster of tentacles kill it and provide a meal for both members of this partnership.A cautious striped clownfish hides from predators among the protective tentacles of a venomous sea anemone.17Remoras arent the only creatures with strange things on their heads.Some hermit crabs that live in the Mediterranean Sea wear an odd-looking hat.The hat is actually a hitchhiking sea anemone.The sea anemones long tentacles are venomous,but the hermit crab is protected from them by its hard shell.The anemone protects the hermit crab from predators.In exchange,the anemone benefits from the crabs messy habits when it eats scraps of food that the crab doesnt eat.Not all symbiotic hitchhikers are in the sea.In Africa,a small bird called an oxpecker often hitches a ride on the back of a hippopotamus instead of exerting energy searching for insects on its own.The bird picks bugs off the skin of the hippo and eats them.The oxpecker gets a meal and easy transport,and the hippo gets picked clean of pesky insects.A group of oxpecker birds hitch a ride on the back of a hippopotamus.In return for the ride,they pick the hippo clean of bugs.Symbiotic Wildlife Level Z19In Africa,ostriches and zebras often feed together and use their combined sensory strengths to help keep each other safe from predators.Ostriches have good eyesight,and zebras have excellent hearing.Together,the two species have a much better chance of detecting a stalking lion or other predator on the prowl than they do alone,which helps them get a head start on escaping to safety.Africas impalas and baboons have a similar relationship.Impalas have superb hearing,sight,and sense of smell.If they detect danger first,their alert body language and horn shaking warn the baboons to beware.The baboons then sound the alarm,using their loud screams and intimidating teeth to scare predators away.AfricaIN D I A N O CE A NAT L A N T IC O CE A NGroups of ostriches and zebras often feed together and warn each other if they detect approaching predators.EuropeSymbiotic Wildlife Level Z116Hitching a RideMost small fish wisely keep their distance from sharks.A slender fish called a remora,though,does everything it can to get up close and personal with sharks.In fact,each remora has a flat,ribbed disc on the top of its head that functions as a suction cup to help the fish attach itself to the underside of a shark.Remoras are capable of swimming on their own,and they often do,but hitching a ride on a shark or other large creature is sometimes just an easier and more efficient way to get around.Once attached,a remora goes everywhere the shark hunts and feeds,eating any scraps of food that escape the sharks powerful jaws.The remoras provide a service,too,consuming
