Parasitic Species .:(\ r.l j , .::., ' :\-\ t(-( nima]s and plants have diff-erent ways of living. I ..-,: .; ISome -( specieslive at the expense of others. That is, they take their food and energr from other organisms on which they live. Such speciesare called "parasites."The specieson which they live are called their "hosts." One famous parasitic plant in the southern United States is called "Spanish moss." It hangs in long, Most parastticspecies are harn'tfulto their hosts delicate, gray lines from the branches of trees. Another well-known parasitic plant is mistletoe. It is a familiar O Mistletoeis a vinewith dark symbol of the Christmas seasono.Very few people know that the greenleaves and red berries. lt is oftenused as a Christmas pretty green and white mistletoe is really a parasitel decoratron, Animal parasitesare more fan-riliar.Fleas and ticks are animal parasites.Dogs € Thereare five Great Lakes, Lake serve as their hosts. The fleas and ticks live on rhe Huron,Lake Ontario, Lake Michigan, dogs'blood. They can also causedisease! LakeErie, and Lake Superior. They arelocated in the northernU.S., Fish have parasites alongthe borderwith Canada.They too. In America's Great Lakese, for example, an aresome of the largestlakes in the eel-like animal called a lamprey preys on fish. The lamprey has a wono. rotrnd mouth Iike a suction cupo, and a shalp tongue like a file. First, suct|oncup the lamprey usesits round mouth to attach itself to a fish. Then the lamprey uses its file-like tongue to drill into the fishs body and live .ji on the fishs body fluids. ExF :-.'i @ A suction cup is a round, Other fish parasites are strange animals called "isopods." They have ,+, hollowdevice used to apply suctronor attachone objectto oval bodies and many legs. Sometimes they live inside a fish's 2 Thr another. mouth. Other parasites may attack a fish's gillso. One of the oddest the parasites on fishes is the "remora." A fish itself, the remora has a suction tool on its head. \X/ith the suction tool, the remora attaches @ Gillsareorgans deep rn a fish's itself to the side of a shark. When the shark kills and eats throatwhich allow fish to breathein 3 Loc something, the remora eats bits and pieces the sharkt food. If water.They serve the same of int functionthat lungs do in mammals. too many remoras ride along with it, however, the shark may have trouble swimming! 4 In! coreTopicGuide E $wre Parasitescan live either on the inside or the outside of a host. The fust kind of parasite is especially dangerous. It can live, unseen and unsuspected, for a long time inside a host. Such internd parasites vaysof living. can kill an animal before anvone knows they are there! se of others. y from other :ies arecalled live are called thern United angs in long, mistletoe ies of trees. fmisltdu] c.|) lamprey [1#mpri] is a familiar isopod [disapdd] now that the 4. remora I16mara] wo*us ron Broro€v .s are animal fl / <s Iive on the attach ; fluid '/ host r internal r example, an "' organrsm I prey rmprey has a / species <ea file. First, r suction ish. Then the body and live aqgi!gr,! 1 Explainthe terms parasiteand host in your own words. s." They have nside a fish's 2 The articlementions several parasites. Name two of them,and describehow ofthe oddest they live. remora has a nora attaches ills and eats 3 Lookat the word internal in the passage.What do you think internal means Lark'sfood. If in this context? ark may have 4 In your own words,describe one problemthat parasitescan cause. LinguaForumil X-rays of Fossils .t :lr har-e t = :crhnirlue t ::nrcnsi<;nal (scientistswho ancientlife) used ptl.ott,ologists study :J.,\ t() lOOk I to fossilso have a problem. How could they study irn, r:eurs' skr without destroyingthe fossils?Sometimes, that was difficult. Fossilsare often found embedded in rock. The \c-n rinv fosr rock must be removedbefore the fossil can be seenand ::' ,nl rtrkS tI studied.And as the rock is removed,the fossil may get I aninta 'Was 't':r damaged. there a better, lesshazardous way to study :hrough X-ra fossils? \o one expe 'W'hen There was. X-rayswere discovered,they were g'hen the ani found to expose photographic plates. So, X-ray the microsco photographybegane. Norq it was possibleto see inside these images By studytngfossils, scientists can learnabout ancient antmals. something by passingX-rays through it and taking a rr'e could not "snapshot€"of the object. This was a great advancefor has come in t O Fossilsare bonesof longdead medicine. Now doctors could use X-rays to look inside a living animals. person'sbody o Thef irstX+ay machines were But paleontologists had a good use for X-ray pictures, too. Here was developedin'1913. the nondestructive tool they needed to study fossils! \With X-rays, O Snapshotis a photographyword it was no longer necessaryto "open up" a rock that had a fossil refeningto a picturetaken quickly inside. take an X-ray picture of the rock and seewhat appeared andcasually without planning. Just on the image! Ques t ions The results have been astonishing. Rocks in Germany for example, were fi.lled with fossils of "trilobites," ancient sea animals related to 1 Wha modern crabs and lobsters. X-rays showed the trilobites in great detail. Scientists were able to study the fossils closely without 2 Lool damaging them! mea The X-ray picrures were also beautiful. In fact, they had such a strange beauty that some of them went on display in a traveling 3 The show years ago. The X-ray images, then, were more than just tools help of science.Theywere art as well! 4 Expl coreToPicGuide E $xs X-rayshave been usedto srudy other fossils,too. Especiallyusefirl is a technique that usescomputers to turn X-ray pictures into three- dimensionalimages of fossils'insides. Paleontologists have used X- :ient life) used rays to look inside dinosaureggs and study the structure of study fossilso dinosaurs'skulls. les, that was I in rock. The Very tiny fossilsshow up clearly in X-ray imagesas well. In samples qt An embryois a babyof an anrmal yet, n be seen and from rocks that wereonce at the bottom of the sea,fossil embryoso that hasnot beenborn andis not yet fullydeveloped. fossil may get of sea animals - no bigger than grains of sand - have been found r way to study through X-ray studies. O Here,yef meansbut. No one expectedto find the embryosof ancientanimals, preserved <> trilobite :d, they were when the animal was just a little ball of cells.But with X-ray images, ltrdilabdit] s. So, X-ray the microscopicfossils became visible. And like the trilobite X-rays, to see inside theseimages Th.y show tiny yeto complex fossilsthat are beautifirl. fl wonosron Brolocv and taking a we could not hope to seeotherwise. They alsoshow how far biology Y cell .t advance for hascome in the lastroo years! ./ destroy nside a living z embed r' emDryo / expose / fossil too. Here was / hazardous Y microscopic With X-rays, / paleontologist t had a fossil / preserve i'hat appeared Y skull Ques t lons ; for example, passage rals related to 1 What is this mainlyabout? Summarize it in one sentence. bites in great ,sely without 2 Lookat the word embedded in the passage.What do you think embedded meansin this conte)d? y had such a in a traveling 3 The authorexplains how X-rayshelp in studyingfossils. List two waysthey han just tools help,and explainhow theydo so. 4 Explainhow X-raytechnology has advanced over the years. LinguaForum il Introduced Species rntrorluct I:uropeanr rhc urltl. - of the most f-amiliaranimals and plants in America did nor Qome \\-crccvcq Ulive there originally They were introduced there by humans, either by accident or intentionally So, we call them "introduced ( )thcr r'ou species." tirr cramp l n f r()( IUCCi Introduced species may arrive in many different ways. They may ( gc ride on imported wood, on ships, or even by airplane, and then get -.rn.rtle h.r. lr:con looseo in a new environment where they can reproduce and ncctl tt, tu multiply In many cases,they become very nurnerous because they have no natural enemies in their new home. \X/hen they become In nr.rnv c too numerous, the introduced speciescause many problems. -lhet Litcr .]t \1 .1\'\ t( ) Some introduced species are colorfirl and interesting. The ring- :-r, lml: necked pheasant, a beautiful game birdo, was introduced to 'nt Zebramussels often cover underwater America from Asia. Other introduced speciesin America have been ptpes,causing great damage. there so long that we no longer think of them as introduced species. The common dandelion, for example, is an introduced species.So is O To get loose means to escape or the honeybee, which helps us by making honey and spreading to be set free. pollen to plants. @ A game bird rs a bird that is But other introduced species are annoying and even dangerous. The hunted for sport. zebra mussel, for example, was introduced to American waters by ships from overseas.Known for its distinctive striped shell, the zebra mussel lives in big colonies that are hard to remove from pipes. Getting rid of them takes much time, effort, and money Americans wish the zebra mussel had staved overseas! Q;estrons America aiso would like to get rid of the g,?sy morh. It attacks 1 W many kinds of trees. The gypsy moth was released by accident in ar '\X/ith Boston during the mid-r9th century no natural enemies to stop it, the g,psy moth has spread through the northeastern United States,damaging and killing countless trees.