Your Job Your Steps - The NSTA Website is …static.nsta.org/extras/forensics/1A-1C.pp32-41.pdf ·...
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Name Date 32 National Science Teachers Association Section 2: Training in Forensic Techniques Your Job In groups, examine antlers and horns at lab stations set up by your teacher. Show how each horn or antler at the station is unique through your descrip- tions, measurements, and drawings. Exchange your wrien analysis with an- other group’s and check the accuracy of their analysis by comparing it with the antler or horn they observed. Finally, determine the species of the head- gear using the Animal Headgear Information Cards that your teacher will give you aſter you have analyzed the antlers/horns at at least three stations. Your Steps 1. Go to your assigned lab station. Choose a member of the group to be a recorder. The recorder, with the group’s help, writes down the following on a half-sheet of paper—your “observation sheet.” Note: Do not record the antler or horn number that your teacher has assigned to the lab sta- tion on your observation sheet. Make a key with this information on a separate piece of paper. Names of people in the group. Qualitative data (You want other students to be able to read your observations and identify which specimen you are describing.) Write a description of the antler/horn. Draw the design and shape of the antler/horn. Quantitative data Make a measurement of the antler/horn. Count something on the antler/ horn (be sure to write down what it is that you have counted). Give size comparisons or ratios between parts on the antler/horn (example: ___________ is two times as long as _____________). 2. Visit at least three lab stations. Use a new sheet of paper at each new sta- tion. When finished, give your wrien observations to the teacher. • • • Handout 1-A Antlers and Horns: Student Lab Investigation Copyright © 2008 by the National Science Teachers Association. All rights reserved.
Transcript of Your Job Your Steps - The NSTA Website is …static.nsta.org/extras/forensics/1A-1C.pp32-41.pdf ·...
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32 National Science Teachers Association
Section 2: Training in Forensic Techniques
Your JobIngroups,examineantlersandhornsatlabstationssetupbyyourteacher.Showhoweachhornorantleratthestationisuniquethroughyourdescrip-tions,measurements,anddrawings.Exchangeyourwrittenanalysiswithan-othergroup’sandchecktheaccuracyoftheiranalysisbycomparingitwiththeantlerorhorntheyobserved.Finally,determinethespeciesofthehead-gearusing theAnimalHeadgear InformationCards thatyour teacherwillgiveyouafteryouhaveanalyzedtheantlers/hornsatatleastthreestations.
Your Steps
1. Gotoyourassignedlabstation.Chooseamemberofthegrouptobearecorder.Therecorder,withthegroup’shelp,writesdownthefollowingonahalf-sheetofpaper—your“observationsheet.”Note:Donotrecordtheantlerorhornnumberthatyourteacherhasassignedtothelabsta-tiononyourobservationsheet.Makeakeywiththisinformationonaseparatepieceofpaper.
Namesofpeopleinthegroup.Qualitativedata(Youwantotherstudentstobeabletoreadyourobservationsandidentifywhichspecimenyouaredescribing.)Writeadescriptionoftheantler/horn.Drawthedesignandshapeoftheantler/horn.
QuantitativedataMakeameasurementoftheantler/horn.Countsomethingontheantler/horn(besuretowritedownwhatitisthatyouhavecounted).Givesizecomparisonsorratiosbetweenpartsontheantler/horn(example:___________istwotimesaslongas_____________).
2. Visitatleastthreelabstations.Useanewsheetofpaperateachnewsta-tion.Whenfinished,giveyourwrittenobservationstotheteacher.
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Handout 1-A
Antlers and Horns:
Student Lab Investig
ation
Copyright © 2008 by the National Science Teachers Association. All rights reserved.
33Using Forensics: Wildlife Crime Scene!
Section 2: Training in Forensic Techniques
Handout 1-A
Antlers and Horns:
Student Lab Investig
ation
3. Your teacher will pass out the observations, making sure that groupsdonotget theirown.Read thewrittenobservationsofanothergroupandfindthespecimendescribed.Checkforaccuracyofallpartsoftheobservations. Write the specimen number on the top of the matchingobservations.
4. Returnthepaperstothegrouprecordersforthemtocheck.
5. Get a set of “Animal Headgear” information cards. Working in yourgroups,determinethespeciesforeachantlerandhorn.Recordyourde-cisionsinatwo-columntable(columnone:labstationnumber;columntwo:species).
6. Discussorwriteanswerstothefollowingquestions:
What Did You Discover About Antlers and Horns?
1. Whichwaseasier—writingadescriptiveobservationof thespecimensorcheckingtheaccuracyofanothergroup’sobservations?Why?
2. Whenyouwroteyourdescriptions,whichantler/hornwastheeasiesttodescribe?Why?Whichwasthehardest?Why?
3. Whenyoucheckedtheaccuracyofotherobservations,whichdescrip-tionwaseasiesttomatchwiththespecimen?Why?Whichwashardesttomatch?Why?
4. Whichtypeof informationwasmosthelpful inmatchingthedescrip-tion to the correct antler or horn:writtenword description, drawing,measurement,orcounts?Why?
5. Howwouldtheseobservationskillsbeimportantforsolvingawildlifecrime?
6. ReadyourcommentsonantlersandhornsinyourInvestigatorNotebook(What do I know…, What do I want to know…).Nowanswerthisquestion:What have I learned about antlers and horns?
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34 National Science Teachers Association
Handout 1-A
Antlers and Horns:
Student Lab Investig
ation
One person claims a new species has horns and someone else says it has antlers. How could they find the correct answer by observing the animal for a year?When would a female deer choose to mate with a male who is not the strongest and does not have the largest antlers or horns? Defend your answer.How does testosterone affect changes in both antler growth and male behavior?
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Section 2: Training in Forensic Techniques
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35Using Forensics: Wildlife Crime Scene!
Section 2: Training in Forensic Techniques
Name Date
Public Demand For Antlers and HornsTheantlersandhornsofmanydif-ferent animals across the globe arepopular both for their ornamentalbeauty and their perceived medici-nal value. The demand for theseantlersandhornshas fueled illegalhuntingandthetrafficking(buyingandselling)of these items. InsomecountriesintheMiddleEast,rhinoc-eroshornsarestillusedtomakedag-gerhandles.Groundintoapowder,rhinohorn isprescribed to treat fe-versintraditionalChinesemedicinein parts of the world today (LWC2006). Pieces of elk antler are soldillegally as an aphrodisiac (a foodordrug thatpeoplebelievearousessexualdesire),pricedashighassev-eralhundred dollarsanounce.Themarket for this item has become aprobleminAmerica’snationalparks,where rangers have reported find-ingdead(obviouslykilled)elkwithsawed-offantlers(Harrell2006).
What Does the Forensic Scientist Need To Know?Forensic scientists are often sentitems made from animal parts thatwere collected in police seizures.Inorder todetermine ifacrimehasbeencommitted,scientistsmustfirstidentify fromwhichanimal theant-ler or horn came. Even a small por-
tionofthismaterialcanbeenoughtodeterminethespeciesoforigin.Thus,suchmaterialisvaluableevidenceinwildlifecrimeinvestigation.
Deerandelkcanonlybekilleddur-ingcertainseasons.Therefore,scien-tistsmustbeable to tell the seasonthe antler was taken. Federal lawstatesthatantlersinvelvet(skinthatallows the antler to grow) must betreated with formaldehyde tomakethe velvet useless for traditionalAsianmedicines.Sinceitisillegaltohaveuntreatedvelvetantlers,scien-tistsmust runchemical tests tode-termine if formaldehyde treatmenthasbeendone.
Anatomy of Antlers And Horns
What animals have horns? Bighorn sheep, white sheep, moun-taingoats,bison,muskox,Americanpronghorn.
What are horns?Hornsareapermanentpartof theanimal’sskullandhavethreelayers(Figure1.1).Theinnerlayerextendsup from the skull as a bony core(Figure 1.2). It is covered by a thinlayerofblood-vessel-richtissuethatsuppliesbloodtotheouterlayerofthe horn, called the sheath. This
Handout 1-B
Specialized Headgear
:
Antlers and Horns
Copyright © 2008 by the National Science Teachers Association. All rights reserved.
36 National Science Teachers Association
thirdlayerismadeofkeratin,apro-tein that is also in fingernails andhair.Thesheathcontinues togrowthroughout theanimal’s lifeand iswhat people are referring to whentheyusethetermhorn(Figure1.3).
A: CoreB: SheathC: Keratin
Skull showing the bony core.
Outer keratin layer—the “horn” as we know it.
Handout 1-B
Specialized Headgear
:
Antlers and Horns
1.1
1.2
1.3
A
B
C
Section 2: Training in Forensic Techniques
Bothmalesandfemaleshavehorns,though the females’ are usuallysmaller.Hornsarenot shedexceptinAmericanpronghorns,whoshedthekeratinsheathonceeachyear.
What animals have antlers?White-taildeer,muledeer,elk,cari-bou,moose
What are antlers?Antlers grow from the skull (Figure1.4),andareshedonceeachyear.Theyare made of bone that grows fromtwodisc-shapedbumpsontheskull,called pedicles. During the monthswhen the antler is growing, the softcartilage is covered by blood-vessel-richskincalledvelvet.Whentheant-lerisfinishedgrowing,thistissuedies,thecartilagehardenstoboneandthevelvetfallsoff.Inallbutonespecies,thecaribou,onlymalesgrowantlers.Both sexes of caribou have antlers,thoughthefemales’aresmaller.
How big do antlers and horns grow?Thesizeofamale’santlersorhornstells a story. To grow large antlersor horns, a male must be healthyandwellfed—andstrongenoughtocarry theweightof this specializedheadgear. Elk antlers can weigh upto 25–40 pounds (11–18 kg). Malebighorn sheep horns can weigh asmuch as 30 pounds (14 kg). That is
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37Using Forensics: Wildlife Crime Scene!
Section 2: Training in Forensic Techniques
more that the weight of all otherbonesinhisbody!
What’s the Purpose of Antlers and Horns?Rutting (mating) season is the onetime during the year that males
AntlerA: Base—the raised rounded end of the main beam that is attached to the skull.B: Main beam—the part of the antler that grows from the base and supports the branching tines (points).C: Pedicle—disc-shaped bumps of bone on the skull from which antlers grow.
D: Prong or Tine—a point on an antler that is at least 1 inch long and longer than it is wide.E: Velvet—layer of blood-vessel-rich skin that covers the outside of a growing antler and supplies it with blood.
Handout 1-B
Specialized Headgear
:
Antlers and Horns
What are anatomical differences between antlers and horns?If an animal has antlers or horns, it must be a male. Agree or disagree. Defend your answer. An animal has to be killed to get its antlers or horns. Agree or disagree. Defend your answer.
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1.4
B
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DE
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gatherwiththefemaleherds.Dramaunfoldsasthemalesbattleeachotherwiththeirhornsandantlersforter-ritoryclosesttothefemales.Holdingonto this choice spot means a malehas more chances of mating witha female when she is ready. Eventhough the stronger, larger males
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Handout 1-B
Specialized Headgear
:
Antlers and Horns
stay busy chasing the other malesawayfromthefemales, theydonothave exclusive access. Females willmate with other males if the larger
male’s attention is distracted or ifa less dominant male is closer andmoreconvenienttothefemale.
Section 2: Training in Forensic Techniques
Harrell,A.2006.Point Reyes (California) Light.Parkrangersareafterelkantlerpoacherswhoselltheaphrodisiactoblack-marketshopsinChinatown.March2.
LewaWidlifeConservancy(LWC).2006.Usesofrhinohorn.www.lewa.org/rhino-horn-uses.php
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39Using Forensics: Wildlife Crime Scene!
Section 2: Training in Forensic Techniques
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Howcanmalesgrowhugeantlersinjust a few months? Why do antlersalwaysbegingrowinginthespring,lose theirvelvet in the fall,and falloff the male’s head in the winter?Whydonewantlersbegingrowingassoonasthefull-grownantlersfalloff? The answer to all these ques-tionsis…hormones,hormones,andmorehormones!
Antlers in the Spring to Mid-SummerSpringsignals thestartofnewant-lers. Soft layers of cartilage, grow-ing from the pedicle on the head,are covered by velvet (Figure 1.5).This thin layer of living tissue isfilled with blood vessels. Antlersgrow rapidly—moose antlers, for
examplecangrowuptooneinchaday. Although antlers can be dam-aged during this growing stage,the velvet provides some protec-tion while supplying blood to thegrowingtissue.
Why do the antlers grow? Anincrease indaylighttriggersthebodytomakehighlevelsofthemalehormonetestosterone.Thishormonestimulatesthegrowthofantlers.
Antlers in Late SummerAntlers begin to harden into boneandthevelvetbeginstofalloff.Thisiswhenmales canbe seen rubbingtheir antlers against trees to shedtheirvelvet(Figure1.6).
Deer with velvet antlers. Elk rubbing velvet strips on tree.
Handout 1-C
Antlers Through the
Seasons
1.61.5
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40 National Science Teachers Association
Why do the antlers stop growing?Bloodstopsflowingthroughthevel-vettotheantlers,causingthelivingtissuetodie.Theantlersstopgrow-ing, and change from soft cartilagetohardbone.
Antlers in Early FallThe antlers, cleaned of all velvet,are marked with grooves and ridg-es where blood vessels once lay.Theantlersarefirmlyattachedtothepedicleontheanimal’sskull.Thisisthe season of rut, when males usetheirantlerstobattlefortheterritoryclosesttothefemales.Claiminganddefending thisprime locationgivesthemmorechancestomate.
Why do the antlers remain in place?Testosterone remains high in earlyfall.Thiskeepstheantlersfirmlyat-tachedtotheskull.Italsoaffectsthemale’s behavior during the ruttingseason.Malesbecomemoreaggres-siveandwillingtofightforterritorynexttothefemales(Figure1.7).
Antlers in Late Fall Through Early WinterRut and mating season ends. Themales stop battling for territory,leave the females, and go off ontheirown.
Handout 1-C
Antlers Through the
Seasons
Two male elk fighting.
1.7
Section 2: Training in Forensic Techniques
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41Using Forensics: Wildlife Crime Scene!
Section 2: Training in Forensic Techniques
Why do males stop battling? Testosterone levels begin to drop,and so does the male’s aggressivematingbehavior.
Antlers in Late WinterAntlers falloff (areshed).Likekidswiggling loose teeth, males can beseenrubbingpartiallyattachedant-lersontrees.Itisnotunusualtoseea male with one antler hanging ormissing(Figure1.8).Inafewmonthsthecyclewillbeginagainasanewsetofantlersbeginstogrow.
Why do antlers fall off?Testosteronelevelsdroptotheirlow-estpoints, causing theantler tode-tachfromthepedicle.
Deer with one antler.
1.8
Handout 1-C
Antlers Through the
Seasons
Copyright © 2008 by the National Science Teachers Association. All rights reserved.
