reptiles and amphibians read - 7th Grade Sci · 2018-01-17 · All reptiles have a cloaca, a single...
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Reptiles and amphibians Name: _________________________________________ Class:__________ Date: ____________ Vocabulary Term Definition amniote Embryos are surrounded by a thin, protective membrane. asexual reproduction Reproduction involving only one individual. cloaca External opening that serves as the exit (and entrance) for the intestinal, reproductive, and urinary tracts. ectothermic Having an internal temperature that depends on the temperature of their environment. external fertilization Fertilization of the egg outside the body. internal fertilization Fertilization of the egg within the body of the female. What does this chameleon have in common with a snake? Though they are both reptiles and seem very different, chameleons and snakes actually share several traits. For example, they both have skin covered in scales and are cold-blooded animals. But notice the distinct eyes and "horns" on the chameleon. Snakes don't have these. And some chameleons have the ability to change color. Characteristics of Reptiles What reptiles can you name? Snakes, alligators, and crocodiles are all reptiles. Modern reptiles live on every continent except Antarctica. They range in size from the newly-discovered Jaragua Sphaero (a dwarf gecko), at 0.6 inches, to the saltwater crocodile, at up to 23 feet. There are four living orders of reptiles: • Squamata, which includes lizards, snakes, and amphisbaenids (or “worm-lizards”). • Crocodilia, which includes crocodiles, gharials, caimans, and alligators. • Testudines, which includes turtles and tortoises. • Sphenodontia, which includes tuatara. Traits of Reptiles Reptiles are tetrapods (four-legged) and ectothermic, meaning their internal temperature depends on the temperature of their environment. This is why you may see reptiles sunbathing as they use the energy from the sun to warm their bodies. Usually the sense organs of reptiles, like ears, are well developed, though snakes do not have external ears. All reptiles have advanced eyesight. Reptiles also have a sense of smell. Crocodilians, turtles, and tortoises smell like most other land vertebrates. But, some lizards, and all snakes, smell with their tongues, which is flicked out of the mouth to pick up scent molecules from the air. Reptiles also have several adaptations for living on land. They have a skin covered in scales to protect them from drying out. All reptiles have lungs to breathe air. Reptiles are also amniotes, which means their embryos are surrounded by a thin membrane. This membrane protects the embryo from the harsh conditions of living on land. Reptile eggs are also surrounded by a protective shell, which may be either flexible or inflexible. How Do Reptiles Reproduce?
Transcript of reptiles and amphibians read - 7th Grade Sci · 2018-01-17 · All reptiles have a cloaca, a single...
Reptiles and amphibians Name:_________________________________________Class:__________Date:____________Vocabulary
Term Definition
amniote Embryosaresurroundedbyathin,protectivemembrane.
asexual reproduction Reproductioninvolvingonlyoneindividual.
cloaca Externalopeningthatservesastheexit(andentrance)fortheintestinal,reproductive,andurinarytracts.
ectothermic Havinganinternaltemperaturethatdependsonthetemperatureoftheirenvironment.
external fertilization Fertilizationoftheeggoutsidethebody.
internal fertilization Fertilizationoftheeggwithinthebodyofthefemale.What does this chameleon have in common with a snake? Thoughtheyarebothreptilesandseemverydifferent,chameleonsandsnakesactuallyshareseveraltraits.Forexample,theybothhaveskincoveredinscalesandarecold-bloodedanimals.Butnoticethedistincteyesand"horns"onthechameleon.Snakesdon'thavethese.Andsomechameleonshavetheabilitytochangecolor.
Characteristics of Reptiles Whatreptilescanyouname?Snakes,alligators,andcrocodilesareallreptiles.ModernreptilesliveoneverycontinentexceptAntarctica.Theyrangeinsizefromthenewly-discoveredJaraguaSphaero(adwarfgecko),at0.6inches,tothesaltwatercrocodile,atupto23feet.Therearefourlivingordersofreptiles:
• Squamata,whichincludeslizards,snakes,andamphisbaenids(or“worm-lizards”).• Crocodilia,whichincludescrocodiles,gharials,caimans,andalligators.• Testudines,whichincludesturtlesandtortoises.• Sphenodontia,whichincludestuatara.
Traits of Reptiles Reptilesaretetrapods(four-legged)andectothermic,meaningtheirinternaltemperaturedependsonthetemperatureoftheirenvironment.Thisiswhyyoumayseereptilessunbathingastheyusetheenergyfromthesuntowarmtheirbodies.Usuallythesenseorgansofreptiles,likeears,arewelldeveloped,thoughsnakesdonothaveexternalears.Allreptileshaveadvancedeyesight.Reptilesalsohaveasenseofsmell.Crocodilians,turtles,andtortoisessmelllikemostotherlandvertebrates.But,somelizards,andallsnakes,smellwiththeirtongues,whichisflickedoutofthemouthtopickupscentmoleculesfromtheair.Reptilesalsohaveseveraladaptationsforlivingonland.Theyhaveaskincoveredinscalestoprotectthemfromdryingout.Allreptileshavelungstobreatheair.Reptilesarealsoamniotes,whichmeanstheirembryosaresurroundedbyathinmembrane.Thismembraneprotectstheembryofromtheharshconditionsoflivingonland.Reptileeggsarealsosurroundedbyaprotectiveshell,whichmaybeeitherflexibleorinflexible.How Do Reptiles Reproduce?
Mostreptilesreproducesexually,meaningtherearetwoparentsinvolved.Insomefamiliesoflizardsandonesnakefamily,however,asexualreproductionispossible.Thisiswhenonlyoneparentisinvolvedincreatingnewlife.Forexample,thegeckofemalescanmaketinyclonesofthemselveswithouttheaidofamale.Allreptileshaveacloaca,asingleexitandentranceforsperm,eggs,andwaste,locatedatthebaseofthetail.Mostreptileslayamnioticeggscoveredwithleatheryorhardshell.Theseeggscanbeplacedanywhereastheydon'thavetobeinamoistenvironment,liketheeggsofamphibians.However,notallspecieslayeggs,ascertainspeciesofsquamatescangivebirthtoliveyoung.Unliketheamphibians,therearenolarvalstagesofdevelopment.Theyoungreptileslooklikeminiatureversionsoftheadult.Theyoungreptilesaregenerallylefttofendforthemselves.However,somereptilesprovidecarefortheiryoung.Forexample,crocodilesandalligatorsmaydefendtheiryoungfrompredators.
What were the first land vertebrates? Amphibians!Inorderforwater-dwellinganimalstoadapttolifeonland,manynewadaptationshadtotakeplace.First,theyneededtobeabletobreatheairinsteadofobtainingoxygenfromwater.Andfinsdon'tworkwellaslegs!Theyneededtobeabletomovearoundwellonland.
Characteristics of Amphibians Whatgroupofanimalsbeginsitslifeinthewater,butthenspendsmostofitslifeonland?Amphibians!Amphibiansareagroupofvertebratesthathasadaptedtoliveinbothwaterandonland.Amphibianlarvaearebornandliveinwater,andtheybreatheusinggills.Theadultsliveonlandforpartofthetimeandbreatheboththroughtheirskinandwiththeirlungsastheirlungsarenotsufficienttoprovidethenecessaryamountofoxygen.Thereareapproximately6,000speciesofamphibians.Theyhavemanydifferentbodytypes,physiologies,andhabitats,rangingfromtropicaltosubarcticregions.Frogs,toads,salamanders,newts,andcaeciliansarealltypesofamphibians. How did Amphibians Adapt to Living on Land? Transitiontolifeonlandmeantsignificantchangestobothexternalandinternalfeatures.Inordertoliveonland,amphibiansreplacedgillswithanotherrespiratoryorgan,thelungs.Otheradaptationsinclude:
• Skinthatpreventslossofwater.• Eyelidsthatallowthemtoadapttovisionoutsideofthewater.• Aneardrumdevelopedtoseparatetheexternalearfromthemiddleear.• Atailthatdisappearsinadulthood(infrogsandtoads).
Classification of the Amphibians Likefish,amphibiansareectothermicvertebrates.TheybelongtotheclassAmphibia.Therearethreeorders:
• Urodela,containingsalamandersandnewts.• Anura,containingfrogsandtoads.• Apoda,containingcaecilians.
Where do Amphibians Live? Mostamphibiansliveinfreshwater,notsaltwater.Theirhabitatscanincludeareasclosetosprings,streams,rivers,lakes,swampsandponds.Theycanbefoundinmoistareasinforests,meadowsandmarshes.Amphibianscanbefoundalmostanywherethereisasourceoffreshwater.Althoughtherearenotruesaltwateramphibians,afewcanliveinbrackish(slightlysalty)water.Somespeciesdonotneedanywateratall,andseveralspecieshavealsoadaptedtoliveindrierenvironments.Mostamphibiansstillneedwatertolaytheireggs.
How do Amphibians Reproduce? Amphibiansreproducesexually.Thelifecycleofamphibianshappensinthefollowingstages:
1. EggStage:Amphibianeggsarefertilizedinanumberofways.Externalfertilization,employedbymostfrogsandtoads,involvesamalegrippingafemaleacrossherback,almostasifheissqueezingtheeggsoutofher.Themalereleasesspermoverthefemale'seggsastheyarelaid.Anothermethodisusedbysalamanders,wherebythemaledepositsapacketofspermontotheground.Thefemalethenpullsitintohercloaca,asingleopeningforherinternalorgansystems.Therefore,fertilizationoccursinternally.Bycontrast,caeciliansandtailedfrogsuseinternalfertilization,justlikereptiles,birds,andmammals.Themaledepositsspermdirectlyintothefemale'scloaca.
2. Larvalstage:Whentheegghatches,theorganismislegless,livesinwater,andbreatheswithgills,resemblingtheirevolutionaryancestors(fish).
3. Duringthelarvalstage,theamphibianslowlytransformsintoanadultbylosingitsgillsandgrowingfourlegs.Oncedevelopmentiscomplete,itcanliveonland.
Summary
• Reptilesarealsoamniotes,whichmeanstheirembryosaresurroundedbyathinmembrane.• Reptilestypicallyreproducesexuallyandlayeggs.• Amphibiansliveinbothwaterandonland;amphibianlarvaearebornandliveinwater,andthey
breatheusinggills.Theadultsliveonlandforpartofthetimeandbreatheboththroughtheirskinandwiththeirlungs.
• Adaptationsforlandinamphibiansincludeprotectiveskinandeyelidsthatallowthemtoadapttovisionoutsideofthewater.
Review
1. Namefourexamplesofreptiles.2. Whatisectothermic?3. Whatarethereptilianadaptationsforlifeonland?4. Comparedtotheamphibianegg,whatisspecialaboutthereptileegg?5. Listthreeadaptionsamphibianshaveforlifeonland?6. Listfourexamplesofamphibians.7. Howdoamphibiansreproduce?8. Describetheamphibianlarvalstage.Whatchangesoccurduringthisstage?
