Class ReptiliaClass ReptiliaChapter 20Chapter 20

Class ReptiliaClass Reptilia Reptilia - to creepReptilia - to creep

Turtles, crocodiles, lizards, Turtles, crocodiles, lizards, snakes, worm lizards, and snakes, worm lizards, and tuataranstuatarans

Class ReptiliaClass Reptilia First vertebrates to have First vertebrates to have

amniotic eggsamniotic eggs• Extraembryonic membranesExtraembryonic membranes

Protect the embryo from desiccationProtect the embryo from desiccation AlbumenAlbumen

• CushionsCushions• Moisturizes Moisturizes • Food sourceFood source

YolkYolk - supplies food - supplies food

Class ReptiliaClass Reptilia Other adaptations Other adaptations

for landfor land• Impervious skinImpervious skin

Keratin epidermal scalesKeratin epidermal scales

• Horny talesHorny tales• Water conserving Water conserving

kidneyskidneys• Enlarged lungsEnlarged lungs

Class ReptiliaClass Reptilia• Subclass Anapsida – lack Subclass Anapsida – lack

openings in the templeopenings in the temple TurtlesTurtles

• Subclass DiapsidaSubclass Diapsida Lower and upper openings Lower and upper openings

in the temporal region of the in the temporal region of the skullskull

Snakes, lizards, and Snakes, lizards, and tuatarastuataras

• Subclass Synapsida – Subclass Synapsida – single dorsal opening in single dorsal opening in the temporal region of the the temporal region of the skullskull

Class ReptiliaClass Reptilia Characteristics of reptilesCharacteristics of reptiles

Skull with one surfaceSkull with one surface Respiration by lungsRespiration by lungs Metanephric kidneysMetanephric kidneys Internal fertilizationInternal fertilization Amniotic eggsAmniotic eggs Very dry skin with Very dry skin with

keratinized scaleskeratinized scales 17 orders of Reptilia17 orders of Reptilia 4 Living orders of Reptilia4 Living orders of Reptilia

Class ReptiliaClass Reptilia

Order TestudinesOrder Testudines Tortoise and turtlesTortoise and turtles 225 Species of turtles225 Species of turtles

• Bony shellBony shell• Limbs from internal ribsLimbs from internal ribs• Keratinized beakKeratinized beak

Class ReptiliaClass Reptilia

• CarapaceCarapace - dorsal - dorsal portion of shellportion of shell

• PlastronPlastron - ventral portion - ventral portion of shellof shell

North American box turtle North American box turtle has hingeshas hinges

• Eight cervical vertebraeEight cervical vertebrae

Class ReptiliaClass Reptilia

• Long Life spanLong Life span 14 or more years14 or more years Up to 100 yearsUp to 100 years Sexual maturity Sexual maturity

seven or eight seven or eight yearsyears

Class ReptiliaClass Reptilia OviparousOviparous

Nest contain 5 - 100 eggsNest contain 5 - 100 eggs Development lasts 4 Development lasts 4

weeks to one yearweeks to one year Independent youngIndependent young Sea turtle conservation Sea turtle conservation

controversycontroversy

Class ReptiliaClass Reptilia Order RhynchocephaliaOrder Rhynchocephalia

Snout headSnout head• 2 living species of 2 living species of

TuatarasTuataras• BurrowBurrow• Endangered speciesEndangered species

Lizard-like reptilesLizard-like reptiles• Virtually unchanged from Virtually unchanged from

extinct membersextinct members Tooth arrangement is Tooth arrangement is

the distinguishing factorthe distinguishing factor

Class ReptiliaClass Reptilia OviparousOviparous

Share Share underground underground nesting burrows nesting burrows with ground-with ground-seeking sea birdsseeking sea birds

Venture out of the Venture out of the burrow at dawn burrow at dawn and dusk for and dusk for feedingfeeding

Class ReptiliaClass Reptilia Order SquamataOrder Squamata

Three subordersThree suborders• Suborder Sauria - the lizardsSuborder Sauria - the lizards• Suborder Serpentes - the snakesSuborder Serpentes - the snakes• Suborder Amphisbaenia - worm Suborder Amphisbaenia - worm

lizards lizards

Class ReptiliaClass Reptilia Lizards Lizards

3,300 species3,300 species Two pairs of limbs Two pairs of limbs Upper and lower jaws Upper and lower jaws

uniteunite Vary in length Vary in length

• Few centimeters up to 3 mFew centimeters up to 3 m

Class ReptiliaClass Reptilia HabitatHabitat

• Land Dwellers Land Dwellers • BurrowersBurrowers• Tree DwellersTree Dwellers

ReproductionReproduction• Most are oviparousMost are oviparous• Some are viviparous or Some are viviparous or

ovoviviparous ovoviviparous

Class ReptiliaClass Reptilia GeckoGecko

HabitatHabitat• SemitropicalSemitropical• ClimbersClimbers

Adhesion disks aidAdhesion disks aid NocturnalNocturnal Clicking vocalizationClicking vocalization

Class ReptiliaClass Reptilia

IguanaIguana Thick BodiesThick Bodies Short necksShort necks Distinct HeadsDistinct Heads

• Marine iguanaMarine iguana• Flying iguanaFlying iguana

Can fly 30 metersCan fly 30 meters

Class ReptiliaClass Reptilia Chamelions - Group of Chamelions - Group of

IguanasIguanas CharacteristicsCharacteristics

• Live in Africa and IndiaLive in Africa and India• Arboreal habitatArboreal habitat• Long, sticky tongueLong, sticky tongue• Change colorChange color

LightLight TemperatureTemperature BehaviorBehavior

Class ReptiliaClass Reptilia Gila Monster and Gila Monster and

Mexican Beaded LizardMexican Beaded Lizard• Venomous lizardVenomous lizard• Southwestern North Southwestern North

AmericaAmerica• Not fatal to humansNot fatal to humans

Class ReptiliaClass Reptilia Suborder - SerpentesSuborder - Serpentes

SnakesSnakes• 2,300 Species2,300 Species

300 are venomous300 are venomous 30,000 - 40,000 humans die each 30,000 - 40,000 humans die each

yearyear• Most occur in Southeast AsiaMost occur in Southeast Asia• < 100 Occur in the U.S. < 100 Occur in the U.S.

Class ReptiliaClass Reptilia CharacteristicsCharacteristics

Lack limbsLack limbs Up to 200 VertebraeUp to 200 Vertebrae Skull AdaptationsSkull Adaptations

• Movable upper jaw Movable upper jaw • Each jaw moves independentlyEach jaw moves independently

Class ReptiliaClass Reptilia

AdaptationsAdaptations• Differences in eye Differences in eye

focusingfocusing• Loss of left lungLoss of left lung• Displacement of Displacement of

GallbladderGallbladder Right KidneyRight Kidney GonadsGonads

Class ReptiliaClass Reptilia ReproductionReproduction

• OviparousOviparous• Live birthLive birth

BoasBoas Garter snakesGarter snakes

Age of snakesAge of snakes• 135 million years 135 million years

oldold• Possible relation to Possible relation to

caecilianscaecilians

ReptiliaReptilia Suborder AmphisbaeniaSuborder Amphisbaenia

Double walk Double walk Worm LizardsWorm Lizards

• 135 Species135 Species• HabitatHabitat

Specialized burrowersSpecialized burrowers Africa, South America, Caribbean, Africa, South America, Caribbean,

and Mideastand Mideast

ReptiliaReptilia CharacteristicsCharacteristics

LeglessLegless Wedge shaped headWedge shaped head Single median tooth in Single median tooth in

upper jawupper jaw Can move forward or Can move forward or

backwardbackward

ReptiliaReptilia Order CrocodiliaOrder Crocodilia

Greek - lizardGreek - lizard 21 species21 species Crocodiles, alligators, Crocodiles, alligators,

gavials, and caimansgavials, and caimans Have existed for 170 Have existed for 170

million yearsmillion years

ReptiliaReptilia

ReptiliaReptilia

ReptiliaReptilia Snout is elongatedSnout is elongated Nostrils at the anterior end to Nostrils at the anterior end to

help with breathing while help with breathing while mostly submergedmostly submerged

Breathe and inhale water at Breathe and inhale water at the same timethe same time

ReptiliaReptilia

TailTail Muscular, elongated, and Muscular, elongated, and

laterally compressedlaterally compressed Used for swimming, attacking Used for swimming, attacking

prey, and maneuversprey, and maneuvers

ReptiliaReptilia

TeethTeeth Laterally compressed teethLaterally compressed teeth Thrashing motion of captureThrashing motion of capture Swallow food wholeSwallow food whole Death roll Death roll

StomachStomach Gizzard-likeGizzard-like Swallow rocks and other Swallow rocks and other

objectsobjects

ReptiliaReptilia ReproductionReproduction

OviparousOviparous Parental Care Parental Care

resembles that of birdsresembles that of birds Nesting and parental Nesting and parental

care can be traced to care can be traced to common ancestor of common ancestor of both groupsboth groups

ReptiliaReptilia External StructuresExternal Structures

Skin Skin • No respiratory functionNo respiratory function• Thick, dry, and keratinized scalesThick, dry, and keratinized scales• Shedding of the scales is called Shedding of the scales is called ecdysisecdysis• Pheromones are secretedPheromones are secreted• Cryptic, Aposematic, and mimicry Cryptic, Aposematic, and mimicry

coloration coloration

ReptiliaReptilia SupportSupport

Skeleton resembles amphibian formSkeleton resembles amphibian form Skull is elongatedSkull is elongated Secondary palateSecondary palate IncreaseIncrease in cervical vertebrae in cervical vertebrae

• Atlas and axis increase head Atlas and axis increase head movementmovement

Ribs can be highly modifiedRibs can be highly modified• CobraCobra• Flying lizardsFlying lizards

AutotomyAutotomy - loss of a tail - loss of a tail

ReptiliaReptilia MovementMovement

Prehistoric ReptilesPrehistoric Reptiles• Many were bipedalMany were bipedal

ReptileReptile• TetrapodsTetrapods• Primitive reptiles move like Primitive reptiles move like

salamanderssalamanders• Higher than most Higher than most

amphibiansamphibians

ReptiliaReptilia Nutrition and DigestionNutrition and Digestion

CarnivoresCarnivores TongueTongue

• Turtles and crocodiles are Turtles and crocodiles are nonprotrusiblenonprotrusible

• Lizards and anurans have Lizards and anurans have sticky tonguessticky tongues

May exceed the lizards May exceed the lizards lengthlength

ReptiliaReptilia Snakes Snakes

Glottis is far forward to allow Glottis is far forward to allow for breathingfor breathing

Vipers have hollow fangs that Vipers have hollow fangs that are hinged on the maxillaryare hinged on the maxillary

Coral, sea, and cobra snakes Coral, sea, and cobra snakes rigid fangsrigid fangs

Some cobras can “spit”Some cobras can “spit” Venom glands are modified Venom glands are modified

salivary glandssalivary glands

ReptiliaReptilia Body RegulationBody Regulation

Gas ExchangeGas Exchange• Three chambered heartThree chambered heart• Sinous venosus is now a Sinous venosus is now a

pacemakerpacemaker

ReptiliaReptilia Low oxygenated blood Low oxygenated blood

from right atrium to from right atrium to ventricle ventricle

High oxygenated blood High oxygenated blood from lungs to ventricle to from lungs to ventricle to left atriumleft atrium

ReptiliaReptilia Gas exchangeGas exchange

Across respiratory Across respiratory surfacessurfaces

Partitioned into Partitioned into spongelike chambersspongelike chambers

Form a negative Form a negative pressure mechanism pressure mechanism for ventilationfor ventilation

ReptiliaReptilia Temperature RegulationTemperature Regulation

EctothermsEctotherms• Can survive (-2 to 41 Can survive (-2 to 41 ooC) C) • Need (25 to 37 Need (25 to 37 ooC) to liveC) to live

Behavior is used for Behavior is used for temperature regulationtemperature regulation

• Body orientationBody orientation• NocturnalNocturnal• PantingPanting• Blood diversionBlood diversion• Chormatophore dispersionChormatophore dispersion

ReptiliaReptilia Nervous and Sensory Nervous and Sensory

FunctionsFunctions• Cerebral hemisphere is larger Cerebral hemisphere is larger

than in Amphibiansthan in Amphibians Improved smellImproved smell

• Jacobson organJacobson organ• Snakes can smell with their Snakes can smell with their

tonguetongue Improved vision motor Improved vision motor

coordinationcoordination Ears detect vibrationsEars detect vibrations Snakes have heat sensitive pit Snakes have heat sensitive pit

organsorgans

ReptiliaReptilia Optic lobe and Cerebellum are Optic lobe and Cerebellum are

enlargedenlarged Increased visionIncreased vision More refined motor coordinationMore refined motor coordination

• Independent eye movementIndependent eye movement• Different fields of visionDifferent fields of vision• Dominant sense in most reptilesDominant sense in most reptiles• Colored visionColored vision

ReptiliaReptilia Excretion Excretion

• Kidneys have more Kidneys have more nephronsnephrons or blood filtering or blood filtering units (units (Metanephric kidneysMetanephric kidneys))

More blood flowMore blood flow Higher pressureHigher pressure

• Excrete uric acidExcrete uric acid Insoluble in waterInsoluble in water Can be stored as a pasteCan be stored as a paste

ReptiliaReptilia OsmoregulationOsmoregulation

Reabsorption of waterReabsorption of water Internal respiratory surfacesInternal respiratory surfaces Relatively impermeable Relatively impermeable

exposed skinexposed skin BehaviorBehavior

• NocturnalNocturnal• Avoidance of hot surfacesAvoidance of hot surfaces

Storage of water in lymphatic Storage of water in lymphatic spacesspaces

ReptiliaReptilia ReproductionReproduction

EggsEggs• Land dwelling is possibleLand dwelling is possible• Not completely independent of Not completely independent of

waterwater

ReptiliaReptilia Internal FertilizationInternal Fertilization

Egg shell forms afterEgg shell forms after Males have an intromittent Males have an intromittent

organorgan Sperm can be stored by the Sperm can be stored by the

femalefemale• Turtles 4 yearsTurtles 4 years• Snakes 6 yearsSnakes 6 years

ReptiliaReptilia Parthenogenesis Parthenogenesis

6 families of lizards6 families of lizards 1 family of snake1 family of snake Parental CareParental Care

• Eggs are usually abandonedEggs are usually abandoned• 100 species of reptiles take care of 100 species of reptiles take care of

their young their young American alligatorAmerican alligator Sex is temperature dependentSex is temperature dependent