animal apbio

Chapter 22Chapter 22

The Animal The Animal KingdomKingdom

Chapter 22 2

What Is an Animal?What Is an Animal?

Multicellular heterotrophsMulticellular heterotrophs

Lack a cell wallLack a cell wall

Motile during some stage in lifeMotile during some stage in life

Able to respond rapidly to external stimuliAble to respond rapidly to external stimuli

Able to reproduce sexuallyAble to reproduce sexually

Chapter 22 3 Animal EvolutionAnimal Evolution

Most animal phyla currently populating Most animal phyla currently populating the Earth were present by the Cambrian the Earth were present by the Cambrian period period (544 million years ago)(544 million years ago)

The scarcity of pre-Cambrian fossils led The scarcity of pre-Cambrian fossils led systematists to search for clues about systematists to search for clues about the evolutionary history of animals by the evolutionary history of animals by examining features ofexamining features of• AnatomyAnatomy• Embryological developmentEmbryological development• DNA sequencesDNA sequences

Chapter 22 4 Animal EvolutionAnimal Evolution

Certain features represent evolutionary Certain features represent evolutionary milestonesmilestones• The appearance of tissuesThe appearance of tissues• The appearance of body symmetryThe appearance of body symmetry• Protostome and deuterostome Protostome and deuterostome

developmentdevelopment

These features mark major branching These features mark major branching points on the animal evolutionary treepoints on the animal evolutionary tree

Chapter 22 5 The Appearance of Body SymmetryThe Appearance of Body Symmetry

Symmetrical animals have an upper Symmetrical animals have an upper (dorsal) surface and a lower (ventral) (dorsal) surface and a lower (ventral) surfacesurface

Animals with tissues exhibit either radial Animals with tissues exhibit either radial or bilateral symmetryor bilateral symmetry

Animals with Animals with radialradial symmetrysymmetry can be can be divided into roughly equal halves by any divided into roughly equal halves by any plane that passes through the central plane that passes through the central axisaxis

Chapter 22 6

Body Symmetry and CephalizationBody Symmetry and CephalizationCentral AxisCentral Axis

A Radial PlaneA Radial Plane

Another Radial PlaneAnother Radial Plane

(a)(a) RadialRadialSymmetry Symmetry

Sagittal PlaneSagittal Plane

AnteriorAnterior

PosteriorPosterior(b)(b) BilateralBilateralSymmetry Symmetry

Chapter 22 7 Body CavitiesBody Cavities

AcoelomateAcoelomate animals lack a body cavity animals lack a body cavity• e.g. flatwormse.g. flatworms

Chapter 22 8

Body Cavities:Body Cavities:The AcoelomatesThe Acoelomates

DigestiveDigestiveCavityCavity

DigestiveDigestiveLiningLiningSolidSolid

TissueTissue

Body Body WallWall

No cavity between No cavity between body wall & body wall &

digestive tractdigestive tract

CnidariaCnidaria


PseudocoelomatePseudocoelomate animals possess a animals possess a pseudocoelompseudocoelom (a fluid-filled body cavity (a fluid-filled body cavity that is that is notnot completely lined with completely lined with mesoderm)mesoderm)• e.g. nematodes (roundworms)e.g. nematodes (roundworms)

Chapter 22 10

Body Cavities:Body Cavities:The PseudocoelomatesThe Pseudocoelomates

Digestive CavityDigestive Cavity

Digestive TractDigestive Tract

PseudocoelomPseudocoelom

Body WallBody Wall

Body cavity Body cavity partially lined with partially lined with

mesodermmesoderm

Partial LiningPartial Lining

NematodaNematoda


CoelomateCoelomate animals possess a animals possess a coelomcoelom (a (a fluid-filled body cavity that is fluid-filled body cavity that is completely lined with mesoderm)completely lined with mesoderm)• e.g. annelids, arthropods, mollusks, e.g. annelids, arthropods, mollusks,

echinoderms, chordatesechinoderms, chordates

Chapter 22 12

Body Cavities:Body Cavities:The True CoelomatesThe True Coelomates

Digestive CavityDigestive Cavity

Digestive TractDigestive Tract

CoelomCoelom

Body WallBody Wall

Body cavity Body cavity completely lined completely lined with mesodermwith mesoderm

Complete LiningComplete Lining

AnnelidaAnnelida

Chapter 22 13 Embryological DevelopmentEmbryological Development

Bilateral animals can be divided into two main Bilateral animals can be divided into two main groups based on embryological developmentgroups based on embryological development

ProtostomesProtostomes• Body cavity forms within a space between the Body cavity forms within a space between the

body wall and the digestive cavitybody wall and the digestive cavity• e.g. nematodes, arthropods, flatworms, annelids, e.g. nematodes, arthropods, flatworms, annelids,

mollusksmollusks

DeuterostomesDeuterostomes• Body cavity forms as an outgrowth of the Body cavity forms as an outgrowth of the

digestive cavitydigestive cavity• e.g. echinoderms, chordatese.g. echinoderms, chordates

Chapter 22 14

Evolutionary TreeEvolutionary Treeof Major Animal Phylaof Major Animal Phyla

Porife

ra

Porife

ra

No trueNo truetissuestissues

TrueTruetissuestissues

2 tissue2 tissuelayers; radiallayers; radial

symmetrysymmetry

Ctenop

hora

Ctenop

hora

Cnidar

ia

Cnidar

ia

3 tissue3 tissuelayers; bilaterallayers; bilateral

symmetrysymmetry

Platyh

elmint

hes

Platyh

elmint

hes

No bodyNo bodycavitycavity Body cavityBody cavity

PseudocoelPseudocoel

Nemato

da

Nemato

da

Rotife

ra

Rotife

ra

CoelomCoelom

ProtostomeProtostomedevelopmentdevelopment

Anneli

da

Anneli

da

Mollus

ca

Mollus

ca

Insec

ta

Insec

ta

DeuterostomeDeuterostomedevelopmentdevelopment

Mammali

a

Mammali

a

Echino

-

Echino

-de

rmata

derm

ata

Chapter 22 15

The Invertebrate Phyla:The Invertebrate Phyla:PoriferaPorifera

Phylum Porifera: the spongesPhylum Porifera: the sponges• Simple single-celled organisms living togetherSimple single-celled organisms living together• Low specialization of cells; no tissue levelLow specialization of cells; no tissue level• Asymmetrical ::::: Reproduce by buddingAsymmetrical ::::: Reproduce by budding

Three major types of cellsThree major types of cells• Epithelial cellsEpithelial cells (cover outer body surface) (cover outer body surface)

– Some are modified into Some are modified into pore cellspore cells (regulate flow of water (regulate flow of water through pores)through pores)

• Collar cellsCollar cells (flagellated cells that maintain water (flagellated cells that maintain water flow through the sponge)flow through the sponge)• Amoeboid cellsAmoeboid cells (motile cells that digest and (motile cells that digest and

distribute nutrients, produce reproductive cells, distribute nutrients, produce reproductive cells, and secrete and secrete spiculesspicules))

Chapter 22 16

The Body The Body Plan of Plan of SpongesSponges

OsculumOsculumEpithelialEpithelialCellCell

SpiculesSpiculesAmoeboidAmoeboidCellsCells

PorePoreCellCell

CollarCollarCellCell

PorePore

Water FlowWater Flow

Chapter 22 17

The Invertebrate Phyla: CnidariaThe Invertebrate Phyla: Cnidaria

Phylum Cnidaria: the hydra, anemones, & Phylum Cnidaria: the hydra, anemones, & jellyfish – Radial symmetryjellyfish – Radial symmetry• Cells organized into distinct tissuesCells organized into distinct tissues• Rudimentary nerve network and contractile Rudimentary nerve network and contractile

tissuetissue• No true organsNo true organs• Two distinct body plans:Two distinct body plans:

– Polyp, attachedPolyp, attached– Medusa, free swimmingMedusa, free swimming• One digestive openingOne digestive opening• Reproduce sexually and asexuallyReproduce sexually and asexually

Chapter 22 18

Cnidarian Body:Cnidarian Body:The PolypThe Polyp

MouthMouth TentacleTentacle

BodyBodyWallWallMesogleaMesoglea

GastrovascularGastrovascularLiningLining GastrovascularGastrovascular

CavityCavityFootFoot

ColumnColumn

Chapter 22 19

Cnidarian Body:Cnidarian Body:The MedusaThe Medusa

MouthMouth

TentacleTentacle

BodyBodyWallWall

MesogleaMesoglea

GastrovascularGastrovascularLiningLining

GastrovascularGastrovascularCavityCavity

Chapter 22 20

Cnidarian Weaponry:Cnidarian Weaponry:The CnidocyteThe Cnidocyte

ArmedArmedCnidocyteCnidocyte BodyBody

WallWall

WaterWater

FilamentFilament

TriggerTrigger

NucleiNuclei

SpentSpentCnidocytCnidocytee

Chapter 22 21

The Invertebrate Phyla:The Invertebrate Phyla:PlatyhelminthesPlatyhelminthes

The flatwormsThe flatworms• Development of bilateral symmetryDevelopment of bilateral symmetry

• Ability to move forward using aggregations Ability to move forward using aggregations of nerve cells, gangliaof nerve cells, ganglia

• True organs begin to evolveTrue organs begin to evolve

•Most are hermaphroditic (can self-fertilize)Most are hermaphroditic (can self-fertilize)

•Many are free living—planariansMany are free living—planarians

• Some are parasitic—tapeworm and flukeSome are parasitic—tapeworm and fluke

Chapter 22 22

Flatworm Organ SystemsFlatworm Organ Systems(a) Digestive System(a) Digestive System

GastrovascularGastrovascularCavityCavity

PharynxPharynxPharynxPharynx

(b1) Excretory System(b1) Excretory System

Excretory CanalExcretory CanalExcretory CanalExcretory Canal

Excretory PoreExcretory PoreExcretory PoreExcretory Pore

(b2) Nervous System(b2) Nervous System Nerve CordNerve CordNerve CordNerve CordBrainBrainBrainBrain

Chapter 22 23

Measly pork marketed for Measly pork marketed for human consumption.human consumption.

Measly pork marketed for Measly pork marketed for human consumption.human consumption.

Larvae migrate through Larvae migrate through vessels to pig muscles & vessels to pig muscles & encyst there. encyst there.

Larvae migrate through Larvae migrate through vessels to pig muscles & vessels to pig muscles & encyst there. encyst there.

Larvae hatch Larvae hatch in pig intestinein pig intestine

Larvae hatch Larvae hatch in pig intestinein pig intestine

Pig eats food Pig eats food contaminated by contaminated by infected fecesinfected feces

Pig eats food Pig eats food contaminated by contaminated by infected fecesinfected feces

Adult tapewormAdult tapewormAdult tapewormAdult tapeworm

Life Cycle Life Cycle ofofHuman Human Pork Pork TapewormTapeworm

Human eats poorly Human eats poorly cooked pork with cooked pork with live cysts. live cysts.

Human eats poorly Human eats poorly cooked pork with cooked pork with live cysts. live cysts.

Larval tapeworm Larval tapeworm liberated by digestion liberated by digestion & attaches to human & attaches to human intestine.intestine.

Larval tapeworm Larval tapeworm liberated by digestion liberated by digestion & attaches to human & attaches to human intestine.intestine.

Head with hooks Head with hooks & suckers& suckers

Head with hooks Head with hooks & suckers& suckers

Tapeworm matures in Tapeworm matures in human intestine, human intestine, producing a series of producing a series of reproductive segments.reproductive segments.

Tapeworm matures in Tapeworm matures in human intestine, human intestine, producing a series of producing a series of reproductive segments.reproductive segments.

Egg-filled Egg-filled segments are segments are shed from worm shed from worm & passed in & passed in human feces.human feces.

Egg-filled Egg-filled segments are segments are shed from worm shed from worm & passed in & passed in human feces.human feces.

Chapter 22 24

The Invertebrate Phyla:The Invertebrate Phyla:Nematoda (Round Worms)Nematoda (Round Worms)

Advanced gastrovascular cavity (are Advanced gastrovascular cavity (are bilateral)bilateral)• TubularTubular• Two openingsTwo openings

Advanced sensory "ganglionic brain"Advanced sensory "ganglionic brain"Lack circulatory and respiratory systemsLack circulatory and respiratory systemsDepend on diffusion for gas exchangeDepend on diffusion for gas exchangeSexual reprouctionSexual reprouctionMost are harmless - Some parasiticMost are harmless - Some parasitic

Chapter 22 25

Heartworms in theHeartworms in theHeart of a DogHeart of a Dog

Open heartOpen heartof dogof dog

Female Female heartwormsheartworms

Chapter 22 26

The Invertebrate Phyla:The Invertebrate Phyla:Annelida (Segmented Worms)Annelida (Segmented Worms)

Bilateral symm. Bilateral symm. Repeating rings identical nerve gangliaRepeating rings identical nerve gangliaExcretory structuresExcretory structuresAdvanced locomotion abilityAdvanced locomotion abilityFluid-filled body cavity—coelom; involved in Fluid-filled body cavity—coelom; involved in

locomotion (hydrostatic skeleton)locomotion (hydrostatic skeleton)Sexual Repro. Some hermaphroditesSexual Repro. Some hermaphroditesClosed circulatory systemClosed circulatory systemEvolved many rudimentary organ systemsEvolved many rudimentary organ systems• Nervous, excretory, circulatory, muscularNervous, excretory, circulatory, muscular• Compartmentalized digestive tractCompartmentalized digestive tract

Chapter 22 27

An Annelid:An Annelid:the Earthwormthe Earthworm

MouthMouthMouthMouth

BrainBrainBrainBrain

PharynxPharynxPharynxPharynx VentralVentralVesselVessel

VentralVentralVesselVessel

VentralVentralNerve CordNerve Cord


HeartsHeartsHeartsHearts EsophagusEsophagusEsophagusEsophagus CropCropCropCrop

GizzardGizzardGizzardGizzard

IntestineIntestineIntestineIntestine



AnusAnus

CoelomCoelomCoelomCoelomIntestineIntestineIntestineIntestine

ExcretoryExcretoryPorePore

ExcretoryExcretoryPorePore

NephridiaNephridiaNephridiaNephridia

CoeloCoelomm

CoeloCoelomm

Chapter 22 28

The Invertebrate Phyla:The Invertebrate Phyla:ArthropodaArthropoda

The most numerous in numbers & speciesThe most numerous in numbers & speciesEvolutionary adaptations allow them to reside in Evolutionary adaptations allow them to reside in

diverse environmentsdiverse environments• Paired, Jointed legsPaired, Jointed legs• Exoskeleton for water conservation and supportExoskeleton for water conservation and support• SegmentationSegmentation• Well-developed sensory and nervous systemsWell-developed sensory and nervous systems• Efficient gas-exchange (gills, trachea, book lungs)Efficient gas-exchange (gills, trachea, book lungs)• Well-developed (open) circulatory systemsWell-developed (open) circulatory systems• Sense organs – compound eyesSense organs – compound eyes

Reside in both aquatic and terrestrial habitatsReside in both aquatic and terrestrial habitats

Chapter 22 29

Major Arthropod Classes:Major Arthropod Classes:InsectaInsecta

800,000 species800,000 species

Have three pairs of legsHave three pairs of legs

• Usually two pairs of wingsUsually two pairs of wings

•Make escape from predators easierMake escape from predators easier

Metamorphosis eliminates competition for Metamorphosis eliminates competition for food between generationsfood between generations

The importance of insectsThe importance of insects

Chapter 22 30

Major Arthropod Classes:Major Arthropod Classes:ArachnidaArachnida

50,000 species50,000 species• SpidersSpiders•MitesMites• TicksTicks• ScorpionsScorpions

Eight walking legsEight walking legs

CarnivorousCarnivorous

Simple eyes with a single lensSimple eyes with a single lens

Chapter 22 31

Major Arthropod Classes:Major Arthropod Classes:CrustaceaCrustacea

30,000 aquatic species30,000 aquatic species• CrabsCrabs• CrayfishCrayfish• LobsterLobster• ShrimpShrimp• BarnaclesBarnacles

Size varies from microscopic to 12 feet (3.7 m)Size varies from microscopic to 12 feet (3.7 m)Vary in number of appendages Vary in number of appendages Have two pairs of antennaeHave two pairs of antennaeGenerally with compound eyesGenerally with compound eyesExchange gases using gillsExchange gases using gills

Chapter 22 32

Insect Body PlanInsect Body Plan

WingWingWingWing

AbdomenAbdomenAbdomenAbdomen ThoraxThoraxThoraxThorax HeadHeadHeadHead AntennaeAntennaeAntennaeAntennae

CompoundCompoundEyesEyes

CompoundCompoundEyesEyes

MouthMouthPartsParts

MouthMouthPartsParts

Chapter 22 33

The Invertebrate Phyla:The Invertebrate Phyla:Mollusca (Snails & Clams)Mollusca (Snails & Clams)

Bilateral Symmetry CoelomateBilateral Symmetry CoelomateMoist muscular body without a skeletonMoist muscular body without a skeletonFound in aquatic or moist terrestrial habitatsFound in aquatic or moist terrestrial habitatsBody protected by limy shell or obnoxious tasteBody protected by limy shell or obnoxious tasteComplex, concentrated, ganglionic brainComplex, concentrated, ganglionic brainOpen circulatory systemOpen circulatory systemClassesClasses• Gastropoda—snails and sea slugsGastropoda—snails and sea slugs• Pelecypoda— scallops, oysters, mussels, & clamsPelecypoda— scallops, oysters, mussels, & clams• Cephalopoda—octopuses, squid, nautilusesCephalopoda—octopuses, squid, nautiluses

Chapter 22 34

A Generalized MolluskA Generalized MolluskTentacleTentacle

EyeEye

MouthMouthRadulaRadula

FootFoot

GangliaGanglia(brain)(brain)

GangliaGanglia(brain)(brain)

Digestive TractDigestive TractDigestive TractDigestive Tract GonadGonadGonadGonad

Nerve CordsNerve CordsNerve CordsNerve Cords

HeartHeartHeartHeart CoelomCoelomCoelomCoelom

ShellShellShellShell

MantleMantleMantleMantle

AnusAnusAnusAnus

GillGillGillGill

Chapter 22 35

The Invertebrate Phyla:The Invertebrate Phyla:Echinodermata (Sea Stars, Urchins)Echinodermata (Sea Stars, Urchins)

Bilateral as larvae – Radial as adultBilateral as larvae – Radial as adultDeuterostome developmentDeuterostome developmentCoelomateCoelomate

Possesses an endoskeleton of CaCOPossesses an endoskeleton of CaCO33

Lack a head and circulatory systemLack a head and circulatory system

Simple nervous system; no distinct brainSimple nervous system; no distinct brain

Water-vascular system for slow movementWater-vascular system for slow movement

Can regenerate lost partsCan regenerate lost parts

Chapter 22 36

Water-VascularWater-VascularSystem of EchinodermsSystem of Echinoderms

AmpullaAmpulla

CanalsCanalsPlates ofPlates of

EndoskeletonEndoskeleton

Tube FeetTube Feet

Sieve PlateSieve Plate

A MusselA Mussel(clam)(clam)

Photo (ventral)Photo (ventral)

Chapter 22 37 Key Features of ChordatesKey Features of Chordates

NotochordNotochord• Stiff flexible rod extending the length of the Stiff flexible rod extending the length of the

bodybody

Dorsal, hollow Dorsal, hollow nerve cordnerve cord• Expands anteriorly to form brainExpands anteriorly to form brain

Pharyngeal gill slitsPharyngeal gill slits• May form respiratory organs or may appear May form respiratory organs or may appear

as groovesas grooves

Post-anal tailPost-anal tail• Extends past the anusExtends past the anus

Chapter 22 38 Are Humans Chordates?Are Humans Chordates?

Only one chordate characteristic, the Only one chordate characteristic, the nerve cord, is present in adult humans; nerve cord, is present in adult humans; however, human however, human embryosembryos exhibit all exhibit all four…four…• Tail will disappear completelyTail will disappear completely• Notochord is replaced by the backboneNotochord is replaced by the backbone• Gill slits (grooves) contribute to the Gill slits (grooves) contribute to the

formation of the lower jawformation of the lower jaw

Chapter 22 39

Chapter 22 40

The Vertebrates:The Vertebrates:Chordata, VertebrataChordata, Vertebrata

SubphylaSubphyla• Invertebrates—lancelets and tunicatesInvertebrates—lancelets and tunicates

– Lack a head and backboneLack a head and backbone– marine habitatmarine habitat• VertebratesVertebrates

– Only 2.5% of extant animalsOnly 2.5% of extant animals– BackboneBackbone– Seven Major ClassesSeven Major Classes

Chapter 22 41

The Lancelet:The Lancelet:An Invertebrate ChordateAn Invertebrate Chordate

NotochordNotochordNerve CordNerve Cord

Gill SlitsGill Slits

MouthMouth

GutGut

MuscleMuscleSegmentsSegments TailTail

AnusAnus

Chapter 22 42

The Tunicate:The Tunicate:An Invertebrate ChordateAn Invertebrate Chordate

Gill SlitsGill Slits

BrainBrain MouthMouth

GutGutHeartHeart NotochordNotochordNerve CordNerve Cord

WaterWaterExitExit

ADULTADULT

LARVALARVA

Chapter 22 43

The Vertebrate Classes:The Vertebrate Classes:Agnatha & ChondrichthyesAgnatha & Chondrichthyes

Agnatha—jawless fishAgnatha—jawless fish• Skeleton of cartilage and eellike shapeSkeleton of cartilage and eellike shape• Unpaired fins, lack scalesUnpaired fins, lack scales• Slimy skin perforated by circular gill openingsSlimy skin perforated by circular gill openings

ChondrichthyesChondrichthyes• ““Cartilaginous fishes”—sharks, skates, & raysCartilaginous fishes”—sharks, skates, & rays• Leathery skinLeathery skin• Respire by gillsRespire by gills• Two-chamber heartTwo-chamber heart

Chapter 22 44 A HagfishA HagfishA HagfishA Hagfish

Chapter 22 45 Lobe-Finned FishesLobe-Finned Fishes

Lungfish are found in freshwater Lungfish are found in freshwater habitats habitats

Have both gills and lungsHave both gills and lungsTend to live in stagnant waters low in Tend to live in stagnant waters low in oxygenoxygen

Lungs allow them to supplement their Lungs allow them to supplement their supply of oxygen by breathing air supply of oxygen by breathing air directlydirectly

Chapter 22 46 Lobe-Finned FishesLobe-Finned Fishes

Some species can survive even if the Some species can survive even if the water dries up water dries up • Burrow into mud, Seal themselves in a Burrow into mud, Seal themselves in a

mucous-lined chamber and breathe mucous-lined chamber and breathe through lungs as metabolic rate slows, through lungs as metabolic rate slows, Resume underwater life when rains Resume underwater life when rains return and pool refillsreturn and pool refills

Chapter 22 47

Chapter 22 48

The Vertebrate Classes:The Vertebrate Classes:OsteichthyesOsteichthyes

““Bony fishes”Bony fishes”

Varied formsVaried forms

Supplemental lungs for freshwater livingSupplemental lungs for freshwater living

Fleshy fins Fleshy fins

Chapter 22 49

The Vertebrate Classes:The Vertebrate Classes:AmphibiaAmphibia

Bony support for the bodyBony support for the body

Waterproofing for the skin and eggsWaterproofing for the skin and eggs

Moist protection of respiratory membranesMoist protection of respiratory membranes

Development of adult lungsDevelopment of adult lungs

Cold Blooded --- External FertilizationCold Blooded --- External Fertilization

Still need aquatic habitat for reproductionStill need aquatic habitat for reproduction

3 chambered heart3 chambered heart

Chapter 22 50 Amphibians Live a Double LifeAmphibians Live a Double Life

Include frogs, toads, and salamandersInclude frogs, toads, and salamanders““Double life” of amphibiansDouble life” of amphibians• Begin life adapted to aquatic Begin life adapted to aquatic

environment (eg tadpoles have gills)environment (eg tadpoles have gills)•Mature into semiterrestrial adult with Mature into semiterrestrial adult with

lungslungs

Chapter 22 51

Chapter 22 52

The Vertebrate Classes:The Vertebrate Classes:ReptiliaReptilia

Turtles, alligators, crocodiles, dinosaurs, birdsTurtles, alligators, crocodiles, dinosaurs, birds

Respire through LungsRespire through Lungs

Internal fertilizationInternal fertilization

Shelled amniotic egg (encapsulates embryo in a Shelled amniotic egg (encapsulates embryo in a liquid filled membrane, the liquid filled membrane, the amnionamnion))

Skeleton modified for better support and Skeleton modified for better support and locomotionlocomotion

Chapter 22 53 BirdsBirds

Appeared in the fossil record about 150 Appeared in the fossil record about 150 million years agomillion years ago

Considered by modern systematists to Considered by modern systematists to be feathered reptilesbe feathered reptiles• The earliest known bird, The earliest known bird, ArchaeopteryxArchaeopteryx

Chapter 22 54

Chapter 22 55 BirdsBirds

Distinctive group of “reptiles” adapted for Distinctive group of “reptiles” adapted for flightflight• Feathers (provide lift and control as well as Feathers (provide lift and control as well as

insulation)insulation)• Hollow bones (reduce weight of skeleton)Hollow bones (reduce weight of skeleton)• Females have a single ovaryFemales have a single ovary• Shelled egg (frees female from carrying Shelled egg (frees female from carrying

developing offspring)developing offspring)

Maintain a constant body temperature Maintain a constant body temperature (warm-blooded) (warm-blooded)

Chapter 22 56

The Vertebrate Classes:The Vertebrate Classes:MammaliaMammalia

Warm-bloodedWarm-bloodedFour-chambered heartFour-chambered heartFur for insulation and protectionFur for insulation and protectionLegs for running fast to avoid predatorsLegs for running fast to avoid predatorsMammary glands to nurse live-born youngMammary glands to nurse live-born youngComplex cerebral cortex—increased learning Complex cerebral cortex—increased learning

abilityabilityIncludesIncludes• Egg-laying monotremes (platypus)Egg-laying monotremes (platypus)• Marsupials (opossums, koalas, kangaroos) Marsupials (opossums, koalas, kangaroos) • Placental mammals (most other mammals)Placental mammals (most other mammals)

Chapter 22 57 MammalsMammals

Appeared in the fossil record about 250 Appeared in the fossil record about 250 million years agomillion years ago

Did not diversify and dominate Did not diversify and dominate terrestrial habitats until the dinosaurs terrestrial habitats until the dinosaurs became extinct (65 million years ago)became extinct (65 million years ago)

Chapter 22 58

Bats,Bats,the Only Flying Mammalsthe Only Flying Mammals

Chapter 22Chapter 22

The EndThe End

animal apbio

Business