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Chapter 19Chapter 19
The Animal The Animal KingdomKingdom
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
3
Animal EvolutionAnimal EvolutionMost 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
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
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
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
7Body CavitiesBody Cavities
AcoelomateAcoelomate animals lack a body cavity animals lack a body cavity• e.g. flatwormse.g. flatworms
8Body 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
9Body CavitiesBody Cavities
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)
10Body 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
11
Body CavitiesBody Cavities
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
12Body 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
13Embryological 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
15The 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))
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
18Cnidarian Body:Cnidarian Body:The PolypThe Polyp
MouthMouth TentacleTentacle
BodyBodyWallWallMesogleaMesoglea
GastrovascularGastrovascularLiningLining GastrovascularGastrovascular
CavityCavityFootFoot
ColumnColumn
19Cnidarian Body:Cnidarian Body:The MedusaThe Medusa
MouthMouth
TentacleTentacle
BodyBodyWallWall
MesogleaMesoglea
GastrovascularGastrovascularLiningLining
GastrovascularGastrovascularCavityCavity
20Cnidarian Weaponry:Cnidarian Weaponry:The CnidocyteThe Cnidocyte
ArmedArmedCnidocyteCnidocyte BodyBody
WallWall
WaterWater
FilamentFilament
TriggerTrigger
NucleiNuclei
SpentSpentCnidocytCnidocytee
21The 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
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.
24The 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
25Heartworms in theHeartworms in theHeart of a DogHeart of a Dog
Open heartOpen heartof dogof dog
Female Female heartwormsheartworms
26The 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
VentralVentralNerve CordNerve Cord
HeartsHeartsHeartsHearts EsophagusEsophagusEsophagusEsophagus CropCropCropCrop
GizzardGizzardGizzardGizzard
IntestineIntestineIntestineIntestine
VentralVentralNerve CordNerve Cord
VentralVentralNerve CordNerve Cord
AnusAnus
CoelomCoelomCoelomCoelomIntestineIntestineIntestineIntestine
ExcretoryExcretoryPorePore
ExcretoryExcretoryPorePore
NephridiaNephridiaNephridiaNephridia
CoeloCoelomm
CoeloCoelomm
28The 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
29Major 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
30Major 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
31Major 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
32
Insect Body PlanInsect Body Plan
WingWingWingWing
AbdomenAbdomenAbdomenAbdomen ThoraxThoraxThoraxThorax HeadHeadHeadHead AntennaeAntennaeAntennaeAntennae
CompoundCompoundEyesEyes
CompoundCompoundEyesEyes
MouthMouthPartsParts
MouthMouthPartsParts
33The 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
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
35The 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
36Water-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)
37
Key Features of ChordatesKey Features of ChordatesNotochordNotochord• 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
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
40The 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
41The Lancelet:The Lancelet:An Invertebrate ChordateAn Invertebrate Chordate
NotochordNotochordNerve CordNerve Cord
Gill SlitsGill Slits
MouthMouth
GutGut
MuscleMuscleSegmentsSegments TailTail
AnusAnus
42The Tunicate:The Tunicate:An Invertebrate ChordateAn Invertebrate Chordate
Gill SlitsGill Slits
BrainBrain MouthMouth
GutGutHeartHeart NotochordNotochordNerve CordNerve Cord
WaterWaterExitExit
ADULTADULT
LARVALARVA
43The 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
44A HagfishA HagfishA HagfishA Hagfish
45Lobe-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
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
47
48The 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
49The 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
50Amphibians Live a Amphibians Live a Double LifeDouble 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
51
52The 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
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
54
55
BirdsBirdsDistinctive 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)
56The 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)
57MammalsMammals
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)
58Bats,Bats,the Only Flying Mammalsthe Only Flying Mammals
Chapter 22Chapter 22
The EndThe End