Ch. 32 Animal Diversity - philipdarrenjones.com
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AnimalDiversityAnimalDiversityBIOL221
Ch.32
• 1.3millionlivingspeciesofanimals
• havebeeniden;fied
• Thereareexcep;onstonearlyeverycriterionfor
dis;nguishinganimalsfromotherlife‐forms
• Severalcharacteris;cs,takentogether
• sufficientlydefinethegroup
Characteris2csofAnimalsCharacteris2csofAnimals
Nutri2on,CellStructureandSpecializa2onNutri2on,CellStructureandSpecializa2on
• Animals
• heterotrophsthatingesttheirfood
• mul;cellulareukaryotes
• lackcellwalls
• bodiesareheldtogetherbystructural
proteins
• suchascollagen
• Nervous;ssueandmuscle;ssue
• uniquetoanimals
Reproduc2onandDevelopmentReproduc2onandDevelopment
• Mostanimalsreproducesexually
• diploidstagedominateslifecycle
• AMeraspermfer;lizesanegg
• zygoteundergoesrapidcelldivision
• calledcleavage
• subdivision
• leadstoblastula
• undergoesgastrula2on
• formingagastrula
• withdifferentlayersofembryonic;ssues
Fig.Fig. 32‐2‐132‐2‐1
Zygote
Cleavage
Eight-cell stage
Fig.Fig. 32‐2‐232‐2‐2
Zygote
Cleavage
Eight-cell stage
Cleavage Blastula
Cross sectionof blastula
Blastocoel
Fig.Fig. 32‐2‐332‐2‐3
Zygote
Cleavage
Eight-cell stage
Cleavage Blastula
Cross sectionof blastula
BlastocoelGastrulation
BlastoporeGastrula
Archenteron
Ectoderm
Endoderm
Blastocoel
Video
• Manyanimals
• haveatleastonelarvalstage
• larva
• sexuallyimmatureand
morphologicallydis;nctfromtheadult
• eventuallyundergoes
metamorphosis
Reproduc2onandDevelopmentReproduc2onandDevelopment
• Allanimals,andonlyanimals
• haveHoxgenes
• regulatethedevelopmentofbodyform
• Hoxfamilyofgeneshasbeenhighlyconserved
• butcanproduceawidediversityofanimalmorphology
Reproduc2onandDevelopmentReproduc2onandDevelopment
HalfabillionyearsofAnimalsHalfabillionyearsofAnimals
• Theanimalkingdomincludesgreatdiversityoflivingspecies
• evengreaterdiversityofex;nctones
• Commonancestoroflivinganimals
• mayhavelivedbetween675and875millionyearsago
• mayhaveresembledmodernchoanoflagellates
• pro;ststhataretheclosestlivingrela;vesof
animals
Fig.Fig. 32‐332‐3
OTHEREUKARYOTES
Choanoflagellates
Sponges
Other animals
Anim
als
Individualchoanoflagellate
Collar cell(choanocyte)
NeoproterozoicEra(1BillionNeoproterozoicEra(1Billion––524MillionYearsAgo)524MillionYearsAgo)
• Earlymembersoftheanimal
fossilrecord
• Ediacaranbiota
• 565to550million
yearsago
Fig.Fig. 32‐432‐4
(a) Mawsonites spriggi (b) Spriggina floundersi
1.5 cm 0.4 cm
PaleozoicEra(542PaleozoicEra(542––251MillionYearsAgo)251MillionYearsAgo)
• Cambrianexplosion(535to525
millionyearsago)
• earliestfossilappearanceof
manymajorgroupsofliving
animals
• Severalhypothesesregardingthe
causeoftheCambrianexplosion
• Newpredator‐preyrela;onships
• Ariseinatmosphericoxygen
• Theevolu;onoftheHoxgene
complex
Fig.Fig. 32‐532‐5
AnimalDiversityAnimalDiversity• Animaldiversity
• con;nuedtoincreasethroughthePaleozoic
• butpunctuatedbymassex;nc;ons
• begantomakeanimpactonland
• by460millionyearsago
• Vertebratesmadethetransi;ontoland
• around360millionyearsago
MesozoicEra(251MesozoicEra(251––65.5MillionYearsAgo)65.5MillionYearsAgo)
• Coralreefsemerged
• becomingimportantmarineecologicalnichesforotherorganisms
• Dinosaurswerethedominantterrestrialvertebrates
• Firstmammalsemerged
CenozoicEra(65.5MillionYearsAgotothePresent)CenozoicEra(65.5MillionYearsAgotothePresent)• ThebeginningoftheCenozoicera
• followedmassex;nc;onsofbothterrestrialandmarineanimals
• Theseex;nc;onsincludedthelarge
• nonflyingdinosaursandthemarinerep;les
• Modernmammalordersandinsects
• diversifiedduringtheCenozoic
AnimalscanbecharacterizedbyAnimalscanbecharacterizedby““bodyplansbodyplans””
• Zoologists
• some;mescategorizeanimalsaccordingtoabody
plan
• asetofmorphologicalanddevelopmentaltraits
• Agrade
• agroupwhosememberssharekeybiologicalfeatures
• notnecessarilyaclade,ormonophyle;cgroup
SymmetrySymmetry
• Animalscanbecategorized
• accordingtothesymmetryoftheirbodies
• orlackofit
• Someanimalshave
• radialsymmetry
• Pieslicesarethesame
• bilateralsymmetry
• Two‐sidedsymmetry
• Adorsal(top)sideandaventral(bo`om)side
• ArightandleMside
• Anterior(head)andposterior(tail)ends
• Cephaliza2on,thedevelopmentofahead
Fig.Fig. 32‐732‐7
(a) Radial symmetry
(b) Bilateral symmetry
TissuesTissues
• Animalbodyplans
• alsovaryaccordingtotheorganiza;onoftheanimal’s;ssues
• Tissues
• collec;onsofspecializedcells
• isolatedfromother;ssuesbymembranouslayers
• Duringdevelopment
• threegermlayersgiverisetothe;ssuesandorgansoftheanimalembryo
• Ectoderm,mesoderm,endoderm
• Ectoderm
• thegermlayercoveringtheembryo’ssurface
• Endoderm
• innermostgermlayer
• linesthedevelopingdiges;vetube
• calledthearchenteron
• Diploblas2c
• animalshaveectodermandendoderm
• Triploblas2c
• animalsalsohaveaninterveningmesodermlayer
• theseincludeallbilaterians
GermLayersGermLayers
BodyCavi2esBodyCavi2es
• Mosttriploblas;canimals
• possessabodycavity
• Atruebodycavity
• calledacoelom
• derivedfrom
mesoderm
• Coelomates
• animalsthatpossessa
truecoelom
Fig.Fig. 32‐8a32‐8a
CoelomBody covering(from ectoderm)
Digestive tract(from endoderm)
Tissue layerlining coelomand suspendinginternal organs (from mesoderm)
(a) Coelomate
• pseudocoelom
• bodycavityderived
fromthemesodermand
endoderm
• Notlinedby
mesodermonall
sides
• pseudocoelomates
• Triploblas;canimals
thatpossessa
pseudocoelom
BodyCavi2esBodyCavi2es
Fig.Fig. 32‐8b32‐8b
Pseudocoelom
Body covering(from ectoderm)
Muscle layer(frommesoderm)
Digestive tract(from endoderm)
(b) Pseudocoelomate
• acoelomates
• Triploblas;canimalsthatlackabodycavityarecalled
BodyCavi2esBodyCavi2es
(c) Acoelomate
Body covering(from ectoderm)
Wall of digestive cavity(from endoderm)
Tissue-filled region(from mesoderm)
ProtostomeandDeuterostomeDevelopmentProtostomeandDeuterostomeDevelopment
• Basedonearlydevelopment
• manyanimalscanbecategorized
• ashavingprotostomedevelopment
• ordeuterostomedevelopment
CleavageCleavage
• protostomedevelopment
• cleavageisspiralanddeterminate
• deuterostomedevelopment
• cleavageisradialandindeterminate
• indeterminatecleavage
• eachcellintheearlystagesofcleavage
• retainsthecapacitytodevelopintoacompleteembryo
• makespossibleiden;caltwins,andembryonicstemcells
Fig.Fig. 32‐932‐9
Protostome development(examples: molluscs,
annelids)
Deuterostome development(examples: echinoderm,
chordates)
Eight-cell stage Eight-cell stage
Spiral and determinate Radial and indeterminate
Coelom
Archenteron
(a) Cleavage
(b) Coelom formation
Coelom
KeyEctodermMesodermEndoderm
Mesoderm MesodermBlastopore BlastoporeSolid masses of mesodermsplit and form coelom.
Folds of archenteronform coelom.
Anus Mouth
Digestive tube
Mouth AnusMouth develops from blastopore. Anus develops from blastopore.
(c) Fate of the blastopore
CoelomForma2onCoelomForma2on
• Inprotostomedevelopment
• splibngofsolidmassesofmesodermformsthe
coelom
• Indeuterostomedevelopment
• mesodermbudsfromthewallofthearchenteronto
formthecoelom
Fig.Fig. 32‐9b32‐9b
Coelom
Protostome development(examples: molluscs,
annelids)
Deuterostome development(examples: echinoderms,
chordates)
(b) Coelom formation
KeyEctodermMesodermEndoderm
MesodermMesodermCoelom
Archenteron
Blastopore BlastoporeSolid masses of mesodermsplit and form coelom.
Folds of archenteronform coelom.
FateoftheBlastoporeFateoftheBlastopore
• Theblastopore
• formsduringgastrula;on
• connectsthearchenterontotheexteriorofthegastrula
• Inprotostomedevelopment
• blastoporebecomesthemouth
• Indeuterostomedevelopment
• blastoporebecomestheanus
Fig.Fig. 32‐9c32‐9c
Anus
Protostome development(examples: molluscs,
annelids)
Deuterostome development(examples: echinoderms,
chordates)
Anus
Mouth
Mouth
Digestive tube
(c) Fate of the blastopore
KeyEctodermMesodermEndoderm
Mouth develops from blastopore. Anus develops from blastopore.
AnimalphylogenyfrommoleculardataAnimalphylogenyfrommoleculardata
• Zoologists
• recognizeaboutthreedozenanimalphyla
• Currentdebateinanimalsystema;cs
• hasledtothedevelopmentoftwophylogene;chypotheses
• butothersexistaswell
• Onehypothesisofanimalphylogeny
• isbasedmainlyonmorphologicalanddevelopmental
comparisons
• Anotherhypothesisofanimalphylogeny
• isbasedmainlyonmoleculardata
Fig.Fig. 32‐1032‐10
ANCESTRALCOLONIALFLAGELLATE
Metazoa Eum
etazoa
“Porifera”
Bilateria
Deuterostom
iaProtostom
ia
Cnidaria
Ctenophora
Ectoprocta
Brachiopoda
Echinodermata
Chordata
Platyhelminthes
Rotifera
Mollusca
Annelida
Arthropoda
Nematoda
Fig.Fig. 32‐1132‐11
Silicea
ANCESTRALCOLONIALFLAGELLATE
Metazoa
Eumetazoa
“Porifera”B
ilateria
Deuterostom
iaLophotrochozoa
Ecdysozoa
Calcarea
Ctenophora
Cnidaria
Acoela
Echinodermata
Chordata
Platyhelminthes
Rotifera
Ectoprocta
Brachiopoda
Mollusca
Annelida
Nematoda
Arthropoda
PointsofAgreementPointsofAgreement
• Allanimalsshareacommonancestor
• Spongesarebasalanimals
• Eumetazoaisacladeofanimals(eumetazoans)
• withtrue;ssues
• MostanimalphylabelongtothecladeBilateria
• calledbilaterians
• Chordatesandsomeotherphyla
• belongtothecladeDeuterostomia
ProgressinResolvingBilaterianRela2onshipsProgressinResolvingBilaterianRela2onships
• Themorphology‐basedtree
• dividesbilateriansintotwoclades
• deuterostomesandprotostomes
• Incontrast,recentmolecularstudies
• indicatethreebilaterianclades
• Deuterostomia,Ecdysozoa,andLophotrochozoa
• Ecdysozoans
• shedtheirexoskeletonsthroughaprocesscalledecdysis
Fig.Fig. 32‐1232‐12
• Somelophotrochozoans
• haveafeedingstructurecalledalophophore
• Otherphylagothroughadis;nctdevelopmentalstage
• calledthetrochophorelarva
ProgressinResolvingBilaterianRela2onshipsProgressinResolvingBilaterianRela2onships
Fig.Fig. 32‐1332‐13
LophophoreApical tuftof cilia
Mouth
(a) An ectoproct (b) Structure of a trochophore larva
100 µm
Anus
FutureDirec2onsinAnimalSystema2csFutureDirec2onsinAnimalSystema2cs
• Phylogene;cstudies
• basedonlargerdatabases
• willlikelyprovidefurtherinsightsintoanimal
evolu;onaryhistory
Youshouldnowbeableto:Youshouldnowbeableto:
1. Listthecharacteris;csthatcombinetodefineanimals
2. SummarizekeyeventsofthePaleozoic,Mesozoic,andCenozoiceras
3. Dis;nguishbetweenthefollowingpairsorsetsofterms:radialandbilateralsymmetry;gradeandcladeofanimaltaxa;diploblas;candtriploblas;c;spiralandradialcleavage;determinateandindeterminatecleavage;acoelomate,pseudocoelomate,andcoelomategrades
4. Comparethedevelopmentaldifferencesbetweenprotostomesanddeuterostomes
5. Comparethealternaterela;onshipsofannelidsandarthropodspresentedbytwodifferentproposedphylogene;ctrees
6. Dis;nguishbetweenecdysozoansandlophotrochozoans
Youshouldnowbeableto:Youshouldnowbeableto:
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