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n ma
vers ca on
o ay sques ons:
I. W atarean ma s
II. Howdid
body
plans
change
as
animals
vers e
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I. Whatareanimals?
Feedingandmoving
mac ines
phylogeny
Epithelium
Ecto/endoderm
Mesoderm
Diploblast
Triploblast
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II.Howdidbodyplanschangeasanimalsdiversified?
A.
Multicellularity and
tissuesAllanimalsaremulticellular
Cellsbindtoeachother
Cellscommunicate
Divisionoflabor(somecellsfunctioninfeeding
vs.structurevs.reproduction)
Multicellularity evolvedindependently
in
fungi,
plants,andseverallineagesofalgae.Aretheprocesses
abovesameordifferent?- Homoplasy due to independent evolution.- As such, there is likely to be variation between the traits.
- Different traits to serve same function.
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Originoftissues
(integratedgroupsof
cellsthatperformaparticularfunction)
Whereto
map
origin?
Tissues
c o erm
Endoderm
Mesoderm
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B.Bodysymmetryandcephalization
Classically:
Radialsymmetryindiploblasts
Bilateralsymmetryintriploblasts
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y y
w
z :
1)centralizedneurons;2)ganglia(brain)+sensoryorgans
Posteriorregionspecializedfordigestion,reproduction,
locomotion adaptivesignificance?
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Reversiontoradialsymmetryinechinoderms
en ara a symme ry na u s ; arvaeare a era y
symmetric
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C.Evolutionofabodycavity(coelom)
Functions:
Hydrostaticskeletonimportantinmovement
,
Tubewithin
atube
body
design
Water being squished will force it into another area, forcing movement
in that direction.
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D.Developmentalpatterns
Classicall :
1. Protostome development Spiralcleavage
Coelom frommesoderm
blocks
2.Deuterostome development
Radialcleavage
Mouthsecond
gastrulation
Coelom frompinchedoff
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E.Segmentation
Repeatedstructuralunitsinabody:annelids
(segmentedworms),arthropods,vertebrates
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F.Growthpatterns
continuousgrowth
e amorp os s
No competition between them since
they use different resources.
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Questions:
1. Areannelidsmore
derivedthansponges?
2.Whichanimalsare
basal?
3.Islossofthecoelom in
mollusks,echinoderms,
and
chordateshomologous?
No animals is really more derived than
another.
Homoplasic, ancestor of mollusk had coelom.
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