Lecture'18'Bio'200''Animal'Diversity:'• Totally'surrounded'by'animals'at'all'times'even'if'we'cant'see'them'• Diverse'in'size'• Almost'all'animals'occur'in'the'marine'environment,'few'are'in'fresh'water'and'very'few'on'land'• We'name'currently'36'different'phyla'(major'groups'of'animals)'• At'least'1.2'million'species'of'animals'and'many'more'that'we'haven’t'discovered'or'named'• Over'95%'of'the'known'animals'are'invertebrates'• Over'75%'of'invertebrates'are'insects'alone.'• Only'60,000'species'are'considered'vertebrates'(like'humans)''What'makes'an'animal?'• Even'if'there'is'a'vast'diversity'of'forms'of'animals,'there'are'some'general'traits'that'we'see'in'all'or'most'animals.''• We'see'multiScellularity,'we'also'see'this'in'the'plants'and'fungi.'• Heterotrophy'metabolism,'we'also'see'this'in'fungi.'But'the'animals'digest'the'food'differently'from'the'fungi.'Fungi'obtain'nutrients'externally.'• Animals'use'internal'processes'to'break'down'materials'from'environment,'break'them'down'into'the'molecules'they'need'• Most'animals'have'an'internal'gut'in'which'the'digestion'takes'place'• ALL'LACK'CELL'WALLS'• All'able'to'move'at'some'point'in'life'cycle'• Defined'by'their'almost'ubiquitous'sexual'reproduction'with'unique'haploid'gametes.''• Characteristic'embryonic'development'• Specialized'tissues'• All'these'common'traits'that'are'shared'by'animals'suggest'that'animals'ARE'A'MONOPHYLETIC'GROUP.'• Surprising'a'few'are'morphological'features'are'shared'across'species'of'animals.'We'do'see'some'exceptions'though.''• Unique'junctions'that'link'adjacent'animal'cells'together.''• The'animal’s'cells'have'an'extra'cellular'matrix'that'holds'the'animal’s'cells'together'and'plays'an'important'role'in'chemical'signaling'and'also'have'many'important'other'functions'''''Main'Traits:'• SymmetryS''! Symmetry'is'when'you'place'and'imaginary'axis'on'something'and'then'being'able'to'split'it'in'identical'halves.''! The'spongesS'earliest'animals.'They'lack'true'symmetry'because'they'generally'grow'in'indeterminate'masses.''! But'all'the'remaining'animals'have'some'sort'of'symmetry'that'is'either'radial'or'bilateral.''! RadialS'first'form'that'evolves.'It'leads'to'body'designs,'that'the'parts'of'the'body'are'arranged'around'a'central'point.'You'can'divide'these'organisms'in'half'and'have'any'twoSdimension'plane.'They'are'generally'circular'or'spherical.'! Radial'organisms'are'very'basal'in'the'animal'tree'with'one'notable'exception.'! They'are'organism'like'anemones'and'jellyfish.''! Bilateral'SymmetryS'evolves'after'radial'symmetry.'It'consists'of'a'body'plan'where'the'right'and'left'halves'are'mirror'images.''! There'is'a'only'a'single'plane'of'symmetry'in'the'animals'that'have'bilateral'symmetry.'These'animals'are'called'bilaterians.''! These'bilaterians'also'have'a'top'and'bottom,'the'dorsal'side'is'the'back'and'the'ventral'side'is'the'belly.''! Bilateral'Symmetry'is'a'great'advance'because'different'functions'can'now'cluster'in'different'parts'of'the'body.'! We'have'a'sensory'and'neural'organs'that'over'time'that'have'generally'been'concentrated'in'the'anterior'end'(the'head).'! This'concentration'of'the'sensory'and'neural'organs'in'the'anterior'ends'is'called'cephalization.''! This'lead'to'the'evolution'of'a'definite'brain'area'which'shows'dominance'of'these'organs'for'organism'functioning''''''''''''''Development:''Another'way'we'divide'the'animals'is'how'they'develop'as'embryos'! Different'patterns'of'embryonic'development'that'we'see'in'the'animals'indicate'an'evolutionary'trend'towards'the'formation'of'more'complex'organisms.'! Early'in'animal'development,'specific'layers'of'cells'form.'These'layers'will'eventually'form'different'tissues'and'different'organs'in'the'mature'animal.''! All'animals'other'than'the'sponges'(which'are'the'most'basal'animals,)'have'these'differentiated'layers.'! Diploblastic'Animals:'jelly'fish'&'anemones,'have'two'layers.'Have'an'outer'ectoderm,'and'an'inner'endoderm.''! Triploblastic'Animals:'have'3'embryonic'tissue'layers.'Most'of'the'animals'are'these.'In'addition'to'the'ectoderm'and'endoderm,'they'also'have'a'distinct'mesoderm'tissue,'between'ectoderm'and'endoderm.''! Ectoderm:'• Outter'body'covering'• Nervous'system'! Mesoderm:''• Skeleton'• Muscle'! Endoderm:'• Digestive'organs'• Intestines'! The'various'tissues'in'these'layers'allow'for'the'differentiation'for'cell,'differential'allows'for'more'functions'like'movement'and'thinking.''We'have'muscle'tissue'and'nervous'tissue.'This'functional'specialization'has'allowed'for'increasing'form'and'function'in'the'animals.''''''! 'Symmetry'and'tissue'layers'will'divide'animals'into'three'different'groups:'1. Sponges/Basal'animals''2. Diploblasts/radial''''3. Triploblasts/bilateriansS''! changes'in'how'these'3'layers'organized,'influences'how'these'animals'move'and'how'efficient'they'move.'This'is'determined'by'the'body'cavity'between'the'mesoderm'and'endoderm.'This'body'cavity'is'referred'to'as'the'coelom.''! The'presence'of'the'coelom'varies'between'animals.'''''''The'AcoelomatesS''' '! have'no'space'between'the'tissue'layers'so'they'no'coelom.'How'do'they'move?'Usually,'they'have'cilia'to'make'them'move.'The'PseudocoelomateS''! ex:'round'worms.'There'is'a'cavity/coelom,'but'it'fluid'filled'and'serves'the'organism'as'a'hydrostatic'skeleton,'this'means'they'will'gain'ridgity'because'they'are'filled'with'fluid.''! These'animals'are'firm''! The'muscles'work'against'the'skeleton'by'pushing'the'fluid'into'other'parts'of'the'body.''! Movement'is'more'efficient'than'in'the'Acoelomate.'! The'fluid'in'the'hydrostatic'skeleton'also'functions'as'the'circularity'system'in'the'animals.'These'animals'have'organs'within'the'cavity,'but'these'organs'are'NOT'surrounded'by'muscles'or'mesoderm.'''The'coelomateS''! ex:'earthworm.'The'coelom'forms'entirely'within'the'mesoderm.''! Have'a'body'cavity'with'muscel'lining'the'inside'and'outside'so'the'organs'are'lined'in'musciel'.This'extra'muscular'give'the'coelomates'much'more'control'of'movement'than'the'acoelomates'and'pseudocelomate.'Most'bilateral'animals,'including'vertebrates'and'humans'are'coelomates.''''''Bilaterians:''•
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