Lecture'21'Bio'200''Vertebrates2'o Lineage'is'very'small'compared'to'the'tree'of'life'o Fairly'few'species'o Most'vertebrates'are'chordates'o monophyletic''4'Traits'all'Vertebrates'have:'o Heads'• Defined'as'an'interior'skull'that'cont a ins'a'brain'• The'skull'is'the'protective'covering'is'made'of'bone'and'cartilage'• The'vertebrates'have'3'sensory'organisms:'• Eyes'• Ears'• Nose'&'mouth'combination''o Endoskeletons'supported'by'vertebrates'• The'notochord'is'replaced'by'the'vertebral'column''• This'column'is'a'made'up'of'bony'or'cartilage''vertebrae'that'protects'the'dorsal'nerve'core'• Inside'the'spine'is'the'major'nerve'core'of'the'body'• The'dorsal'nerve'cord'is'found'in'all'the'chordates,'it'allows'the'brain'to'control'movements,'why'spinal'chord'injuries'are'so'serious,'it'severs'communications'between'brain'and'body.'• The'endoskeleton'that'the'vertebral'column'supports'is'one'of'the'major'features'that'has'allowed'the'vertebrates'to'get'so'large.'• This'internal'skeleton'is'made'of'cartilage'or'bone'• These'materials'are'actually'advantageous'structural'materials'when'we'compare'them'to'something'like'chitin'(exoskeletons'of'insects),'because'these'materials'are'actually'living.'Therefore'it'is'growing.'Tissue'that'is'strong,'without'being'brittle.'''o Internal'organs'suspended'in'a'coelom'• Lungs'• Kidney'• Liver'• Stomach'• Heart'• Endocrine'glands2'secrete'hormans'that'help'regulate'the'vertebrates'bodily'functions'• All'of'these'organs'are'suspended'in'a'coelom'in'all'the'vertebrates''''o Circulatory'system'with'a'muscular'heart'• Extremely'well'developed'circularity'system'that'is'powered'by'a'ventrically'placed'heart.'• Circulation'is'important'if'you'are'going'to'be'big.'• This'is'because'you'have'to'move'nutrients'and'waste'throughout'a'much'larger'area,'similar'to'the'vascular'system'of'land'plants''Dueterostome'tree:'• The'tunicates'are'the'sister'taxa'to'the'vertebrates'• Besides'the'derived'features'of'vertebrates,'they'have'similar'features'with'non2vertebrates:'like'the'notochord,'tail,'and'nere'chord'• We'have'an'even'closer'non2vertebrate'group,'the'hagfishes'Hagfish2'• Have'a'weak'circulatory'system'• Have'three'accessory'hearts'instead'of'1'• Only'have'partial'skull'that'encases'a'brain'without'a'cerebrum'or'cerebellum'• No'jaws'• No'stomach'• Lack'separate'jointed'vertebrae'• Skeleton'composed'of'cartilage'• Not'enough'like'vertebrates'to'be'included'• They'are'just'a'sister'group'• DNA'sequence'data'places'hagfish'closer'to'the'modern'Lamprey''Lamprey:'• Very'basic'creature'• Most'are'parasites'attached'to'the'bodies'of'living'fish'using'their'large'mouths'to'suck'blood'and'flesh'• Vertebrates'• Complete'skull'• Distinct'vertebrae'• If'this'DNA'evidence'is'true'about'lamprey'and'hagfish,'we'would'consider'them'the'first'vertebrate,'we'would'call'them'Cyclostomes'or'Circle'Mouths'• We'would'have'to'change'the'tree,'they'would'be'monophyletic'and'be'sisters'to'vertebrates.''Vertebrates'are'considered'as'5'major'groups:''• The'fish,'paraphyletic'grade'of'4'lineages'• The'amphibians'• The'mamamasl'• Reptiles'• Birds''Amniotes:'• Where'the'reptiles,'including'the'birds'and'mammals.''''Fish:'• Most'diverse'of'vertebrates,'over'half'of'the'species'• Fully'aquatic'group'• Adaptations'in'the'fish'allowed'for'the'invasion'of'land'by'amphibians'• Houses'eels,'ex:'ribbon'eel'• Seahorses'ex:'sea'dragon'• Yellow'fin'tuna'• Sharks'• When'we'get'to'the'higher'fish,'not'the'lamprey’s'and'hagfish…'then'there'are'5'traits'that'unify'them:'o Jaws'and'teeth'allow'fish'to'catch'and'eat'and'chew'larger'and'active'prey.'This'increased'feeding'efficiency,'helps'to'support'larger'organisms''o Most'fish'have'two'appendages,'which'are'fins.'A'pectral'pair2'at'the'shoulder,'and'pelvic'pair'at'the'hip.'This'help s' the'fish'stabilize'the'fishes'position'in'water.'The'pair'fins'will'evolve't o' be'jointed.''o Internal'gills2'allow'aquatic'organisms'to'extract'oxygen'from'the'water'around'them''o Single'loop'blood'circulation2'blood'is'pumped'from'heart'to'the'gills.'Oxygenated'there'and'passed'to'the'rest'of'the'body'to'be'returned'to'the'heart'(humans'circulatory'system'is'doubled,'separate'system'that'flow'to'the'lungs'and'rest'of'the'system,'double'looped'system''o Fish'are'unable'to'synthesize'3'amino'acids.'Fish'must'consume'these'amino'acids'in'their'food.'''Phylogenetic'relationships'in'the'fish:'Jawed'Fishes:'o Evolved'Anterior'gill'arches'became'jaws'and'greatly'improved'feeding'efficiency'o Jaws'greatly'improved'feeding'o The'primitive'jawed'fishes,'the'Placoderms2'now'extinct…'They'actually'rapidly'diversified'the'seas'in'the'Paleozoic'area.'A'recent'study'of'placoderm'fossils'shows'another'interesting'piece'of'info…'They'appeared'the'be'the'first'backbone'fishes'that'evolved'male'genitalia'organs'called'claspers.'Supported'by'a'boney'internal'skeletal'organ.'May'have'been'the'first'vertebrate'organism'with'complex'form'of'sexual'reproduction…'male'fertilize'female'internally'rather'than'spawning'in'water.' This' suggests'that'internal'fertilization'in'vertebrates'began'in'the'seas'and'began'a'very'long'time'ago,'385'MYA.''o These'primitive'jawed'fish'were'replace'with'the'sharks'(cartilaginous'fish)'and'the'boney'fish.'o Sharks'and'boney'fish'had'heavier'and'more'efficient'jaws'that'opened'farther'allowing'for'more'affective'hunting.''o Beyond'their'similar'jaws,'there'is'a'pretty'big'division'between'sharks'and'boney'fish.'Sharks:'o The'early'jawed'fishes'that'died'out'had'a'cartilaginous'skeleton'(like'modern'sharks),'and'the'jawless'fish'o The'sharks'that'arose'from'them'even'had'hard'stronger'cartlidge'embedded'with'calcium'carbonate.'This'makes'a'light'but'very'strong'skeleton.'The'combination'of'this'with'a'very'strong'jaw'makes'them'top'predators'in'oceans.'o First'vertebrates'that'evolved'teeth'o Allow'both'predators'and'herbivores'to'chew'their'food'o Chewing'allows'animals'to'eat'larger'prey'items'and'aid'digestion'of'food'and'increase'nutrient'release'and'uptake'from'food.''o Not'embedded'in'jaw,'they'sit'ontop'of'the'jaw2'shark'teeth'o Shark'teeth'are'easily'lost'because'of'that'o Up'to'20'rows'of'teeth,'when'one'is'lost,'the'ones'behind'it'moves'up'o A'single'shark'can'loose'up'to'20k'teeth'in'its'life'time'o
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