Chapter 31 - Chapter 31 Chordates (chordata)...

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Chapter 31 Chordates (chordata) Cephalochordata Urochordata Vertebrata All are deuterostomes Second opening is mouth, etc 45k species Characteristics Notochord – dorsal supporting rod, becomes vertebral column Nerve cord – dorsal fluid filled tube, becomes spinal cord Pharyngeal puches – only present during embryonic development in most vertebrates Tail – in embryo, not always adult Cephalochordata : Lancelets (25 sp) Notochord persists and is never replace by a vertebral column Urochordata : Tunicates Sea squirts Vertebrata : 43.7 species Vertebrate skeleton is living tissue that grows with animal Main axis of internal jointed skeleton consists of vertebral column and a skull that encloses the brain High degree of cephalization is accompanied by complex sense organs Evolution of jaws and predation Aminion allows reproduction on land (amniotic fluid)
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Features: Living endoskeleton with vertebral column Closed circulatory system Complete digestive tract Large coelom Paired appendages Efficient respiration and excretion High degree of cephalization Adapted to active lifestyles Sexes generally separate Fish : Fishes are aquatic, gill-breathing vertebrates that usually have fins and scale-covered skin Jawless fish (Agnatha): Ostracoderms – earliest vertebrate fossils, now extinct Lampreys and hagfishes are modern-day jawless fish that lack a bony skeleton -Filter feeders, scavengers, or parasitic Gnathostomates have jaws (tooth bearing bones in head)
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This note was uploaded on 12/03/2009 for the course ENGLIT 15514 taught by Professor Satyavolu during the Fall '09 term at Pittsburgh.

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Chapter 31 - Chapter 31 Chordates (chordata)...

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