3. Vertebrates post

3. Vertebrates post - Vertebrates Phylogeny of...

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Vertebrates
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Phylogeny of Deuterostomes Deuterostomes Echinoderms Chordata 2 groups lack vertebrae 2 groups lack jaws Fins vs legs Amniotic eggs Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Milk Amniotic egg Legs Lobed fins Lungs or lung derivatives Jaws, mineralized skeleton Vertebral column Head Brain Notochord Ancestral deuterostome Echinodermata (sister group to chordates) Urochordata (tunicates) Cephalochordata (lancelets) Myxini (hagfishes) Cephalaspidomorphi (lampreys) Chondrichthyes (sharks, rays, chimaeras) Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Dipnoi (lungfishes) Amphibia (frogs, salamanders) Reptilia (turtles, snakes, crocodiles, birds) Mammalia (mammals) Figure 34.2
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Chordata Anatomical features (anytime during life-cycle often embryonic) Notocord Dorsal hollow nerve cord Pharyngeal slits Muscular postanal tail
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Anatomical Features Notocord Embryonic structure for most Flexible rod located between the digestive tube and the nerve cord Provides skeletal support Fate Persist in the adult of some invertebrate chordates Replaced by more complex skeleton and only remnants remain Dorsal, hollow nerve cord Develops from a plate of the ectoderm that rolls into a hollow tube Becomes the brain and spinal cord Other animals generally have solid nerve cords located on the ventral surface
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Anatomical Features Pharyngeal slits Located in the pharynx Slits that are open to the outside environment Allow water that enters and exit the mouth without going through the entire complete digestive tract Functions • Suspension feeding for invertebrate chordates • Respiratory organs in some aquatic species • Jaw support and structures related to hearing Muscular, postanal tail Tail extends beyond the anus Contains skeletal components and muscular movement
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Subphylum Urochordata Tunicates or sea squirts Uses tail muscles and notochord to swim during larval stage to find suitable location Metamorphosis occurs and it looses many of its chordate characteristics Sessile marine animals attached to permanent structures Body plan Covered by a cellulose-like tunic Organs rotate 90 degrees (U shaped) Suspension feeding using incurrent and excurrent siphons and pharyngeal slits
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Subphylym Cephalochordata Lancets Live in sand on bottom of sea Body plan All anatomical characteristics present
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3. Vertebrates post - Vertebrates Phylogeny of...

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