UT Arlington BIOL 3454 - CHORDATA (4 pages)

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Lecture number:
Lecture Note
University of Texas at Arlington
Biol 3454 - General Zoology

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BIOL 3454 1st Edition Lecture 28 Chordata a characteristics i notochord ii dorsal hollow nerve cord iii pharyngeal gill slits or pouches iv postanal tail v endostyle in floor of pharynx vi notochord 1 flexible rodlike becomes the spinal column in vertebrates 2 hydrostatic muscles attach to it as it can bend w o shortening vii dorsal hollow nerve cord 1 hollow dorsal end usually enlarged to form a brain in chordates 2 from endodermal ridge to top of body viii pharyngeal pouches or slits 1 pharyngeal cavity to outside 2 give rise to several structures later in evolutionary development 3 evolved as a filter feeding apparatus 4 gills come later ix postanal tail 1 mobility 2 evolved for propulsion in aquatic environments 3 added to body behind digestive tract x endostyle or thyroid gland 1 all chordates have but nothing else does last 10 years 2 evolved to aid in filter feeding 3 secretes proteins later as a glad secretes hormones b subphylum urochordata i tunicates or sea squirts ii 1600 species iii Surrounding by a tough nonliving tunic made of cellulose iv Adults are highly specialized and resemble sponges but larvae have all chordate characteristics v During metamorphosis some characteristics are lost tail and notochord disappear dorsal verve cord becomes reduced to a single ganglion vi 3 classes 1 Ascidiavea most diverse and common 2 Appendicularia 3 Thaliacea vii Solitary colonial or compound viii Form and function These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 1 2 3 4 Adults spherical or cylindrical forms Inner membrane called the mantle 2 siphons internal oral and excurrent atrial Water flows into the oral siphon through pharynx then passes slits in atrial cavity then out the strial siphon 5 Circulatory system of a ventral heart and two large lateral vessels 6 Bloods flows one way then reverses 7 Blood has a high proportion of weird elements 8 One big nerve

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