power4 - 10/15/2008 1 Chordates include the Vertebrates as...

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10/15/2008 1 1 Chordates include the Vertebrates as their most successful and diverse branch, along with some small ancient precursors 2 What are the essential features of the chordates? What advantage did these features give them over other aquatic forms of life? 3 The tunicates or sea squirts seem (Urochordates) like unlikely chordates. What is missing? 4 Adult tunicates are sessile, tubular organisms that feed by filtering food from water siphoned through a basket-like pharynx 5 Water is moved through the pharyngeal “basket” via incurrent and excurrent siphons; the earliest chordates may have been sessile as adults like their early echinoderm cousins 6 Tunicate larvae are motile, with bilateral symmetry and a long, muscular, post-anal tail supported by a narrow, flexible notochord
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10/15/2008 2 7 Other early chordates are bilaterally symmetrical as larvae and adults, and may have evolved from precocious larvae. 8
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This note was uploaded on 02/10/2010 for the course BSC 2010 taught by Professor Essig during the Spring '10 term at University of Southern Maine.

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power4 - 10/15/2008 1 Chordates include the Vertebrates as...

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