Chordate Diversity 1

Chordate Diversity 1 - Chordate Diversity 1 What are...

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Chordate Diversity 1 What are Chordates? - Pleisiomorphic (ancestral) Characters: - All chordates exhibit these traits at some point during ontogeny. - Some species only exhibit these traits during embryonic development 1. Notochord - Skeletal support - Flexible rod made of fluid-±lled cells - Becomes part of spine in higher vertebrates 2. Dorsal, hollow nerve chord - Develops into CNS (Central Nerve System) 3. Pharyngeal slits - Filter-feeding devices - Respiration (gills) 4. Muscular post-anal tail - Propulsion (Aquatic) Lancelets and Tunicates - Relatively uncommon - Lancelets - Fish-like - Use cilia to ±lter-feed - Adults have all 4 chordate characters - Tunicates - aka sea squirts - Larvae have all 4 chordate characters
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- Once they become adults the only chordate character they have are the slits. First major milestone is the development of a head. (Craniates) - “Hag±shes” (not a true “±sh”) - Evolution of craniates (chordates w/ heads) - Cartilaginous skull - Lack jaws and vertebrae - Produce slime to deter predators
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Chordate Diversity 1 - Chordate Diversity 1 What are...

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