01:119:115 Lecture Notes - Lecture 7: Amnion, Amphibian, Actinistia
15 Oct 2017
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Document Summary
Ancestral protest (metazoa) eumetazoa (radiata) bilateria (protostomia) . Larval stage - larvae exhibit bilateral symmetry. Adult stage - five part body structure (starfish) Water vascular - fluid-filled canals and chambers. All share a set of derived characteristics (at some point in life cycle, they had these characteristics) Notochord - firm, flexible, longitudinal supporting rod. Located between the gut and nerve chord. Functions as internal skeleton all chordate embryos, some adults. Dorsal, hollow nerve cord - all non-chordates animals have ventral, solid nerve cord. Develops into central nervous system via cephalization. Ancestor was probably a suspension feeder (have to live in water and filter out particles via gill slit) Muscular post-anal tail extends posteriorly beyond anus. Basal clades (groups of organisms that are the roots of phylogenetic trees) Characterized by having one set of hox genes - more developmentally complex. Chordate characteristics are most evident during embryonic stages. Adults are with backbone which can be made of bone or cartilage.
