ZOO 2090 Lecture 1: Chordata and Its Close Relatives
11 Sep 2017
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Zoology *2090 lecture 1: chordata and its close relatives. Retention of ancestral characters > phylogenetic inertia > history. Homologous characters: share a common ancestry/derived from the same ancestral structure (i. e. human hands, bird wings, flippers) Analogous characters: have the same function but not necessarily the same ancestry. Phylogeny: is a genealogy (historical relationships) of species or higher taxa. Monophyletic group: includes most recent common ancestor and all its descendants. Classification levels: kingdom > phylum > class > order > family > genius > species. Together, three phyla make up deuterostoma (secondary mouth), with protostoma (first mouth) as its sister group. Proboscis is used for locomotion and feeding (eat sediments or filter feed: pterobranhcs. Marine deuterostomes with radial symmetry as adults, bilateral symmetry as larvae. Was considered closely related to vertebrates because they share segmented trunk mucles. Filter feeding by pharyngeal filtration system driven by cilia. No differentiated brain, special sense organs or heart.
