BIO SCI 94 Chapter Notes - Chapter 35: Cambrian Explosion, Marsupial, Viviparity

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

The deuterostomes include the largest-bodied and some of the most morphologically complex of all animals. Phylogenies based on molecular evidence have confirmed the monophyly of deuterostomes - four phyla: Hemichordates or acorn worms burrow in marine sand/muds and make living by deposit feeding or suspension feeding. Xenturbella - long genus w/ two wormlike species that are small & ciliated. Chordates - include vertebrates including hagfish, lampreys, sharks and rays, bony fish, amphibians, mammals, and reptiles & birds. Echinodermata are large and diverse, but exclusively marine. Remarkable event occurred early in the evolution of echinoderms: the origin of five-sided radial symmetry called pentaradial symmetry in adults. Radially symmetric animals have no head, so tend to interact with environment in all directions instead of one. Endoskeleton - hard structure located just inside a thin layer of epidermal tissue, which provides protection and support. Unique morphological feature - water vascular system: series of branching, fluid-filled tubes and chambers.