November 6-ch23 - November 6, 2007 Chapter 23 Diversity of...

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November 6, 2007 Chapter 23 Diversity of Invertebrates Invertebrate: Anything without a vertebral column Key features of animals Animals possess of all the following characteristics o Multicellularity o Heterotrophic o Most reproduce sexually o Cells lack a cell wall o Are motile at some point in life cycle o Are able to respond rapidly to external stimuli Anatomical features that mark branch points in animal evolution o Lack of tissues separates sponges from all other animals o Animals with tissues exhibit either radial or bilateral symmetry o Most bilateral animals have body cavities o Body cavities show either protostome or deuterostome development o Most animal phyla currently populating the earth were present by the Cambrian period (544 million years ago) o The scarcity of pre-Cambrian animal fossils o Systematists search for clues about evolutionary history of animals by examining features of Anatomy Embryological development DNA sequences o Certain features represesnt evolutionary miles stones Tissues Body symmetry Protostome and deuterostome development o These features mark major branching points on the animal evolutionary tree The appearance of Tissue
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This note was uploaded on 04/10/2008 for the course BIOLOGY 101 taught by Professor Beitch during the Spring '07 term at Quinnipiac.

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November 6-ch23 - November 6, 2007 Chapter 23 Diversity of...

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