Chapter 32 - Chapter 32 An Introduction to Animal Diversity...

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Chapter 32 An Introduction to Animal Diversity Book Notes
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Overview: Welcome to Your Kingdom o The animal kingdom extends far beyond humans and other animals we may encounter Animal Characteristics o Animals are Heterotrophs that ingest their food o Animals are multicellular eukaryotes o Their cells lack cell walls o Their bodies are held together by structural proteins such as collagen o Nervous tissue and muscle tissue are unique to animals Reproduction and Development o Most animals reproduce sexually with the diploid stage usually dominating the life cycle o After a sperm fertilizes an egg the zygote undergoes cleavage, leading to the formation of a blastula o The blastula undergoes gastrulation resulting in the formation of embryonic tissue layers and a gastrula o Early embryonic development in animals
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The zygote of an animal undergoes a succession of mitotic cell divisions called cleavage Only one cleavage stage – the eight cell embryo – is shown here In most animals, cleavage results in the formation of a multicellular stage called a blastula. The blastula of many animals is a hollow ball of cells Most animals also undergo gastrulation, a rearrangement of the embryo in which one end of the embryo folds inward, expands, and eventually fills the blastocoels, producing layers of embryonic tissue: the ectoderm (outer layer) and the endoderm (inner layer) The blind pouch formed by gastrulation, called the archenteron, opens to the outside wia the blatopore The endoderm of the archenteron develops into the tissue lining the
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This note was uploaded on 03/25/2008 for the course BIOL 112 taught by Professor Mets during the Spring '08 term at Texas A&M University-Galveston.

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Chapter 32 - Chapter 32 An Introduction to Animal Diversity...

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