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Unformatted text preview: - Most animal phyla appear during Cambrian explosion Animals- Diversity- 75% are insects- 30% are beetles- 5% are vertebrates- 1% are mammals- Reproduction- Most reproduce sexually- Diploid stage dominates life cycle- Flagellated sperm; large non-motile eggs- Development- Zygote undergoes cleavage; forms hollow ball (blastula)- Blastula then develops into gastrula- Lining of gastrula: endoderm, exterior cells: exoderm- Hox genes- Master regulatory genes that dictate developing body- Highly conserved; linear correlation between body axis and chromosomal position- Small mutations lead to big changes in form- Gene duplications provide greater anatomical complexity- Body Plans- Symmetry- Radial symmetry- Bilateral symmetry- Tissues- Diplobastic- Exoderm- Endoderm- Triplobastic- Exoderm- Endoderm- Mesoderm- Specialized tissues:- Muscles- Neural- Body Cavities- Coelem: body cavity- Protostome/Deuterostome- Protostome: Mouth- Deuterostome: Anus...
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