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Explore the fascinating world of animal diversity, focusing on their multicellular, heterotrophic nature, and lack of cell walls. Discover the significance of body symmetry types—radial and bilateral symmetry—along with terminology such as dorsal, ventral, anterior, and posterior. Understand the processes of fertilization, cleavage, and gastrulation leading to varied developmental patterns, including protostomes and deuterostomes. Learn how these adaptations contribute to specialization and functionality in animal systems, paving the way for the incredible variety of life forms.
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Multicellular Heterotrophic Lack cell walls Sexual Reproduction Movement Specialization – adaptation for a cell for a particular function Cells tissues organs organ systems
Dorsal – top Ventral – bottom Anterior – head Posterior - Tail Body Structure
Asymmetry – no symmetry 23.2 Animal Diversity Body Symmetry • Radial – arrangement of body parts around a central axis • - top & bottom, no front, back, or right & left sides • Bilateral symmetry – 2 similar halves on either side of a central plane
23.2 Animal Diversity Radial Symmetry – allows for organism to take in stimuli from all sides
23.2 Animal Diversity Bilateral Symmetry – adaptation for movement
concentration of sensory & brain structures in the anterior region 23.2 Animal Diversity Cephalization No-cephalization
Gamete + Gamete = Zygote Sperm membrane fuses with egg membrane causes an electrical shock that blocks entry by other sperm Sperm nucleus merges with egg nucleus 23.2 Animal Diversity Fertilization
Rapidly increases # of cells, but cells do not grow in size Increases surface area-to-volume ratio Continues until they form a hollow ball of cells – blastula Central cavity - blastocoel 23.2 Animal Diversity Cleavage – cell divisions of the zygote immediately following fertilization
Blastopore – infolded region - will function as the gut Gastrula – multilayered embryo Deep cavity is formed – archenteron – embryonic stem cells Ectoderm – outer germ (cell) layer Skin, hair, etc. Endoderm – inner germ layer Digestive system Mesoderm – layer between ectoderm & endoderm Muscular and Skeletal systems 23.2 Animal Diversity Gastrulation – blastula collapses inward
Protostomes – blastopore first develops into a mouth Deuterostomes – blastopore first develops into anus 23.2 Animal Diversity Patterns of Development
Acoelomates – body cavity is absent Flatworms Pseudocoelomate – mesoderm lines the fluid-filled coelom (body cavity) Coelomates – mesoderm lines the body cavity and surrounds and supports the gut 23.2 Animal Diversity Types of Body Cavities