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Unformatted text preview: Animal: I ntroduction Animals are multicellular, aerobic heterotrophs that reproduce sexually and some asexually Outline: 1. Key concepts 2. Several characteristics of animals 3. Some terms 4. Classification of Animal Kingdom 5. Major Animal groups 6. Key Terms 7. Conclusions Key Concepts All animals are multielled heterotrophs Animals reproduce sexually or asexually Animals originated about 1.2 million years ago Comparisons of body plans of existing animals with fossils reveal that there were several trends in the evolutions of certain lineages The sponges are structurally simple animals without body symmetry Cnidarians have radial symmetry Bilateral symmetry is seen in animals more complex than the cnidarians and have developed organ systems Several characteristics of animals Multicellular Eukaryotes Their cells lack cell walls Heterotrophs That ingest their food Aerobic respiration Oxygen Most animals reproduce sexually With the diploid stage usually dominating the life cycle...
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- Spring '08