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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
- Radial symmetry, bilateral symmetry, Pinworms Sea