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ANIMALS

ANIMALS. The Nature of Animals. 34.1. Vertebrate An animal with a backbone Invertebrate An animal without a backbone. CHARACTERISTICS. Animals are: Multicellular Heterotrophic Lack cell walls Most reproduce sexually Most have movement. Multicellular Organization.

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ANIMALS

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  1. ANIMALS The Nature of Animals

  2. 34.1 • Vertebrate • An animal with a backbone • Invertebrate • An animal without a backbone

  3. CHARACTERISTICS • Animals are: • Multicellular • Heterotrophic • Lack cell walls • Most reproduce sexually • Most have movement

  4. Multicellular Organization • Body of adult human contains 50 trillion cells. • Cells of multicellular organisms do not live independently. • They cooperate and work together… • Cells – tissues – organs – organ systems – organism • Specialization is the adaptation of a cell for a particular function. • Cell junctions are connections between cells. • Cell junctions hold the cells together as a unit and in this way form tissues.

  5. Heterotrophy • Ingestion is the taking in of organic material. • Digestion then takes place: • nutrients are extracted

  6. Sexual Reproduction and Development • Sexual: • Most animals reproduce sexually. • Allows for more genetic variability.

  7. Sexual Reproduction and Development • Asexual: • Hydra – budding • Sponges – internal budding (gemmules) • Planaria – fragmentation (head / tail), although most reproduce sexually • Echinoderms (starfish) – regeneration • zygote: 1st cell of a new individual (diploid) • Will undergo repeated mitotic divisions • Differentiation: cells become different from each other, i.e., blood, bone, skin, muscle… • The process of differentiation is the path to cell specialization.

  8. Movement • Attachment: • Barnacles attach to a surface, aka substrate. • Life Cycle: • Egg – larva – then leaves parent's shells, spends youth swimming, sticks to rocks for all adulthood.

  9. Neurons LINK Neurons are cells of nervous tissue. Nervous tissue… through electrical signals (impulses), animals detect stimuli. Muscle tissue allows animals to respond to the stimuli.

  10. Origin and Classification First animals probably originated in the sea. They probably evolved from protists. Protists are both heterotrophic and eukaryotic.

  11. Origin and Classification Cell specialization during early period of evolution… • Colonial protists may have lost their flagella as individual cells within the colony became more specialized. • They may have been similar to modern colonial protists that do show some degree of cell specialization. • In these species, the gametes are distinct from non-reproductive cells.

  12. Origin and Classification A similar division of labor in early protists may have been the 1st step toward multicellularity. Many taxonomists recognize 30+ animal phyla. Some phyla contain a very small # of species.

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