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Characteristics of Animals

Characteristics of Animals. Section 27.1. Features of Animals: # 1: Heterotrophy & Mobility. Animals cannot make their own food Most animals move to find food Food is digested internally Animals have the ability to make rapid, complex movements.

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Characteristics of Animals

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  1. Characteristics of Animals Section 27.1

  2. Features of Animals:# 1: Heterotrophy & Mobility • Animals cannot make their own food • Most animals move to find food • Food is digested internally • Animals have the ability to make rapid, complex movements

  3. Features of Animals, con’t:# 2: Multicellularity & Tissues • All animals are made of many specialized cells • Animals are the only multicellular group without cell walls • All cells are roughly the same size, regardless of the size of the animal • Similar cells are organized into functional groups called tissues

  4. Features of Animals, con’t:# 3: Diploidy & Sexual Reproduction • Adults cells are diploid – have 2 copies of each chromosome, 1 from each parent • Haploidgametes (sex cells with 1 set of chromosomes) unite to form offspring • The zygote (fertilized egg) is diploid • This allows for genetic diversity

  5. Features of Animals, con’t:# 4: Blastula Formation • The zygote divides to form a hollow ball – the blastula • Cells in the blastula develop three layers which then develop into different structures: • Ectoderm: skin, nervous system • Endoderm: digestive & respiratory systems • Mesoderm: skeleton, muscular, circulatory, reproductive & excretory systems

  6. Animal Body Plans:# 1: Symmetry • Asymmetrical – irregular in shape (sponges) • Radial symmetry – like the spokes of a wheel (sea anemone) • Bilateral symmetry – two equal sides (humans) • right & left sides • dorsal (back) & ventral (belly) • anterior (head) & posterior (tail)  cephalization

  7. Animal Body Plans, con’t:# 2: Internal Body Cavity • Found in bilaterally symmetrical animals • Coelom – the body cavity – fluid-filled space between body wall & gut; protects the internal organs • Three plans: • Acoelomate – no coelom • Pseudocoelomate – body cavity between the mesoderm and endoderm – “false coelom” • Coelomate – cavity within mesoderm; allows for greater movement

  8. Animal Body Plans, con’t:# 3: Segmentation • Segments are repeating body units • All higher animals have some degree of segmentation (vertebrae)

  9. Kinds of Animals • 35 phyla • Often divided into 2 major groups: • Invertebrates (without backbones) • Vertebrates (with backbones)

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