9-1 CHAPTER 9 Architectural Pattern of an Animal

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9-3 New Designs for Living Zoologists recognize 34 major phyla of living multicellular animals Zoologists recognize 34 major phyla of living multicellular animals Survivors of around 100 phyla that appeared 600 million years ago during Cambrian explosion Survivors of around 100 phyla that appeared 600 million years ago during Cambrian explosion

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9-5 Animal Body Plans Animal Symmetry Animal Symmetry Symmetry Symmetry Correspondence of size and shape of parts on opposite sides of a median plane Correspondence of size and shape of parts on opposite sides of a median plane Spherical symmetry Spherical symmetry Any plane passing through center divides body into mirrored halves Any plane passing through center divides body into mirrored halves Best suited for floating and rolling Best suited for floating and rolling Found chiefly among some unicellular forms Found chiefly among some unicellular forms Rare in animals (unicellular) Rare in animals (unicellular)

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9-7 Radial symmetry Radial symmetry Body divided into similar halves by more than 2 planes passing through longitudinal axis Body divided into similar halves by more than 2 planes passing through longitudinal axis Usually sessile, freely floating, or weakly swimming animals Usually sessile, freely floating, or weakly swimming animals Examples: jellyfish, sea urchin Examples: jellyfish, sea urchin No anterior or posterior end No anterior or posterior end Can interact with environment in all directions Can interact with environment in all directions Animal Body Plans

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9-8 Bilateral Symmetry Bilateral Symmetry Organism can be divided along a sagittal plane into two mirror portions Organism can be divided along a sagittal plane into two mirror portions Right and left halves Right and left halves Much better fitted for directional (forward) movement Much better fitted for directional (forward) movement Example: Most vertebrates Example: Most vertebrates Associated with cephalization Associated with cephalization Differentiation of a head region with concentration of nervous tissue and sense organs (brain) Differentiation of a head region with concentration of nervous tissue and sense organs (brain) Animal Body Plans

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Regions of bilaterally symmetrical animals Regions of bilaterally symmetrical animals Anterior Anterior Head end Head end Posterior Posterior Tail end Tail end Dorsal Dorsal Back side Back side Ventral Ventral Front or belly side Front or belly side Medial Medial Midline of body Midline of body Lateral Lateral Sides Sides Animal Body Plans

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Distal Distal Parts farther from the middle of body Parts farther from the middle of body Proximal Proximal Parts are nearer the middle of body Parts are nearer the middle of body Frontal plane (coronal plane) Frontal plane (coronal plane) Divides bilateral body into dorsal and ventral halves Divides bilateral body into dorsal and ventral halves Sagittal plane Sagittal plane Divides body into right and left halves Divides body into right and left halves Transverse plane (cross section) Transverse plane (cross section) Divides body into anterior and posterior portions Divides body into anterior and posterior portions Animal Body Plans

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Developmental Origins in Triploblasts Body Plans Triploblastic animals (have 3 germ layers) Triploblastic animals (have 3 germ layers) Ectoderm, endoderm, mesoderm Ectoderm, endoderm, mesoderm Diploblastic animals (have 2 germ layers) Diploblastic animals (have 2 germ layers) no mesoderm no mesoderm

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display A Complete Gut Design and Segmentation Metamerism (Segmentation) Metamerism (Segmentation) Serial repetition of similar body segments along longitudinal axis of body Serial repetition of similar body segments along longitudinal axis of body Each segment is a metamere Each segment is a metamere Permits greater body mobility and complexity of structure and function Permits greater body mobility and complexity of structure and function Annelids, Arthropods, Chordates Annelids, Arthropods, Chordates

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Ectoderm - outer epithelial tissue, nervous tissue Endoderm - digestive tissue, inner epithelial tissue Mesoderm - circulatory tissue, skeletal muscle, reproductive and bone tissue