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Chapter 3 Animal Architecture Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stages of development: Zygote, Blastula, Gastrula Types of cleavage: Radial (Regulative) v. Spiral (Mosaic) Symmetry: Aymmetry, Spherical Symmetry, Radial Symmetry, Bilateral Symmetry DEVELOPMENT Figure 3_05 Figure 3_03 Typical of echinoderms and chordates Typical of molluscs and annelids Figure 3_04 Animal Body Plans • Animal Symmetry – Symmetry • Correspondence of size and shape of parts on opposite sides of a median plane – Spherical symmetry • Any plane passing through center divides body into mirrored halves • Best suited for floating and rolling • Found chiefly among some unicellular forms • Rare in animals 9-6 Body Plans – Radial symmetry • Body divided into similar halves by more than 2 planes passing through longitudinal axis • Usually sessile, freely floating, or weakly swimming animals • No anterior or posterior end – Can interact with environment in all directions 9-7 Body – Bilateral Symmetry Plans • Organism can be divided along a sagittal plane into two mirror portions – Right and left halves • Much better fitted for directional (forward) movement • Associated with cephalization – Differentiation of a head region with concentration of nervous tissue and sense organs • Advantageous to an animal moving through its environment head first • Always accompanied by differentiation along an anteroposterior axis 9-8 Figure 3_01 Body Plans • Regions of bilaterally symmetrical animals – Anterior • Head end – Posterior • Tail end – Dorsal • Back side – Ventral • Front or belly side – Medial • Midline of body – Lateral • Sides 9-10 Body – Distal Plans • Parts farther from the middle of body – Proximal • Parts are nearer the middle of body – Frontal plane (coronal plane) • Divides bilateral body into dorsal and ventral halves – Sagittal plane • Divides body into right and left halves – Transverse plane (cross section) • Divides body into anterior and posterior portions 9-11 Figure 3_02 Anatomical terminology Or segmentation: serial repetition of similar body segments (metameres) along longitudinal axis METAMERISM 9-14 Deuterstome--“Second mouth”: 1) mouth forms from second opening 2) radial cleavage 3) coelom forms by outpocketing 4) regulative embryo; Echinoderms, Hemichordates, and tunicates, lancelets and vertebrates in Chordates Protostome—”Mouth first”: 1) mouth forms, then anus 2) spiral cleavage 3) coelom forms by splitting 4) mosaic embryo Two groups: Ecdysozoa—animals that molt & Lophotrochozoa— lampshells (phylum Brachiopoda), snails (phylum Mollusca), and worms (phylum Annelida) DEUTEROSTOME V. PROTOSTOME Figure 3_08 Acoelomate—planaria (phylum Platyhelminthes) Pseducoelomate—nematode (phylum Nematoda) Coelomate—oligochaete (phylum Annelida) BODY PLANS Figure 3_09 Epithelial—lines cavity or covers surface. Skin Connective—cells and matrix (fibers & ground substance). Blood, lymph, cartilage, bone Muscle—contractile. Skeletal, cardiac & smooth Nervous—excitable. Neurons & glia FOUR TISSUE TYPES Figure 3_10 ts of Metazoan – Epithelial Tissue Bodies• Sheet of cells that covers an internal or external surface • Avascular • Function – Protection – Absorption – Secretion 9-21 ts of Metazoan • Simple epithelia Bodies – Single layer of cells – Found in all metazoa • Stratified epithelia – 2 or more cell layers – Restricted to vertebrates • Separated from underlying tissues by a basement membrane 9-22 Figure 3_11a Found in lungs & frog skin Figure 3_11b Found in kidneys & glands Figure 3_11c Found lining intestine Figure 3_12c Found in skin and orifices ts of Metazoan Bodies • Connective Tissue – Widespread in body – Contains relatively few cells, many fibers, and a ground substance or matrix – 2 types of connective tissue proper In vertebrates – Loose connective tissue • Contains fibers and both fixed and wandering cells in a viscous fluid matrix – Dense connective tissues – Characterized by densely packed fibers and little matrix • Connective tissue also includes blood, lymph, cartilage, and bone 9-27 Figure 3_12a Figure 3_12d Guess where this is found Figure 3_13a Loose connective tissue Figure 3_13b Dense CT Figure 3_13c cartilage Figure 3_13d bone Metazoan Bodies • Muscular Tissue – – – – – Most abundant tissue in most animals Originates from mesoderm Muscle cell called a muscle fiber Specialized for contraction 3 types • Skeletal – Striated, unbranched, multinuclei, and voluntary • Cardiac – Striated, branched, 1-2 nuclei, involuntary • Smooth – No striations, unbranched, 1 nucleus, involuntary 9-34 Figure 3_14a Figure 3_14b Figure 3_14c Metazoan Bodies • Nervous Tissue • Specialized to receive stimuli and conduct impulses from one region to another • 2 basic cell types – Neurons • Structural and functional unit of nervous system – Neuroglia • Insulate and support neurons. 9-38 Figure 3_15 Neuron—Dendrites, soma & axon TRENDS IN SIZE AND METABOLIC RATES Figure 3_16 Figure 3_17