Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Animal Architecture

DEVELOPMENT Stages of development: Zygote, Blastula, Gastrula Types of cleavage: Radial (Regulative) v. Spiral (Mosaic) Symmetry: Aymmetry, Spherical Symmetry, Radial Symmetry, Bilateral Symmetry

Figure 3_05

Figure 3_03 Typical of echinoderms and chordates Typical of molluscs and annelids

Figure 3_04

9-6 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

9-7 –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 Animal Body Plans

9-8 –Bilateral Symmetry 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 Animal Body Plans

Figure 3_01

9-10 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 Animal Body Plans

9-11 –Distal 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 Animal Body Plans

Figure 3_02 Anatomical terminology

METAMERISM Or segmentation: serial repetition of similar body segments (metameres) along longitudinal axis

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DEUTEROSTOME V. PROTOSTOME 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)

Figure 3_08

BODY PLANS Acoelomate—planaria (phylum Platyhelminthes) Pseducoelomate—nematode (phylum Nematoda) Coelomate—oligochaete (phylum Annelida)

Figure 3_09

FOUR TISSUE TYPES 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

Figure 3_10

9-21 –Epithelial Tissue Sheet of cells that covers an internal or external surface Avascular Function –Protection –Absorption –Secretion Componen ts of Metazoan Bodies

9-22 Simple epithelia –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 Componen ts of Metazoan Bodies

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

9-27 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 Componen ts of Metazoan Bodies

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

9-34 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 Componen ts of Metazoan Bodies

Figure 3_14a

Figure 3_14b

Figure 3_14c

9-38 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. Componen ts of Metazoan Bodies

Figure 3_15 Neuron—Dendrites, soma & axon

TRENDS IN SIZE AND METABOLIC RATES

Figure 3_16

Figure 3_17