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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 32 An Overview of Animal Diversity Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Seatwork 2 • Why is it important to study zoology? (5 sentences) (10 points) Overview: Welcome to Your Kingdom • The animal kingdom extends far beyond humans and other animals we may encounter • Scientists have identified 1.3 million living species of animals © 2011 Pearson Education, Inc. Figure 32.1 Concept 32.1: Animal are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers • There are exceptions to nearly every criterion for distinguishing animals from other life-forms • Several characteristics, taken together, sufficiently define the group © 2011 Pearson Education, Inc. Nutritional Mode • Animals are heterotrophs that ingest their food © 2011 Pearson Education, Inc. Cell Structure and Specialization • Animals are multicellular eukaryotes • Their cells lack cell walls • Their bodies are held together by structural proteins such as collagen • Nervous tissue and muscle tissue are unique, defining characteristics of animals • Tissues are groups of cells that have a common structure, function, or both © 2011 Pearson Education, Inc. Reproduction and Development • Most animals reproduce sexually, with the diploid stage usually dominating the life cycle • After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage • Cleavage leads to formation of a multicellular, hollow blastula • The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues © 2011 Pearson Education, Inc. Figure 32.2-3 Zygote Cleavage Blastocoel Cleavage Eight-cell stage Blastula Cross section of blastula Gastrulation Blastocoel Endoderm Ectoderm Archenteron Cross section of gastrula Blastopore • Many animals have at least one larval stage • A larva is sexually immature and morphologically distinct from the adult; it eventually undergoes metamorphosis • A juvenile resembles an adult, but is not yet sexually mature © 2011 Pearson Education, Inc. Figure 32.4 1.5 cm (a) Mawsonites spriggi 0.4 cm (b) Spriggina floundersi Figure 32.5 Concept 32.3: Animals can be characterized by “body plans” • Zoologists sometimes categorize animals according to a body plan, a set of morphological and developmental traits © 2011 Pearson Education, Inc. Symmetry • Animals can be categorized according to the symmetry of their bodies, or lack of it • Some animals have radial symmetry, with no front and back, or left and right © 2011 Pearson Education, Inc. Figure 32.7 (a) Radial symmetry (b) Bilateral symmetry • Two-sided symmetry is called bilateral symmetry • Bilaterally symmetrical animals have – – – – A dorsal (top) side and a ventral (bottom) side A right and left side Anterior (head) and posterior (tail) ends Cephalization, the development of a head © 2011 Pearson Education, Inc. Tissues • Animal body plans also vary according to the organization of the animal’s tissues • Tissues are collections of specialized cells isolated from other tissues by membranous layers • During development, three germ layers give rise to the tissues and organs of the animal embryo © 2011 Pearson Education, Inc. • Ectoderm is the germ layer covering the embryo’s surface • Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron © 2011 Pearson Education, Inc. • Sponges and a few other groups lack true tissues • Diploblastic animals have ectoderm and endoderm – These include cnidarians and comb jellies • Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians – These include flatworms, arthropods, vertebrates, and others © 2011 Pearson Education, Inc. Figure 32.8 (a) Coelomate Coelom Digestive tract (from endoderm) Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) (b) Pseudocoelomate Body covering (from ectoderm) Pseudocoelom Digestive tract (from endoderm) Muscle layer (from mesoderm) (c) Acoelomate Body covering (from ectoderm) Tissuefilled region (from mesoderm) Wall of digestive cavity (from endoderm) Figure 32.8a (a) Coelomate Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Figure 32.8b (b) Pseudocoelomate Body covering (from ectoderm) Pseudocoelom Digestive tract (from endoderm) Muscle layer (from mesoderm) Figure 32.8c (c) Acoelomate Body covering (from ectoderm) Tissuefilled region (from mesoderm) Wall of digestive cavity (from endoderm)