Integrated Principles of Zoology is a college text adaptable to any introductory course in zoology. This eleventh edition, as with previous editions, describes the diversity of animal life and the fascinating adaptations that enable animals to inhabit nearly all conceivable ecological niches. We retain in this revision the basic organization of the eleventh edition and its distinctive features, especially emphasis on the principles of evolution and zoological science. Also retained are several pedagogical features that have made previous editions easily accessible to students: opening chapter dialogues drawn from the chapter's theme; chapter summaries and review questions to aid student comprehension and study; accurate and visually appealing illustrations; in-text derivations of generic names; chapter notes and essays that enhance the text by offering interesting sidelights to the narrative; and an extensive glossary providing pronunciation, derivation, and definition of terms used in the text.

New to the Twelfth Edition

Many of the changes in this edition were guided by the suggestions of 49 instructors who read and commented on sections of the eleventh edition. For the eleventh edition, the vertebrate chapters of Part Three, and several chapters on functional systems (Part Four) were revised by invited contributors, all experienced zoologists who were solicited for their interest and expertise in the subject matter of specific chapters. This twelfth edition continues to benefit from their participation. In general, we revised all chapters to make the text current while eliminating excessive detail, and placed more emphasis on experimentation and comparative studies in zoology.

CHAPTER ORGANIZATION

• Order of chapters in Parts One and Two has been maintained as in the eleventh edition. The presentation is streamlined by discussing basic chemistry in the context of the origin of life.
• Several chapters in Part Three have been reorganized. Because evidence is strong that lophophorate phyla and Chaetognatha are protostomes, separate chapters for each of these are not justified; therefore, material on these phyla has been moved to a single chapter covering all smaller phyla of coelomate protostomes (Chapter 21). Removal of chaetognaths from the chapter covering hemichordates made that chapter quite short, and accordingly, hemichordates are now covered in the same chapter as echinoderms, their closest relatives.

NEW PEDAGOGY

• Throughout the text we updated references, revised or replaced many illustrations, and rewrote many of the Review Questions to provoke thought and reduce emphasis on rote memorization.
• Suggested Internet topics are added at the end of each chapter; hyperlinks are available on this text’s Online Learning Center web site at www.mhhe.com/zoology.
• The art inside the front cover has been completely revised to depict phylogenetic relationships consistent with the Lophotrochozoa/Ecdysozoa hypothesis and other phylogenetic relationships based on sequence analysis of DNA.

The principal revisions in each chapter are explained below.

Part One: Introduction to the Living Animals

• Chapter 2, The Origin and Chemistry of Life, now introduces the important concept of symbiogenesis in the context of origin of eukaryotic cells. A review of basic chemistry (atoms, elements, and molecules; bonding theory; acids, bases, salts, and buffers) is available for reference; it will be found at our Online Learning Center web site: www.mhhe.com/zoology.

Part Two: Continuity and Evolution of Animal Life

• Chapter 5, Genetics: A Review, features new art, including a revised meiosis figure that includes homologous chromosomes in synapsis during prophase of meiosis I and clarifications of 5’ and 3’ ends of RNA and DNA, indicating direction of synthesis. We have added new material on publication of the draft sequence of the human genome and its implications, as well as an explanation of proteomics.
• In Chapter 6, Organic Evolution, we have added information on new fossil discoveries from China. We relate the issue of gradualism to new work in developmental genetics.
• Chapter 7, The Reproductive Process, was revised extensively in the eleventh edition. Notes on contraception were updated to reflect new trends.

Part Three: Diversity of Animal Life

• Chapter 10, Classification and Phylogeny of Animals, has been reorganized. We present species concepts and diagnosis and then proceed to higher-level taxonomy, rather than vice versa, as in the eleventh edition. We revised coverage of subspecies and added the process of species recognition. A boxed essay has been added to describe how phylogenies are constructed from DNA sequences, and a new taxonomic system called PhyloCode is explained.
• Chapter 11, Protozoan Groups, was completely reorganized in an effort to make it consistent with current classification of unicellular eukaryotes. Traditional taxa such as Sarcomastigophora, Sarcodina, Mastigophora, Zoomastigophora, and Phytomastigophora are all discarded. Flagellated forms that we discuss are distributed among separate phyla: Retortamonada, Axostylata, Chlorophyta, Euglenozoa, and Dinoflagellata. Protozoologists now disperse ameboid forms into numerous lineages, and it is impractical for us to place them all in formal taxa; therefore, we simply use an informal heading “Amebas” to introduce some of the most important ones. The section on phylogeny was rewritten to reflect current evidence, including the likelihood of secondary symbiogenesis in origins of several groups.
• In discussing the phylogeny of Mesozoa in Chapter 12, we note that molecular evidence supports a relationship with flatworms. The description of Hexactinellida was completely rewritten, and a new figure depicting their structure is included.
• Chapter 13, Radiate Animals, underwent several important revisions. Most noticeable to users of earlier editions is a preference for use of Octocorallia over Alcyonaria for this anthozoan subclass. Because members of the subclass always have eight tentacles, we believe that Octocorallia is easier for students to remember. In addition, the discussion of cnidarian phylogeny was rewritten to include evidence from Hox genes and sequence data that Anthozoa is basal for the phylum. A new cladogram reflects this relationship.
• In Chapter 14, Acoelomate Animals, the description of both form and function in Nemertea and phylogeny of flatworms were rewritten.
• Chapter 15, Pseudocoelomate Animals, was completely reorganized. We hope that placing all animals with a common body plan in the same chapter will be helpful for students, rather than separating pseudocoelomate lophotrochozoans from pseudocoelomate ecdysozoans in separate chapters. Thus, phyla in each superphylum were grouped together under appropriate headings (see also Chapter 21). Furthermore, because Nematoda is the largest and most important of all pseudocoelomate phyla, their coverage was moved to the beginning of the chapter. Recognizing molecular evidence of a rotifer-acanthocephalan affinity, coverage of Acanthocephala was moved to follow immediately after Rotifera.
• Chapter 16, Molluscs, was not changed extensively. A note on the evolution of eyes in animals was added, with the observation that all animals with eyes apparently share two conserved genes: Pax 6, the “master control gene for eye morphogenesis,” and the gene encoding rhodopsin, a visual pigment. The eyes of cephalopod molluscs are amazingly similar to those of vertebrates. Although this has long been considered an astonishing example of convergence, both groups must have inherited the genes from a common ancestor, and thus their eyes would be homologous.
• Chapter 18, Arthropods, is an introduction to Arthropoda and a more detailed coverage of Chelicerata. In this chapter, many sections on spiders, scorpions, and harvestment were rewritten and revised.
• Chapter 19, Aquatic Mandibulates, benefits from much new art. The phylogeny section in this chapter was rewritten and includes a discussion of how biramous limbs in Crustacea probably arose by a mutation resulting in a modulation of Distal-less gene expression.
• Chapter 20, Terrestrial Mandibulates, is a large chapter because insects are a large group. There were many small rewrites and additions, including the discussion and illustration of sucking mouthparts. The phylogeny discussion was heavily rewritten, including roles of Hox genes and Distal-less gene and the evolution of flight.
• Chapter 21, Smaller Protostome Phyla, was extensively reorganized, as in Chapter 15, grouping lophotrochozoan and ecdysozoan phyla under their appropriate headings. Lophophorate phyla and Chaetognatha were brought into this chapter because present evidence lends little justification to covering them in separate chapters. Significant changes in the phylogeny discussion were required.
• Chapter 22, Echinoderms and Hemichordates, now includes all deuterostomes other than chordates. After removal of chaetognaths from the chapter covering hemichordates, a very short chapter resulted; therefore, hemichordates were moved to join Echinodermata.
• Chapter 23, Chordates, underwent many changes throughout, incorporating new ideas about chordate origins and character evolution, primarily from new fossil finds in China, molecular phylogenetics, and studies of developmental biology. Specifically, we modified and added figures, revised characteristics of chordates and vertebrates, revised discussion of hypotheses of origins of chordates and vertebrates, and added a discussion on Hox genes. Discussions of conodonts, ostracoderms, origin of jaws, and origin of paired appendages were revised to better emphasize critical concepts and include more recent information.
• Coverage of the ecology of amphibian declines in the world is increased in Chapter 25, Early Tetrapods and Modern Amphibians.
• The title of Chapter 26, Amniote Origins and Reptilian Groups, was changed to better reflect expanded coverage of derived features of amniotes, including the amniote egg. Relationships of major groups were updated, especially showing that snakes and amphisbaenians evolved from a lizard-like ancestor. Discussions of dinosaur behavior and extinction, snake feeding methods, snakebite statistics, and ectothermy were revised. A new illustration of a snake skull was added to show the extreme mobility of their head bones.
• Chapter 27, Birds, incorporates material on new fossil dinosaur-bird finds and their significance to flight. The section on mating systems was also modified.
• In Chapter 28, Mammals, coverage on synapsid evolution has been expanded and supporting artwork is modified. We added a section on whale evolution, revised the section on the fermentation system, and updated coverage of human evolution, incorporating information from recent fossil finds and analyses. Coverage of evolution of reproductive systems was changed extensively, including evidence that the chorioallantoic placenta of placental mammals evolved in a common ancestor of marsupials and placentals, and was secondarily lost in marsupials.

Part Four: Activity of Life

• In Chapter 29, Support Protection and Movement, we clarified the role of exercise in differential stimulation of fast and slow fiber types, and we updated the microanatomy and physiology of skeletal muscle contraction.
• We elaborated on the concept of homeostatic setpoint in Chapter 30, Homeostasis, and sections on the role of urea in osmoregulation of elasmobranchs and in urine concentration by mammals were revised. Also revised were coverage of aldosterone secretion, glomerular tubular secretion, ADH mechanism of action, and countercurrent multiplication.
• Chapter 31, Internal Fluids and Respiration, includes revisions on excitation and control of heart function, structure and function of the arterial system, respiration in birds, regulation of respiration, and transport of respiratory gases in mammals.
• In Chapter 32, Digestion and Nutrition, we added a consideration of the brainstem as a hunger center and of obesity as a lifestyle problem in developed countries. New information on leptin resistance and obesity and on the role of inflammation in development of atheroscleroisis was added.
• Chapter 33, Nervous Coordination, includes new information on the vomeronasal organ as a pheromonal sense organ in terrestrial vertebrates and the possibility of pheromonal communication in humans. Coverage of taste discrimination was updated, including discovery of a new taste, umami.
• Chapter 34, Chemical Communication, includes new information on steroid hormone membrane receptors, steroid abuse by young people, insulin action in the brain, and the importance of leptin during periods of decreased food intake.
• Within the Immunity chapter (35), we significantly updated the section on innate immunity by addition of material on the exciting discoveries of antimicrobial peptides produced by many invertebrates and vertebrates, responding on first exposure to broad categories of invaders such as gram-positive bacteria, gram-negative bacteria, and fungi.
• Chapter 36, Animal Behavior, covers advances in application of phylogenetic approaches to study of animal behavior, which highlights an important recent advancement in the field. Material was added on the important concepts of reciprocal altruism and evolutionarily stable strategies.

Part Five: Animals and Their Environment

• Chapter 37, The Biosphere and Animal Distribution, features new information on Wallace’s Line and its illustration of the importance of plate tectonics in biogeography. Connections between material in this chapter and that in Chapters 6 and 10 are strengthened.
• In Chapter 38, Animal Ecology, we elaborate the niche concept and have made it more consistent with current leading ecology texts. The discussion of interactions among species in a community (for example, commensalism and mimicry) has been extended.

TEACHING AND LEARNING AIDS

To help students in vocabulary development , key words are boldfaced and derivations of technical and zoological terms are provided, along with generic names of animals where they first appear in the text. In this way students gradually become familiar with the more common roots that comprise many technical terms. An extensive glossary of almost 1,100 terms provides pronunciation, derivation, and definition of each term. Many new terms were added to the glossary or rewritten for this edition.

A distinctive feature of this text is a prologue for each chapter that draws out some theme or fact relating to the subject of the chapter. Some prologues present biological, particularly evolutionary, principles; others (especially those in the survey sections) illuminate distinguishing characteristics of the group treated in the chapter. Each is intended to present an important concept drawn from the chapter in an interesting manner that will facilitate learning by students, as well as engage their interest and pique their curiosity.

Chapter notes , which appear throughout the book, augment the text material and offer interesting sidelights without interrupting the narrative. We prepared many new notes for this edition and revised several existing notes.

To assist students in chapter review, each chapter ends with a concise summary , a list of review questions , and annotated selected references . The review questions enable a student to self-test retention and understanding of the more important chapter material.

The historical appendix , unique to this textbook, lists key discoveries in zoology, and separately describes books and publications that have greatly influenced the development of zoology. Many readers have found this appendix an invaluable reference to be consulted long after their formal training in zoology. The historical appendix will be found on this textbook's Online Learning Center web site at www.mhhe.com/zoology.

Again, William C. Ober and Claire W. Garrison have enhanced the art program for this text with many new full color paintings that replace older art, or that illustrate new material. Bill's artistic skills, knowledge of biology, and experience gained from an earlier career as a practicing physician have enriched this text through eight of its editions. Claire practiced pediatric and obstetric nursing before turning to scientific illustration as a full-time career. Texts illustrated by Bill and Claire have received national recognition and won awards from the Association of Medical Illustrators, American Institute of Graphic Arts, Chicago Book Clinic, Printing Industries of America, and Bookbuilders West. They are also recipients of the Art Directors Award.

SUPPLEMENTS

The Instructor's Testing and Resource CD-ROM provides both an Instructor’s Manual and a Test Bank to support the textbook. The Instructor’s Manual includes annotated chapter outlines, chapter-specific changes for this edition, lecture enrichment suggestions, commentaries and lesson plans, questions for advanced classes, and a listing of resource references for each chapter. The Instructor’s Manual also includes a listing of transparencies and slides available with the book. The comprehensive test bank offers 35-50 objective questions per chapter. These test questions contained in the Instructor's Manual and Test File are also available as a Computerized Test Bank , a test generation system for IBM and Macintosh computers. Using this system, instructors can create tests or quizzes quickly and easily. Questions can be sorted by type or level of difficulty, and instructors also can add their own material to the bank of questions provided. We trust this will be of particular value to first-time users of the text, although experienced teachers may also find much of value.

The Laboratory Manual by Cleveland P. Hickman, Jr. and Lee Kats, Laboratory Studies in Integrated Principles of Zoology , now in its twelfth edition, can be customized conveniently for two semester, one semester, or term courses by judicious selection of exercises.

A set of 150 full color transparency acetates of important textual illustrations are available with this edition of Integrated Principles of Zoology . Labeling is clear, dark, and bold for easy reading.

A set of 148 animal diversity slides , photographed by the authors and Bill Ober on their various excursions, are offered in this unique textbook supplement. Both invertebrates and vertebrates are represented. Descriptions, including specific names of each animal and brief overview of the animal's ecology and/or behavior, accompany the slides.
The Digital Content Manager CD-ROM is a multimedia collection of visual resources that allows instructors to create powerful presentations for the classroom. The Digital Manager CD contains many photos and all of the illustrations from this textbook, along with 200 additional animal diversity images.

An Online Learning Center web site is available with this edition, and contains additional readings, animations, quizzing, key term flashcards, animal diversity PowerPoint slides, and much more. Check it out at www.mhhe.com/zoology.

Although we make every effort to bring to you an error-free text, errors of many kinds inevitably find their way into a textbook of this scope and complexity. We will be grateful to readers who have comments or suggestions concerning content to send their remarks to Fran Schreiber, Developmental Editor, 2460 Kerper Boulevard, Dubuque, IA 52001. Fran may also be contacted by e-mail: fran_schreiber@mcgraw-hill.com, or through this textbook’s web site: www.mhhe.com/zoology.

Cleveland P. Hickman, Jr.

Larry S. Roberts

Allan Larson

Helen I’Anson