Invertebrates. 2nd ed. Richard C. Brusca and Gary J. Brusca. Sinauer Associates, Sunderland, MA, 2003. 936 pp., illus. $109.95 cloth (ISBN 0878930973).
Richard C. Brusca (director of conservation and research at the Arizona–Sonora Desert Museum and widely recognized invertebrate zoologist and isopod crustacean specialist) and Gary J. Brusca (professor at Humboldt State University from 1967 to 1998 and amphipod crustacean specialist) have published a substantial update to their 1990 Invertebrates text. Like its predecessor, this book is intended to support the lecture component of a one- or two-semester upper-division college course in invertebrate zoology. It is dedicated by Richard to his late brother Gary, who died in 2000. This book clearly reflects the two brothers' extraordinary collective efforts to update their already comprehensive coverage of invertebrate animals and Protista.
The striking image of a swimming medusa (Pelagia) on the new cover was my first clue to the pleasant surprise I got when I started exploring all the beautiful and informative illustrations, including many in full color, a contrast to the strictly black and buff illustrations in the former edition. These new illustrations are bound to please both instructors and students. An excerpt from the substantially revised chapter on Protista has been made available for downloading by the publisher in PDF format ( www.sinauer.com/brusca). I recommend that those familiar with the first edition download this chapter to see just how spectacular the illustrations are throughout this new edition. Another change is that the illustration sources and credits have now been moved to the rear, more directly conveying pertinent information to students yet also somewhat diminishing the appreciation of ongoing research for a student pondering a classic account of natural history.
This new edition is 14 pages longer than the 1990 edition but slightly less massive because of its thinner, shiny white paper stock and slightly smaller font size. My side-by-side comparisons of old and new editions revealed that some outdated paragraphs or sections had been appropriately dropped, while other snippets of text reflecting updates had been inserted. Many problems with the first edition have been corrected. The references at the end of each chapter are somewhat updated, preserving most of the older citations. Like the former edition, this is hardly a text an instructor can expect students to read from cover to cover. Two recent invertebrate zoology texts (one by Janet Moore, An Introduction to the Invertebrates, and one edited by D. T. Anderson, Invertebrate Zoology; see http://biology.fullerton.edu/biol461/texts.html) are shorter and more affordable for students. On the other hand, I have found that most students prefer having a more encyclopedic reference when questions arise in the laboratory.
The approach taken in this edition of Invertebrates is very similar to that of the 1990 edition. The Bruscas have once again emphasized functional morphology and phylogeny as organizing principles. The introductory four chapters remain one of the best available overviews of the unifying principles of comparative zoology. These chapters are concise and general enough that they can serve as required reading assignments early in the semester, presenting the students with an excellent overview of, especially, functional morphology and development.
The overview of classification, systematics, and phylogeny (chapter 2) is somewhat less successful and is dense in places. One addition is a section entitled “The Bauplan and Related Concepts” (box 3A, p. 42). The Bruscas relate the notion of bauplan (from a German term meaning more precisely “blueprint” than “ground plan”) directly to Richard Owen's 1848 essentialist concept of archetype, but they attempt to place it in a more evolutionary perspective. The expanded treatment is welcome, given how much this concept is featured in both editions. This is also one of the few places where new concepts and advances in “evo-devo” (the emerging field emphasizing comparative evolution and development from a molecular perspective) are discussed. Following Stephen Jay Gould and others, the Bruscas view the bauplan as related to developmental canalization, the notion that populations of organisms are constrained in how they might evolve by the conserved nature of their genetic tool kit controlling pattern formation. The connection between old hypotheses about bauplan and new understanding of pattern formation is interesting and relevant, but bauplan notions still reek of essentialism to me. Why not just point out that there are some very conservative characters in nearly every animal group? Bauplan reconstruction is also notoriously dependent on phylogenetic estimates, and there are generally more current alternatives than the phylogenetic views presented in this text (see the discussion of phylogenetic analyses of metazoans below). Even if the phylogeny were certain, there are invariably ambiguities associated with estimating ancestral character states for any particular taxon.
The first edition was one of an unlikely spate of excellent and generally encyclopedic invertebrate zoology texts published in the early 1990s, with other notable texts by Ruppert and Barnes, Pearse and Buchsbaum, Kozloff, Pechenik, and Meglitsch and Schram. Enrollments in invertebrate zoology courses were dwindling nationwide, and some of us wondered how the seemingly limited market could sustain this wealth of marvelous new texts. Then came the still ongoing molecular systematics boom, evo-devo became a vibrant emerging field, and bizarre animals from the Burgess Shale made it to the cover of Time magazine. In this decade, invertebrate zoology instructors are struggling to present newly emerging cross-disciplinary views and approaches, many involving phylogenetic considerations, yet current textbooks are all outdated. While most courses seem to be retaining a group-by-group style of presentation, there is now a tremendous opportunity to capture the excitement of emerging phylogeny-based comparative approaches within invertebrate zoology courses.
Despite its emphasis on phylogeny, Brusca and Brusca's new edition harkens back to 1990 not only in its dated phylogenetic hypothesis but also in its omission of many recent landmark studies, especially those from a molecular perspective. I found its updates in this area uneven, often reflecting the authors' skepticism toward newer results. Not surprisingly, given the crustacean expertise of the Bruscas, the arthropod chapters appear to be the most thoroughly revised, and the authors even suggest there is now molecular evidence supporting a clade of hexapods and crustaceans. As in the first edition, major groups such as Mollusca have not received as much attention. Recent alternative proposals of higher-level animal relationships, such as the growing evidence for the monophyly of Lophotrochozoa and Ecdysozoa groupings; sister taxon relationships within Deuterostomia (e.g., Echinodermata and Hemichordata); the proposed basal position of acoelomorph flatworms with Bilateria, apart from other flatworms; and the potential paraphyly of sponges are all examples of widely accepted new views that are almost completely ignored. The chapter on Protista unfortunately has no broad phylogenetic overview of where the covered taxa are found within eukaryotes. The evidence that choanoflagellates are the likely sister taxon of multicellular animals is obscure, at best, and there is no mention that metazoans and choanoflagellates are now considered part of Opisthokonta—a clade that also includes the recently characterized meso-mycetozoeans (unicellular parasites of various fish, birds, mammals, and snails, also known as ichthyosporeans) and fungi, neither of which are mentioned.
The eclectic presentation of phylogenetic analysis and classification in the first edition is only slightly updated. The advertisements for this edition claim this text now incorporates “new developments in phylogenetics, developmental biology, and molecular genetics,” but the Bruscas' text is more useful as a reference source than as a current overview of animal phylogeny.
This edition at least does have a character matrix (appendix B) in support of the authors' summary cladogram of animal relationships. Unfortunately, the matrix appears to be mostly a compilation of the authors' previously featured node-by-node listings of diagnostic features rather than a less tree-dependent attempt to score morphological variation. There is suspiciously little homoplasy indicated across any of the trees, and the authors still often assert an assumed polarity of character evolution or argue that particular characters are convergent when they conflict with their favored hypothesis. Thus, it is not surprising that Brusca and Brusca's new summary tree is effectively the same in topology as the corresponding one in the first edition, one that is at odds with many aspects of other current phylogenetic estimates of metazoans based on either morphology or molecules or a combination of these data types. Still, as a teaching device, the presence of a matrix and added explanation of the methods used to generate the tree figure is clearly a step in the right direction.
Despite the quirks I have noted, the book has worthwhile views to offer that are lacking in most competing texts.
