Reviewing a science book for high-school honors courses

Marine Life and the Sea
1995. 495 pages. ISBN: 0-534-16314-9. Wadsworth Publishing Co.,
10 Davis Drive, Belmont, California 94002. (Wadsworth is a part
of International Thomson Publishing Inc.)

A Superb, Exciting Textbook
That Pursues a Sublime Goal

Gary C. Williams

[Editor's note: The other marine-biology texts that Gary C. Williams has appraised in TTL are Mosby's Marine Biology (see our issue for March-April 1992) and Wm. C. Brown's An Introduction to the Biology of Marine Life (see the issue for September-October 1992).]

In his preface Milne announces two objectives, the first of which is to enable readers to understand the probable responses of the oceans and marine organisms to human activities. The second is "to convey an appreciation for the intrinsic beauty and value of marine plants and animals, apart from their roles as unpaid crew members who maintain humanity's life-support machinery in the hold of spaceship Earth." This is a sublime goal, and it helps to imbue Marine Life and the Sea with a refreshing tone of originality.

The body of the book has five parts, each containing two to seven chapters. Part I, "The Global Oceans," is an introduction to oceanography. Part II, "Living in Seawater," begins Milne's consideration of the adaptations displayed by creatures that inhabit the seas. Part III, "The Marine Organisms," is a taxonomic survey -- one chapter about marine microbes, plants and fungi, one chapter about invertebrates, and two about vertebrates. Part IV, "Marine Ecology," is the longest; Milne introduces basic concepts (such as the population, the community and the ecosystem), describes how energy and materials move through ecosystems, and concludes by examining some reasons why marine communities may undergo long-term changes. Part V, "The Human Impact on the Sea," concentrates on how we are polluting marine environments, how we are depleting or destroying fisheries, and how human-induced changes in the atmosphere can alter physical and biological processes in the oceans.

Milne's writing is fluent and readable, his illustrations are generally lucid, pertinent to the text, and appropriately placed, and he has employed several devices that make his chapters inviting. Each chapter starts with an interesting vignette, followed by a box that states the chapter's theme. Then, within the chapter itself, topics are introduced by blue headings which often are surprisingly informative and which tempt the student to read on. Some examples: Warm ancient waters, modern ice. . . . Oxygen is scarce in the oceans . . . Gills make fishes vulnerable to loss of heat and loss of water . . . The lights of some predators attract or spotlight prey . . . Giant living hot-oil balloon? . . . Dinoflagellates are distinguished by cellulose, flagella, and diversity . . . Crinoids and sea daisies are deep-sea surprises . . . Salmons are commercially small-scale, politically colossal . . . Vertical migration of mesopelagic animals is puzzling . . . Was the great eelgrass epidemic of 1931 a preview of an effect of global warming?

The chapter-opening vignettes present material of current or historical interest, and some provide factual information that I haven't found in other marine-biology texts. At the start of chapter 1, for example, a piece titled "The Ocean at 12 O'Clock High" suggests that the largest ocean in the solar system may not be on Earth but may be on Jupiter's moon Europa; the entire surface of Europa appears to be covered by a crust of ice, ten kilometers thick. Chapter 2 begins with an article about UFOs, meaning "unidentified floating objects"; the article focuses on the huge nuts known as cocos de mer. Chapter 6 opens with "The Emperor of Japan -- Marine Biologist," in which Milne tells about research conducted by Emperor Hirohito (1901-1989) at Sagami Bay. Chapter 7 offers "Sherlock Holmes and the Most Dangerous Marine Animal," telling how Arthur Conan Doyle built one of his Holmes stories around the jellyfish Cyanea capillata.

Other than the chapter-openers, there are few feature articles or sidebars in Marine Life and the Sea. This is a pleasing difference between Milne's book and some others, whose pages are cluttered with sidebars that interfere with the flow of the text and distract the reader. The handful of sidebars that Milne has included are valuable. Examples include "The Sizes of Things" (on page 134) and "What the Heck Is a Plant, Anyway?" (page 86). In the latter piece, Milne discusses names that are applied to photosynthetic organisms. He states that "The vernacular terms used to refer to these groups are wildly ambivalent," and he proceeds to explain the multiple meanings (some broad, some strict) of terms such as algae and plants.

• Page 128: The five-kingdom classification of life, which Milne uses here, should no longer be presented in biology texts. Though it is familiar and convenient, it is also defective and misleading because the "kingdom Protista" is a hodgepodge of separate lineages. This "kingdom" does not consist exclusively of a single ancestor and all of the ancestor's descendants; it does not meet the criterion of monophyly, and it therefore is not a natural group. Instead of dignifying such artificial categories and perpetuating the five-kingdoms fancy, prudent textbook-writers should emphasize the three great, monophyletic groups of living things: the archaebacteria, the eubacteria, and the eukaryotes.

• On page 153 Milne introduces the term "invertebrates," which he uses frequently in the rest of the book. It is high time for this term to be expunged from our lexicon of formal names and from all discussions of classification. The so-called invertebrates constitute an artificial group whose only shared feature is that they don't have something -- a backbone. Lumping cnidarians, mollusks, annelids and crustaceans as "invertebrates" is rather like lumping bananas, grapes, apples and plums as "unoranges" because they don't have orange rinds. A textbook should simply refer to the cnidarians, the mollusks, and all the other phyla by their individual names.

• Page 155: Figure 7.1, "Evolutionary relationships of the living animal phyla," is hopelessly confusing and extremely misleading, bordering on ridiculous. It shows no fewer than thirteen separate origins of animals from protistan ancestors! Does Milne really believe that the animals constitute a heterogeneous assemblage of thirteen unrelated lineages? To make matters even worse, the symbols are botched: The legend says that open dots denote the forerunners of modern phyla, but the forerunners seem to be represented by solid dots on the diagram. A simple cladogram of the animal lineages covered in the book's text would have shown that the animals are monophyletic and would have summarized our present knowledge of animal phylogeny.

Minor cases of confusion include figure 1.6, in which a single symbol (a dotted blue line) seems to denote three different things on two separate maps. And this book, like so many others, arouses a complaint about the way in which it covers marine animals: As I noted above, Milne has devoted two chapters to vertebrates (which represent only one part of one phylum), but he has given only a single chapter to all the rest of the animals put together.

In the chapter about our extraction of marine organisms, Milne alerts us to one of the hazards that we have created for ourselves:

The marine harvest makes up only 2% of the food produced by human endeavors each year. However, it contributes about 12% of the protein supply. The importance of this fact can hardly be overstated. As agronomist Georg Borgstrom pointed out in 1964, it is easy to supply the entire human population with enough calories (for example, by planting all U.S. cropland with sugar beets), but it is far more difficult to supply everyone with sufficient protein. . . .

The prospect that the marine harvest may be approaching its limit (or may overshoot the limit and decline) suggests that the oceans' contribution to human nutrition may falter . . . . At best, the oceans probably cannot provide more food for humanity [than they are providing now] on a sustained basis.

In the chapter on "Changing the Oceans by Changing the Atmosphere," the topics include the effects of global warming on the oceans, the depletion of stratospheric ozone, the controversial Gaia hypothesis, and the recent idea that oceanic dimethylsulfide (produced by phytoplankton and seaweeds) may create a climate-cooling effect that would counteract global warming. Knowing about these topics is especially important at a time when mass-media demagogues (such as the proprietors of radio "talk shows") are urging their followers to believe that global warming and ozone depletion are just fantasies invented by neurotic environmentalists. In truth, global warming and ozone depletion are both real and dangerous, as anyone knows who has been paying close attention to the contemporary scientific literature -- especially reports in the journals Science and Nature.

Milne concludes Marine Life and the Sea with "The Author's Last Word." Here he draws attention to the explosive, destructive growth in human numbers:

[We] are long past the point at which efforts to accommodate human population growth are beneficial or even harmless. Exploding human numbers are ripping the fabric of the oceans and the planet asunder. . . . Proposals for endlessly increasing the harvest from the seas or using the oceans as a sinkhole for wastes are simply last-gasp efforts to perpetuate the illusion of limitless growth. . . . A century hence, after the oceans' potential to absorb waste has been fully exploited, after their populations of fishes and whales and shellfish have been devastated in a race to keep up with human numbers, then what? . . . . For the sake of humanity, for the health of the oceans and the planet, for the sake of Earth's ability to sustain the next thousand generations in wealth, health, beauty, and inspiration -- human population growth must stop. There is no other way. This is our greatest challenge.

That is a lesson that all of us -- not just high-school students or college students -- must understand.

David Milne Has Written
a Good Textbook, but . . .

Leighton Taylor

At this point you can sense that I do not regard Marine Life and the Sea as a complete success, and you suspect that I am working my way toward a "but" or a "however" that will introduce some objections to Milne's book. That is right. As the philosopher Pee Wee Herman has said, "Everyone has a big but." Still, I want to describe some of the laudable features of Marine Life and the Sea before I tell about my reservations.

Milne is an accomplished teacher, and he says (in his preface) that his book reflects his pedagogic experiences and his interest in helping others to teach his subject:

The mechanics, layout, emphasis on illustrations, examples, and language of this text are partly the result of the author's observations as a teacher. Readers best learn subjects that are clearly explained, illustrated in pictures, presented from several different perspectives, and applied to new situations. (The subject should also be inherently interesting; with marine biology, that is guaranteed from the start.) . . .

Although this book is primarily intended for people who want to become familiar with the sea, it is also written for my fellow marine biology teachers. Like them, I have often come across interesting puzzles that I couldn't figure out or hints of interesting phenomena that I didn't have time to research. . . . I've made a special effort to run down many such mysteries and include them for the benefit of colleagues who, like most teachers, seldom have time to research the topics themselves.

Milne is the only person whose name is shown on the title page of Marine Life and the Sea, but he acknowledges his authorial debt to various colleagues and also to persons who stimulated his early interest in living things:

A kid next door (name now forgotten) who never failed to find the insects pictured in his amazing book, authors (Robert Hegner, Raymond Ditmars, Roy Chapman Andrews) who sparked and sustained a young boy's imagination, and a remarkable high school biology teacher (Robert Rogers) would all recognize something from their experience in this text.

Let me digress to note that, while he cannot recall his playmate's name, Milne remembers the name of his biology teacher. I hope that today's science teachers will find this heartening and will look forward to the day, thirty or forty years from now, when grateful scientists will remember them and will thank them by name for their efforts.

For me, the most pleasing aspect of the book is its emphasis on the fact that humans are now the dominant organisms in almost every ecosystem, with influence over the entire living world. This point becomes the theme of Part V, a reasoned and balanced review that consists of three rich chapters. Chapter 17, "Additions of Materials to the Oceans," examines the effects of oil spills and of our using the oceans as sinks for sewage and industrial wastes. Chapter 18, "Changing the Oceans by Harvesting Organisms," tells about some major problems associated with fisheries and our destruction of fish stocks. It includes an account of a classic case -- the collapse of the Peruvian anchoveta fishery -- and it has a good section on "Effects of Fishing on Non-Target Species"; in this section, Milne explains how heavy exploitation of walleye pollock in the North Pacific has affected populations of other species, from kittiwakes and auklets to Steller's sea lion. Chapter 19, "Changing the Oceans by Changing the Atmosphere," focuses on the effects of global warming and ozone depletion on marine environments and marine organisms.

Best of all, Milne does not shrink from stating that all of our destructive impacts on marine systems are "hyperactively driven by relentless explosive growth of the human population," and that this growth must be stopped. Here is his plea, presented in an afterword entitled "Saving the Oceans -- and Humanity":

[We] are long past the point at which efforts to accommodate human population growth are beneficial or even harmless. . . . For the sake of humanity, for the health of the oceans and the planet, for the sake of Earth's ability to sustain the next thousand generations in wealth, health, beauty, and inspiration -- human population growth must stop. There is no other way. This is our greatest challenge.

Like many a teacher, Milne is eager to devise generalizations and to convey them in memorable and even dramatic ways, and this sometimes leads him to be a bit sloppy with his facts and his logic. In reading his chapters about the subjects with which I am especially familiar, I have found enough mistakes, misinterpretations and omissions to cause me some concern -- and this makes me worry about how reliable Milne has been in his discussions of subjects that I know less about. I am worried about whether his occasional carelessness in the presentation of facts and arguments will mar his credibility and keep him from gaining his readers' trust. And I am worried about whether some of his flawed arguments may be useful to ideologues who deny that the oceans are being degraded by human influences, deny that exploding human populations are jeopardizing all living systems, and deny that we have to take action to keep Earth livable. Here are some of the things that have given me pause:

• On page 188 a diagram purports to display the number of species in each major group of vertebrates, but the numbers pertaining to fishes seem radically low: 12,000 species in the oceans, 6,800 in fresh water. Reputable estimates based on checklists and faunal surveys put the number of fish species at 25,000 to 30,000.

• An illustration on page 232 shows a sea otter and a chart of "an otter's typical daily catch -- what it eats in a day." The "typical daily catch" is depicted as a combination of sea urchins, abalones, rock crabs, kelp crabs and turban snails, but this is misleading. The sea otter, as a species, may eat all of those things, but individual otters specialize in eating only one or two of them, and the "typical daily catch" varies from individual to individual and from place to place. The management of sea otters and their prey is already contentious because some of the prey species are valued by humans and are sought by commercial fishermen. Milne's illustration confuses and obscures important points, probably because he has summarized some information out of context.

• Pages 189 through 193: The material about sharks and the other elasmobranchs has not been prepared carefully. Space that could have been used for a serious discussion of shark biology has been given to dubious cartoons, to an anecdote from Thor Heyerdahl's story of his voyage on the raft Kon Tiki, and to some of David Baldridge's less-than-rigorous analyses of shark attacks on humans. Whale sharks are labeled as "rare," an unexplained description that strikes me as questionable. There are two paragraphs about elasmobranchs that feed on plankton, but neither paragraph mentions the famous "megamouth," Megachasma pelagios -- the big plankton-eating shark that was discovered in 1976. In the figure that supposedly shows some representative elasmobranchs, the illustrator has confused a saw shark with a sawfish, which is quite a different animal. And though Milne eventually remarks (on page 206) that there are "major differences in physiology and embryology" between elasmobranchs and "true fishes," his text fails to provide any comparative physiological or embryological information.

• Page 203: A headline says "Salmons are commercially small-scale, politically colossal," but Milne fails to substantiate this. In his thin text he mentions unspecified "treaties" with nameless American Indian tribes, and he vaguely alludes to "conflict" and "political turmoil" involving sport fishermen, commercial fishermen and aquaculturists. But what are the conflict and the turmoil about? He doesn't say. I'll bet that readers would like to know about how salmon stocks are affected by disease, by overfishing, and by the genetic swamping of wild populations by hatchery-raised fish. And what about the effects of dams, water-diversion projects, and logging? These are some of the sources of the "conflict" and "political turmoil" that surround salmon fisheries, and Milne should have provided some explanation of them.

• Pages 226 and 227: I do wish that Milne's discussion of the Endangered Species Act were more cogent. It would be a lot better if Milne had emphasized and explained that the degradation and destruction of habitats are the principal reasons why many species have become endangered (and why many populations have actually been driven to extinction). Understanding this is especially important today, because current right-wing efforts to weaken the Endangered Species Act are focused on abolishing or subverting the Act's power to protect habitats on so-called private lands. (See the article by John H. Cushman, Jr., in the 30 June issue of the New York Times. See also the editorial "Protecting Endangered Species" in the same issue.)

Maybe I'm picking nits, and maybe I'm asking too much of a book that, overall, does a good job. But when the stakes are so high, and when an author adopts the admirable pedagogic goals that Milne has described in his preface, I can't help feeling some disappointment. Marine Life and the Sea is a good book, but Milne can make it even better in its next edition.

Gary C. Williams is a marine biologist and a department chairman at the California Academy of Sciences, in San Francisco. His research program includes the systematics and biogeography of marine coelenterates and mollusks, as well as aspects of coral-reef biology. His current field work is focused on coral reefs of the western Pacific.

Leighton Taylor, a marine biologist, operates Leighton Taylor & Associates (in St. Helena, California), a company that offers planning and design services to science museums and to other institutions that present science to the public. He also writes extensively about marine subjects. His book Sharks of Hawaii: Their Biology and Cultural Significance was published in 1993 by the University of Hawaii Press.

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