The Biology of Sea Turtles, Volume II

Edited by:
  • P. L. Lutz,
  • J. A. Musick &
  • J. Wyneken
CRC Press: 2002. 455 pp. $99.95
Turning turtle? The risk of extinction may have been exaggerated for some turtle species. Credit: N. MROSOVSKY

Watching a large turtle emerge from the sea at night to lay its glistening white eggs in the sand is an unforgettable and powerful experience. Sadly, some turtle populations are in serious decline, although others are increasing, leading to debate about whether the risk of extinction has been exaggerated. But biologists and conservationists can all seem to agree on the value of having a better understanding of sea-turtle biology. In the past decade, studies using mitochondrial DNA, satellite tracking and temperature-determined sex ratios have proliferated, as have low-tech beach surveys.

However, too often researchers lack integrative reviews and easy access to carefully archived results. Unrefereed extended abstracts from conferences are often quoted, for want of other sources. The Marine Turtle Newsletter has higher standards and sometimes contains important items, but it focuses on alerting readers to developments in their initial stages. So, when the first volume of The Biology of Sea Turtles appeared in 1997, it enjoyed considerable success and was frequently cited.

This is now followed by a second volume, which has an emphasis on reproduction (gonadal development, breeding cycles and sex determination). It also covers a variety of other topics, from husbandry to sensory abilities, and includes thoughtful discussions of growth, age at maturity and population trends. A quarter of the contributions to the volume concern not so much biological as historical, cultural, economic and conservation-oriented aspects of the subject.

Although these reviews are likely to be highly cited, most tend to inform rather than illuminate. For example, a useful chapter on anatomy mentions the highly vascular cartilage of the leatherback turtle. The exciting thing about this work, not captured by a mere reference to the original description, was the creative extrapolation from anatomy to physiology, implying some degree of endothermy in the leatherback. Critical evaluation and guidance about which studies are methodologically best, and why, are often lacking. To fulfil their potential, reviews should be more than the sum of their parts.

Editing seems to have been minimal, resulting in some overlap in text and illustrations. Some photographs are reproduced in both colour and black-and-white, several chapters include similar photographs of gonadal structure, and one photograph, which shows the stages of spermatogenesis, appears twice. It has been said that a picture is worth a thousand words. For pictures illustrating the same thing, 500 each at best would be allowable — make that 250 for photographs lacking scales or resolution.

In contrast, the chapter on migrations and satellite tracking would have been enhanced by including some figures. The editors have not attempted any integration, cross-referencing or explanation of discrepancies. For example, one of the better, more synthetic chapters compares life histories with a mitochondrial-DNA phylogeny for the “seven extant species” of sea turtle, but other chapters assume that east Pacific green turtles are a separate species, and so end up with eight.

But despite these problems, The Biology of Sea Turtles is one of the best places to start — though not to stop — and both volumes may be recommended to libraries and individuals.