THE BIOLOGY OF FROG AND TOAD TADPOLES

Abstract

McDiarmid, R.W. & Altig, R. ( eds ) ( 1999 ) Tadpoles: the biology of anuran larvae . University of Chicago Press, Chicago . xiv + 444 pp, figs, tables, index . Hardback: Price £49.00, US$70.00 . ISBN 0 226 55762 6 . The introduction to Tadpoles starts with a quote from a commencement address given by Kermit the Frog: ‘When I was a tadpole growing up in the swamps, I never imagined that I would one day address such an outstanding group of scholars’. This quote, and the rather dated cover picture, sets the relaxed and chatty editorial tone for a significant review volume with chapters by 14 authors. Unfortunately the book starts on a very mundane level with a chapter by the editors on techniques. Do we really need to be told: ‘A good microscope with variable magnification and strong, preferably fiber-optic lights, also of variable intensity, are prime requisites’? This material would have been better at the end in an appendix. They then deal with the basic body plan and in the last chapter provide a valuable guide to larval morphology where the limitations of present knowledge are also discussed. Cannatella has written the first of three chapters with an anatomical slant. It is a clear and well illustrated account of the cranial and axial musculoskeleton. Viertel and Richter then describe the viscera and endocrines in a readable account with some beautiful diagrams and micrographs. As a tadpole neurobiologist I wished that Lannoo’s chapter on nervous and sensory systems had been fuller. This is a very active area where Xenopus is used extensively as a model system in both developmental and functional studies on the nervous system. However, information on cellular neuroanatomy is not mentioned. This is specialized information, but the fact that many tadpoles are like jellyfish, having excitable skin and a propagated ‘skin impulse’ which tells them about stronger noxious stimuli, would surely be of general interest. An essay on endotrophic anurans by Thibaudeau and Altig leads on to a very useful review of physiology, followed by chapters on behaviour and ecology. There are areas of clear overlap in the material on behaviour and ecology. For example, cannibalism is dealt with first under behaviour, and I was rather disappointed until I looked in the index, which led me to the later ecology chapter. What was surprising was the lack of cross-referencing. As one might expect, there are fascinating examples of curious behaviour, such as that of the Central American frog Dendrobates pumilo. Here the mother returns once a week to feed individual tadpoles she has placed in bromeliad leaf axils by laying an egg after the tadpole has performed a special tail-vibrating ‘dance’. The behaviour chapter is frustrating at times because work is cited but the results are not given. I liked Alford’s review of ecology even though it gave only a brief mention to one of my favourite stories. Caldwell observed that tadpoles of Acris are cryptically coloured in permanent ponds with fish predators, but have a prominent black spot on the end of the tail in temporary ponds where dragonfly nymphs are the dominant predator. She suggested that the black spot was selected for in temporary ponds as the nymphs will then strike at the end of the tail increasing the chances for escape by the tadpole. The last chapter before the review on diversity is by Harris and is on evolution. A diverse book about a diverse group will probably not satisfy anyone, but for all of us who are interested in tadpoles this is a valuable reference work, which I hope I can persuade my library to buy. I found the editorial style unselfcritical and long-winded, but some of the chapters in this book will be really useful, including the last synthetic chapter on diversity. This is a good book to consult and dip into to uncover new references and interesting stories.