Pelagic Snails. The biology of holoplanktonic gastropod mollusks
Carol M. Lalli & Ronald W. Gilmer

Published 1989
Stanford University Press: Stanford, California.
ISBN 0804714908 cloth
276 pp.
Price approx: $US 77.95

Until this book was published 20 years ago, our knowledge of the biology and ecology of pelagic snails had not really advanced from the guesses of the 19th century naturalists who were aboard the earlier oceanographic voyages, or who studied the preserved specimens brought back by such expeditions. Even as technology advanced in the 20th century, all that happened was that expeditions became more efficient at collecting and preserving greater quantities of dead specimens.

In this book Carol Lalli and Ronald Gilmour give us the first comprehensive glimpse at an amazing world of animals which have evolved adaptations far beyond the imagination of those who had studied just the dead specimens. For example, who would have thought that shelled pteropods like Limacina would feed by entangling plankton in a huge mucus net many times their body size - quite different from the orthodox view that they filtered particles in their mantle cavity. Some of these snails can produce spectacular feeding webs two meters in diameter.

The molluscs have produced many swimming and oceanic forms, the most notable being of course the squid, and amongst the gastropod snails, which are the topic of this book, pelagic forms have evolved many times. In this book there are chapters on the raft building janthinid snails, the heteropods, the opisthobranch pteropods [Thecosomata, Gymnosomata] and the nudibranchs such as Glaucus and Fiona. Each chapter presents new information on almost every aspect of their biology and natural history and includes an extensive bibliography of published research.

Most of these animals are difficult to find, and even more difficult to study alive in their natural environment. This book is the result of many years study and is the first biological treatment of the approximately 140 known species of pelagic snails. It concentrates on the biology and natural history of the animals and is illustrated by a fascinating collection of colour, black & white photos, and sketches. It has always been one of the most valued book in my collection.

Why then have I not mentioned this book before? Simply because I had been told by a bookseller that it was out of print. Happily Carol Lalli let me know that copies are still available from Stanford University Press at I would certainly encourage anyone with more than a passing interest in sea slugs, to seriously consider adding Pelagic Snails to their library.

Bill Rudman

Authorship details
Rudman, W.B., 2007 (August 9) Pelagic Snails. The biology of holoplanktonic gastropod mollusks. Carol M. Lalli & Ronald W. Gilmer. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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