Nudibranch & Sea Slug Identification: Indo-Pacific, 2nd edition

Terrence Gosliner, Ángel Valdés, and David Behrens

Three leading scientific experts on nudibranchs and sea slugs, Terrence Gosliner, Ángel Valdés and David Behrens, collaborated to produce a comprehensive guide for divers to the Indo-Pacific region. Originally published in 2014, an expanded 2nd edition was released in 2018. This book illustrates 2,138 Indo-Pacific nudibranchs and sea slugs, including many undescribed species.

The Indo-Pacific represents the largest expanse of tropical ocean in the world, stretching from the Indian Ocean coast of southern Africa and the Red Sea to the central Pacific of the Hawaiian Islands, Easter Island and the Marquesas. This region supports the most diverse marine fauna of any place in the world for most groups of organisms. The opisthobranchs (nudibranchs and other sea slugs) are no exception to this rule. There are about 3,000 described species of opisthobranchs in the world and at least 40% of these have been found exclusively in the Indo-Pacific tropics.

With the evolution of chemical defenses and the loss of the shell, came the evolution of the bright color patterns that are the signature of nudibranch diversity; vivid colors advertise the presence of toxicity or distastefulness. Other species went down the track of being cryptic, blending in with their surroundings and some evolved amazing strategies of resembling their specific prey.