01958nas a2200193   4500008004100000022001400041245003700055210003600092260001900128300001300147490000700160520143100167100001701598700002101615700001601636700001801652700002001670856007401690       2011                        eng d  a0065-288100aBiology of Deep-Water Octocorals0 aBiology of DeepWater Octocorals  bAcademic Press  a41 - 1220 v603 aPublisher Summary This chapter discusses the taxonomy, phylogeny, biogeography, ecology, and reproductive biology of deep-sea octocorals and also focuses on gorgonian octocorals because they are the predominant octocoral group in the deep sea. The most widely accepted taxonomic scheme for octocorals divides the subclass into four orders: (1) helioporacea, (2) alcyonacea, (3) gorgonacea, and (4) pennatulacea. The distinctions between most orders and suborders are blurred by intermediate taxa that resulted in a continuum of colonial organization and skeletal structure. The major areas of study of deep-sea gorgonians and sources of species descriptions are also summarized. Octocorals have been known from deep water in the North Atlantic, although the Challenger expedition showed that octocorals could be found in the depths of all oceans. Knowledge of deep-water octocorals of the Indo-West Pacific region is meagre and contrasts with the wealth of information on shallow-water taxa. The distribution of the three major deep-sea families’ discussed are––chrysogorgiidae, isididae, and primnoidae. Deep-sea octocoral colonies are often large so it offers a wide range of biogenic habitats to other invertebrate species. The chapter also focuses on those invertebrate species that are found most frequently on the octocoral host. Reproduction, growth, age, food habits, and conservation issues are also considered.1 aWatling, Les1 aFrance, Scott, C1 aPante, Eric1 aSimpson, Anne1 aLesser, Michael  uhttp://www.sciencedirect.com/science/article/pii/B9780123855299000020