The haptophyte algae (sometimes referred to as the prymnesiophyte algae) are cosmopolitan in their distribution and are particularly important in marine ecosystems. They form a significant component of the phytoplankon and may occasionally be the dominant organisms.In recent years there has been a marked increase in these algae, partly as a result of the occurence of a number of ichthyotoxic blooms in Scandinavian coastal waters, whose effects have been dramatic in terms of both the diversity of species affected and their economic impact. It is also now recognised that some members of the Haptophyta may affect our climate through the production of volatile sulphur compounds and through the effects that calcifying biomineralization may have on ocean/atmospheric carbon dioxide exchange.This is the first monograph on the Haptophyta, each chapter having been contributed by authors experienced in their subject. The topics covered include all major aspects of haptophyte biology, such as their structure, biochemistry, ecology, climatological and economic importance, fossil record, evolution and systematics.