Copepoda
Introduction

Marine copepods are small crustaceans usually between 0.2 - 12 mm in length. More than 10,000 species of free-living and parasitic copepods are known to inhabit fresh, brackish, and marine waters and terrestrial localities (Huys and Boxshall, 1991). Marine copepods are known to be pelagic (inhabiting the water column), benthopelagic or hyperbenthic (living in the near-bottom water layers), benthic (living on the bottom or in the sediments) or in association with other animals. Their vertical range is from the surface to abyssal depths and they are known from all the biogeographical zones of the World Ocean in neritic to oceanic waters. Being numerous and abundant marine organisms, they may sometimes form up to 90-97% of the biomass of marine zooplankton, therefore copepods are an important link in marine food webs and the marine economy.

Milne-Edwards (1840) established the Copepoda as a separate taxon. Since that time different classification schemes have been proposed for copepods. Up to now 10 copepod orders are recognized: Platycopioida, Calanoida, Misophrioida, Harpacticoida, Monstrilloida, Mormonilloida, Gelyelloida, Cyclopoida, Siphonostomatoida and Poecilostomatoida. Since 1990 detailed phylogenetic analyses of the Copepoda were carried out by Ho (1990), Dahms (1991) and Huys and Boxshall (1991). The latter authors give an excellent review of existing phylogenies and the history of copepod studies since the eighteenth century up to the early 1990s. The scope of the present work is the known pelagic and benthopelagic fauna of South Atlantic which contains four of the known copepod orders: Calanoida, Cyclopoida, Poecilostomatoida and Harpacticoida. For more detailed information on copepod phylogeny and morphology the reader is referred to Huys and Boxshall (1991), on internal anatomy to Boxshall (1992), and for a bibliography of literature on copepods to Vervoort's publications (1986a, 1986b, 1988).

References for further reading on external morphology, anatomy, phylogeny and definition of the copepod orders, as well as data on feeding and feeding modes, reproduction, development, distribution and taxonomy are given throughout the following text.