Entomology for the copepodologist

Abstract

Copepods are often called 'insects of the seas'. Is this justified? Today insects are regarded as the most successful group of animals. Measures of absolute success are phylogenetic age (survival through time), dominance (relative abundance, proportion of total biomass, role in energy flow, impact on ecosystems and coexisting organisms), speciosity, geographic range, and breadth of adaptive radiation. Measured by these criteria copepods are no less successful than insects. What about relative success? There must be intrinsic features in the structure and mode of life of insects which make them more successful relative to other animal groups. According to the literature these features are small size, metamorphosis, wings, and mouthparts. If the capacity to fly is equated with the capacity to swim copepods share all these intrinsic features being equal with insects also in relative success. Entomologists believe insects to be unmatched by other groups in most features of evolutionary success. Yet, they outdo copepods only in one respect: number of species. Reasons for this are greater spatial heterogeneity and architectural complexity (of vegetation) on land than in the sea as well as the fact that insects were among the first groups on land relatively unaffected by other groups, whereas copepods had to evolve in an already crowded world. © The Author 2006.