It has long been recognized that biological activity has a large influence on biogeochemical cycles in the ocean. However, the recognition that the ecosystem composition may also be significant is more recent. The newest generation of biogeochemical models used to study climate-ocean interactions represents the diversity of planktonic ecosystems by grouping similar species into “plankton functional types” (PFTs). These models can thus include specific biogeochemical processes mediated by distinct PFTs, such as the ballasting effect of mineral shells, the aggregation effect of some organic material, and the packaging effect of grazing by large zooplankton