Dyreplankton

Dyreplankton, or zooplankton, refers to the animal component of planktonic life in aquatic environments. These drifting or weakly swimming organisms range from microscopic copepods to larger jellyfish, krill, and the larval stages of many marine animals. Zooplankton feed on phytoplankton, microzooplankton, and detritus, while themselves serving as a crucial food source for a wide range of larger organisms. They are found in oceans, seas, and some freshwater systems.

Zooplankton is traditionally divided into holoplankton and meroplankton. Holoplankton spend their entire life cycle as planktonic organisms, with examples including copepods, some amphipods, and krill. Meroplankton are temporary planktonic stages; they include the larvae of fishes, mollusks, echinoderms, and many crustaceans, which later settle to become benthic or nektonic adults. Feeding strategies among zooplankton vary widely, from filter feeding on phytoplankton to raptorial feeding on smaller zooplankton or detritus.

Ecologically, dyreplankton are a vital link in marine food webs. They transfer energy from primary producers to fish, seabirds, and marine mammals, and contribute to nutrient cycling. Many zooplankton species migrate daily between surface and deeper waters, a behavior that also helps transport carbon to the deep ocean through fecal pellets and when zooplankton die.

Distribution and study of zooplankton inform understanding of ocean health and climate change. They are sampled with nets and analyzed through microscopy, genetics, and acoustic methods, providing indicators of ecosystem productivity and responses to environmental change.