copepodi

Copepodi, or copepods, are a group of small crustaceans that form a dominant part of aquatic zooplankton. The term copepodi is used in some languages as the plural form of copepod. They occur in nearly all aquatic environments, from the open ocean to freshwater bodies, and from polar to tropical regions. Most species are free-living, but a substantial minority are parasitic on fish, invertebrates, or marine mammals. Copepods range in size from under a millimeter to a few millimeters.

Morphology and life cycle: Typical copepods have a compact body with a distinct anterior prosome and a slender abdomen, and they possess paired antennae, often with the first pair being long and used for swimming and sensing. They undergo direct development through nauplius stages (I–IV) followed by copepodite stages (I–V) before reaching adulthood. Reproduction is usually sexual; females often carry eggs in sacs attached to their body or brood them until hatching.

Ecology and feeding: Feeding modes vary from filter feeding and detritivory to herbivory and omnivory; several species are also predatory. A well-known subgroup comprises parasitic copepods that attach to fish gills, skin, or fins, which can impact aquaculture and wild fish populations. In general, copepods are a major food source for many planktivores, including small fish, invertebrates, and marine mammals, making them a crucial link in aquatic food webs.

Importance and applications: Copepods are essential for nutrient transfer in aquatic ecosystems and are widely used as live feed in aquaculture. They also serve as model organisms in ecotoxicology and climate-related studies due to their sensitivity to environmental conditions.