copepodids

Copepodids are the larval stages of copepods, a diverse group of small crustaceans in the subclass Copepoda. After the nauplius stages, copepods enter a series of molts collectively known as the copepodid stages. In most species these stages are designated C1 through C6, with each molt producing a larger, more mature juvenile. The copepodid stages are generally the first post-naupliar life forms capable of feeding and, in many free-living copepods, occupy a key position in aquatic food webs as consumers of microalgae and as a source of nutrition for larger zooplankton.

In free-living copepods, copepodids are typically small, motile, and planktonic, swimming with the aid of their swimming legs. They undergo successive molts until reaching the adult form. In parasitic copepods, copepodids are the primary infective instars; they locate and attach to hosts such as fish or invertebrates, where they feed and continue to molt through additional juvenile stages before becoming adults. The copepodid stage is thus a critical transition between the free-living larval form and the sexually mature adult, and its duration and number of molts vary among taxa.

Taxonomically, copepodids refer to any post-naupliar larval stage in copepods, with the exact morphology and behavior differing between free-living and parasitic lineages. The term helps unify descriptions across diverse life histories within Copepoda.