Zoea

Zoea is a larval stage of many crustaceans, especially decapod crustaceans such as crabs, lobsters, and shrimps. It follows the nauplius stage and precedes later larval instars (such as mysis in shrimps or megalope in crabs), with several zoea molts in many species. Zoea larvae are free-swimming, planktonic organisms that inhabit coastal, estuarine, and open-marine waters depending on species. They primarily feed on phytoplankton and microcrustaceans and contribute to the planktonic phase of the life cycle.

Morphology: The zoea is typically characterized by a broad shield-like carapace covering the cephalothorax, often bearing spines or projections along the margins. Eyes are usually on stalks, and the animal has specialized swimming appendages. The abdomen is often slender, and the tail fan (telson with uropods) aids locomotion. Features used for species identification include carapace shape, spination, and the arrangement of mouthparts and appendages.

Development and ecology: Zoea development is influenced by environmental conditions such as temperature and salinity, and the number of instars varies by species. After successive molts, the zoea transitions into the next larval stage, and eventually to postlarval or juvenile forms that resemble adults. The zoea stage is important for larval dispersal and survival, affecting recruitment and population dynamics in commercially important crustaceans. Researchers study zoea morphology and distributions to understand life histories, larval ecology, and fisheries management.