Zoea is the larval stage shared by many crabs before they become later larvae or juveniles. A zoea typically has prominent spines and appendages that help it swim and remain suspended in plankton-rich water.
Crab development commonly begins when eggs hatch into planktonic larvae. Depending on the species, a zoea may pass through several moults before becoming a megalopa, a later stage that resembles a small crab more closely. It eventually settles and develops into a juvenile crab.
The exact sequence varies among crab groups. Some species hatch at a more advanced stage, while others have abbreviated development or omit stages found in related crabs. Water temperature, food supply, salinity, and currents strongly influence larval survival.
Zoea should not be confused with a nauplius, the early larval form of many crustaceans such as copepods, or a veliger, a larva of many molluscs. These terms identify different developmental forms in different animal groups.