Crustaceans are Arthropods whose body is covered with chitinous exoskeleton for protection. But the same exoskeleton does not allow body growth and hence must be shed in order to allow growth. The larval stages feed and grow in order to become adults and must undergo moulting or ecdysis to grow. After each moulting they change their structure and size and hence are different from the previous stage. Therefore, each species of crustaceans demonstrates several successive larval stages before it becomes adult.
NAUPLIUS LARVA. Discovered by Muller in 18th century, the Nauplius larva is the first fundamental stage in all crustaceans that sometimes hatches from the egg and sometimes passes inside the egg. ...
METANAUPLIUS LARVA. ...
PROTOZOEA LARVA. ...
ZOEA LARVA. ...
MYSIS LARVA. ...
SCHIZOPODA LARVA. ...
PHYLLOSOMA LARVA.
ALIMA LARVA


According the biogenetic law proposed by Haeckel, ontogeny recapitulates phylogeny. This in other words means that, the successive stages of individual development correspond with successive ancestors in the line of evolutionary descent. Nauplius larva occurs in the development of all the crustaceans and so it was considered as the ancestral form of crustaceans. The old idea of recapitulations stands greatly modified now-a-days and the crustacean larval forms are now regarded to be the larval reversions of simpler crustacean ancestors.

The larval forms are useful for finding out homologies and the affinities among various groups. The animals which pass through similar stages are closely related. Larvae are helpful in wide range distribution of species and also in keeping the food reserves of eggs to a minimum.