Practice question

Nauplius is diagnostic first free larval stage of Crustacea exhibiting unsegmented ovoid body, single median naupliar eye, and three pairs of appendages: first antennae antennules for swimming, second antennae and mandibles. It swims using second antennae, feeds on yolk or microplankton depending on lecithotrophic or planktotrophic mode, then molts through successive stages adding trunk segments, thoracic appendages, compound eyes developing into metanauplius, protozoea, zoea and mysis in decapod sequence. Veliger characterizes molluscs, trochophore annelids and molluscs, pilidium nemerteans. Nauplius therefore marks crustacean development and dispersal.