Definition of "nauplius" [‖Nau•pli•us]

• The free-swimming first stage of the larva of certain crustaceans, having an unsegmented body with three pairs of appendages and a single median eye. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "After mating, the eggs undergo brief embryonic development before they are released into the water as nauplius larvae."
• "The nauplius undergoes five moults before it transforms into a copepodite stage that more closely resembles the adult."
• "The eggs are carried in the brood pouch until they hatch into either nauplius or metanauplius larvae."