Nauplius larvae. The genus name Nauplius was published posthumously by Otto Friedrich Muller in 1785 for animals now known to be the larvae of copepods. The nauplius stage (plural: nauplii) is characterized by the use of the appendages of the head (the antennae) for swimming. The nauplius is also the stage at which a simple, unpaired eye first appears. The eye is known for that reason as the naupliar eye, and is often absent in later developmental stages, although it is retained into the adult form in some groups, such as the Notostraca. This image has been color enhanced.