Image Key > Copepoda > Crustacean Nauplii

• Earliest and most basic type of a crustacean larva is the nauplius.
• Development in the 1st naupliar stage is minimal, with only 3 pairs of appendages present – the 1st antennae, the second antennae and the mandibles.
• During successive moults, trunk segments and additional appendages are usually added.
• There is no segmentation of the body and a single eye (naupliar eye) in the centre of the head is present.
• Nauplii are often extremely abundant in plankton samples and are generally from copepods, but can occasionally be from barnacles.
• Barnacle nauplii are easily distinguishable because they possess a pair of ‘horns’ at the front of the head (image 2).
• It is very difficult to separate nauplii into species and often they are lumped together as a single group.