ABSTRACT
Jasus edwardsii has eleven phyllosoma larvae that are morphologically adapted for a planktonic existence. These are followed by a puerulus stage which, although it has the general body form of the adult, is also adapted for swimming. The next moult is the first of the truly benthic juvenile stages. Using transmission electron microscopy we compared transverse sections of connectives in the ventral nerve cord of the first phyllosoma, the puerulus and the first post-puerulus stage at a number of points. We found that the anterior cord of the phyllosoma has approximately the same number of neurons as the puerulus. This has implications for our understanding of crustacean larval sensory systems because previous work shows that most fibres in the adult nerve cord are sensory. Fibre counts in the post-puerulus increase in the expected manner. The cord structure of the puerulus and post-puerulus is the same as that found in the adult whereas that of the early phyllosoma is not.
