Morphology of the Nervous System of Barnacles: the Median Ocellus of Balanus Hameri (=Chirona Hameri) (Crustacea: Cirripedia)

The barnacle cypris larva possesses a pair of laterally placed compound eyes and a median nauplius eye which is tripartite in structure. Concomitant with the metamorphosis to the juvenile is the loss of compound eyes and the nauplius eye separates into its three constituent parts (Walley, 1969). The two dorsolateral components of the nauplius eye come to lie under the rostral shell plates, whereas the ventral component forms the median ocellus which underlies the mantle flaps of the scutal plates at the posterior margin of the adductor muscle (Figure 1).