Development
Apart from parasitic species, mature cirripedes are typically hermaphroditic, but normally crossfertilise.
Embryos develop within the ovaries and are released in high numbers as nauplius larvae
(Figs. 1A, 2). In at least some parasitic and Scalpelliformes species, the nauplii are retained and
released as the later developmental stage, the cyprid larvae (Fig. 1B). Nauplii superficially
resemble copepod nauplii and also moult through a series of naupliar stages, from four to six
depending on species, increasing in size between each (Fig. 2). They can easily be distinguished
from other crustacean nauplii by the presence of two prominent frontolateral horns on their
characteristically rounded cephalic shield (carapace). At least the first nauplius stage (N1) is
lecithotrophic, non-feeding, obtaining enough nutriment from the yolk to carry it through to the
second stage when it can start feeding in the plankton. However, in some groups all the naupliar
stages are lecithotrophic.