Barnacle ecology and adaptation

Intertidal barnacles have been well studied for their adaptations for shore life and as members of shore communities. However, many more species occur sublittorally. The distribution of thoracicans is viewed in evolutionary time as escape from predatory and competitive pressures in shallow seas — to intertidal refugia, commensalism or deep-sea existence, with appropriate adaptations. Existence in shallow seas is favoured by development of fugitive characteristics, mainly involving reduction of generation time and enhanced fecundity. Such barnacles are the typical fouling species and include lepads of oceanic environments and balanids of coastal situations. With euryhaline adaptations, a few balanid species live in brackish or hypersaline lagoons beyond marine prédation and competition.