Cyprid larvae of the acorn barnacle Semibalanus balanoides (Linnaeus, 1767) (Cirripedia: Sessilia: Archaeobalanidae) can metamorphose to juveniles without being permanently attached to a substrate

Abstract

Abstract It is commonly assumed that the pelagic cyprid larvae of acorn barnacles must permanently attach to a substrate before metamorphosing to the benthic juvenile stage. We show that this is not always the case and demonstrate that some cyprids can metamorphose in the water column, i.e. without first becoming cemented to a surface. We observed early-metamorphosing cyprids to fully developed juveniles in coastal plankton samples during the 2018 recruitment season of Semibalanus balanoides (Linnaeus, 1767) in Atlantic Canada. We demonstrated through a laboratory experiment that cyprids can be induced to fully metamorphose into pelagic juveniles. These novel findings raise the question of whether this phenomenon may also occur in other barnacle species.