To achieve their reproductive potential, barnacles combine tactile exploration of surface structural properties and integration of cellular signals originating from their antennular sensory setae within a developmentally defined, temporally narrow window of settlement opportunity. Behavioural assays with cyprids coupled with biometric analysis of scanning electron microscopy-acquired images in the presence of specific chemical compounds were used to investigate how settlement on a substratum is altered in response to the presence of these compounds. It is shown that impeding tactile exploration, altering cellular signalling and/or inducing malformations of anatomical features of the antennular sensory setae can disrupt the settlement behaviour of the model barnacle species Amphibalanus amphitrite. It is concluded that surface exploration by the cyprids relies on mechanical and nociception-related and calcium-mediated signals while a protein kinase C signalling cascade controls the timely metamorphosis of the cyprids to sessile juveniles.
Keywords: 20E: 20-hydroxyecdysone; AD: attachment disc; ADS: axial disc seta; AS2–4: antennular segments 2–4; ASW: artificial sea water; Amphibalanus amphitrite; BITC: benzyl isothiocyanate; Bp: basis; CH: cuticular basal hair; FF: frontal filament; FP: frontal horn pore; JH: juvenile hormone; JHAMT: juvenile hormone acid O-methyltransferase; MF: methyl farnesoate; PDE: 3′,5′-cyclic nucleotide phosphodiesterases; PRS2: preaxial seta 2; PS2–3: postaxial setae 2–3; RDS3–5: radial disc setae 3–5; SEM: scanning electron microscopy; STS1-4: subterminal setae 1–4; TS-A–E: terminal setae A–E; Th1–6: thoracopods 1–6; barnacles; biofouling; ecdysteroids; juvenile hormone; metamorphosis.