The Role of Suction in the Adhesion of Limpets

ABSTRACT Experiments were performed to determine the mechanism by which limpets attach to the substratum. Pressure measurements were made under the feet of three species of limpets as they were forcibly detached from the substratum. These measurements show that limpets actively decrease the pressure under their feet, and in almost every case this pressure decrease can account for all of their tenacity. The results are the same whether the pressure transducer is flush with the surface or connected to the surface via a tube. The tenacity of limpets is dependent on ambient pressure, as predicted for a suction mechanism. Leaks disrupt the attachment of limpets. Thus, for at least an hour after they have been moving, suction appears to be the primary attachment mechanism of limpets. Limpets using suction often have tenacities greater than 0.1 MN m−2, which corresponds to pressures under the foot lower than 0MPa. If limpets have more than a few hours to attach, approximately 30% of them form a different, stronger attachment that appears to be based on glue. These limpets remain stationary for extended periods. It is hypothesized that limpets in the field alternate between the use of suction and glue, depending on their need for mobility.