Abstract
Tarsal morphology of spiders differs from species to species, reflecting adaptations to habitat demands. Jumping spiders (Salticidae) rely on the hierarchically structured claw tuft (scopula) to firmly attach to smooth surfaces. This scopula consists of single hairs (setae) covered by numerous cuticular processes (setules). These setules are the direct contacting elements of the attachment system. Adhesion does not depend on secreted fluids but employs short-ranging van der Waals forces. The estimated 624,000 setules in the spider Evarcha arcuata allow for a theoretical safety factor of 160 times the spider's average weight. Strong adhesion is balanced by easy detachment through an asymmetric design of the setules' distal ends. Detachment is controlled in an integrated manner via leg kinematics. The combination of dry adhesion, functional also in vacuum, substrate compliant hierarchical structure, and switchable adhesive properties, perfectly qualifies for biomimetic transfer. To be able to transfer the adhesive performance like the one of the salticid spider E. arcuata to a technical design, it is necessary to analyze the individual contributions of adhesion, compliance, and detachment.