Adhesive secretions in harvestmen (arachnida: Opiliones)

Opiliones, colloquially also known as harvestmen or daddy longlegs, are arachnids capable of producing and releasing a variety of secretions that are used to deter predators. The fact that a large fraction of these animals also produce efficient glues for trapping prey, gluing eggs to substrates, attaching soil particles to their body or eggs for camouflage purposes, or transferring sperm, is rather unknown. Not only the physical properties of these glues are interesting, but also the supplementary cuticular structures, that work hand in hand with the secretions to produce highly efficient adhesive mechanisms. Here we give an overview on the occurrence, properties, and associated structures of adhesive secretions in harvestmen and discuss their biological functions.