Evolution, Morphology, and Development of the Centipede Venom System

Abstract

With approximately 3,500 species distributed across five extant orders, centipedes (class Chilopoda) make the second most speciose class among the subphylum Myriapoda. The most conspicuous synapomorphic character of centipedes is certainly the modification of the first pair of legs into powerful venomous forceps (the forcipules). The venom gland encased in each forcipule produces a potent cocktail of paralytic toxins delivered into prey and opponents via a cuticular duct which opens on the subterminal part of the apical claw. It has been hypothesized that this modification, unique in the animal world, results from the folding of the outer cuticle of the walking legs and the transformation of related subepidermal gland units into venom-producing cells as an adaptation to a new terrestrial predatory niche over 430 million years ago, thus making centipedes one of the most ancient known clade of terrestrial venomous organisms. However, despite their global distribution, synanthropic habits, and reputation for inflicting painful stings, little is known about centipedes and their venom system. This chapter reviews the current knowledge on the development, the evolutionary trajectory, the anatomy, the physiology, and the predatory ecology of centipedes, with a strong emphasis on the forcipular apparatus.