Pedipalp

The pedipalps are the second pair of appendages of arachnids (spiders, scorpions, mites, harvestmen, and related organisms). They are located near the mouthparts and anterior to the first pair of walking legs. Pedipalps are modified in various ways in different arachnid orders, serving a range of functions including sensory perception, prey capture, manipulation, copulation, and defense.

In scorpions, the pedipalps are developed into large pincers (chelae) used for grasping prey and defense. In spiders, the pedipalps are typically smaller and more leg-like in females, functioning primarily as sensory organs. However, in male spiders, the pedipalps are often modified as complex structures used for transferring sperm to the female during mating. These structures can be highly species-specific, acting as a "lock and key" mechanism to ensure reproductive compatibility. Mites and harvestmen also exhibit diverse pedipalp morphologies, adapted for feeding, sensing, and other functions specific to their lifestyles.