A palp (lat. Palpare "caress, touch" palpus "button", plural palpi ) is a button on the mouthparts of different animal groups. For example, palpi can be found on various poly bristles , insects , arachnids and crustaceans . They are always arranged in pairs. In some groups of animals, such as B. the beetles and butterflies a distinction is made between lip palps (palpus labialis or labial palps) and mandibular palps (palpus maxillaris or maxillary palps ). The former are attached to the lower lip, the labium , the latter to the lower jaw, the maxilla .
The term button is misleading in that many animals do not just use it to touch . Often the palpi have a thick hair , which can be not only whiskers but also contact chemoreceptors . They can also be used for tasting and smelling .
Pedipalps are multifunctional organs of the arachnids (arachnida). They can be used for communication ( stridulation or substrate vibrations, network vibrations, optical signals), but also for courtship, mating ( weaving spiders ) or locomotion ( palm trees ). Pedipalps can be pronounced as scissors ( scorpions ) or as biting or drilling tools ( mites ).
For insects and spiders, the shape, position and internal fine structure of the palpi or their presence or absence are used as identifying features.