palp A sensory appendage situated near the mouth of many invertebrates. In Arthropoda, it is a jointed, sensory structure that articulates with the labium or maxillae. See also LABIAL PALP; MAXILLARY PALP.

palp An elongated sensory organ, usually near the mouth, in many invertebrates. Examples are the tactile head appendages of polychaete worms, the ciliated flap of tissue that produces feeding currents in bivalve molluscs, the distal part of the mandibles of crustaceans, and the olfactory parts of the first and second maxillae of some insects.