palp

noun

In certain polychaete annelids, a sensory outgrowth (sometimes consisting of 2 units) of the ventral or frontal side of the prostomium; in some other polychaetes, a long sensory outgrowth of the first true segment; in Crustacea and other arthropods, the slender distal portion of mandible or maxilla, which functions as a sensory structure.