Mandibulate arthropods typically have sensory/manipulative branches on the postmandibular mouth parts: the maxilla and, if present, labium (2nd maxilla). These palps may be long and somewhat leg-like, reduced to small nubs, or highly modified as stylets or their supports. In entognath arthropods the palps may be withdrawn into the head capsule.
Onychophorans do not have jointed limbs but do have a pair of small processes near the mouth that produce a gluey secretion used to capture and hold prey called oral papillae or glue glands.
Most arachnids have well-developed pedipalps with multiple segments. In some mites (Endeostigmata, Oribatida, and Mesostigmata) palps may have 5 or even 6 segments. A 5-segmented palp consists of the trochanter, femur, genu, tibia, and tarsus. In contrast, a 6-segmented palp results from subdivision of the femur into a basifemur and telofemur. In all mites, the palpal coxae are fused to form the subcapitulum.
All arachnids, except for a few mites, have well developed pedipalps. In many groups of mites the number of free segments is reduced to 1–4.
Author: David E. Walter
Content last updated Sept. 2006, unless indicated otherwise
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