A class of the Myriapoda commonly known as the centipedes. As are all myriapods, centipedes are ground dwellers whose permeable cuticle largely restricts their distribution to moist sites and habitats. Centipedes are mostly found under stones, in moss cushions, in leaf litter, and beneath loose bark on trees; several species inhabit caves, especially those of temperate regions. All centipedes are carnivorous; their predatory habits are reflected in their great agility and fleetness and especially in the modification of the first trunk appendages into a pair of usually massive raptorial pincers, the poison claws (also called the forcipules or the prehensors). Each poison claw contains a poison gland whose duct opens near the tip of the claw. Exceptionally, the poison gland may be located in the trunk, in which case the duct connecting it to the apical opening can be as long as twenty body segments. The poison immobilizes or kills arthropod prey and even some small vertebrates. The bite of larger species, particularly of the Scolopendromorpha, may be painful to human beings, but no serious consequences have been reported.