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Themandible (fromLatin:mandibula or mandĭbŭ-lum, a jaw)[1] of anarthropod is a pair ofmouthparts used either for biting or cutting and holding food. Mandibles are often simply called jaws. Mandibles are present in the extantsubphylaMyriapoda (millipedes and others),Crustacea andHexapoda (insects etc.). These groups make up thecladeMandibulata, which is currently believed to be the sister group to the rest of arthropods, the cladeArachnomorpha (Chelicerata andTrilobita).
Unlike thechelicerae ofarachnids, mandibles can often be used to chew food. Mandibulates also differ by havingantennae, and also by having three distinct body regions: head,thorax and abdomen. (Thecephalothorax (or prosoma) of chelicerates is a fusion of head and thorax.)
Insect mandibles are as diverse in form as their food. For instance,grasshoppers and many other plant-eating insects have sharp-edged mandibles that move side to side. Mostbutterflies and moths lack mandibles as they mainly feed on nectar from flowers.
Queen bees have mandibles with sharp cutting teeth unlikeworker bees, who have toothless jaws. Maledobsonflies have slender mandibles up to 2.5 cm long, half as long as the insect's main body.Potter wasps use their mandibles to mix droplets of water with clay while constructing a nest.
Ants have long, broad, serrated jaws, used for digging, collecting food, fighting and cutting, and are probably the most important work tool ants possess. Ants typically bite each other when fighting. Some ants use mandibles to injure the enemy and squirt poison into the wound.Harvester ants use their mandibles to collect and carry seeds.Army ants have sharp mandibles that are better adapted for fighting than obtaining food or nursing thelarvae.Carpenter ants make their nests in various wooden structures, which they hollow out with their sharp mandibles.
The shape and size ofbeetle mandibles varies from species to species depending on the food preferences. For example,carnivorous beetles have extended mandibles to seize or crush prey.Tiger beetles' mandibles (similar to the piercing canine teeth of tigers) are well adapted for killing prey.Diving beetle andfirefly larvae have hollow mandibles, which can inject digestive fluid toliquefy the tissues of the prey. When this process is over, they suck the digested tissue through the mandibles.
Theantlerlike jaws ofstag beetles are essentially their namesake trait. In some tropical species they can be up to 10 cm, as long as the body of the beetle. These mandibles are primarily used in combat.
Caterpillars use sharp mandibles to cut leaves in side-to-side motions. Only a fewmoths have functional mandibles in the adult stage. The most notable example are members of the familyMicropterigidae, small moths with toothed mandibles used for chewingpollen grains, lacking even the most rudimentaryproboscis.
Amongmyriapods,centipedes have strong, bristly mandibles, which have a row of teeth in all centipedes except for members of the order Geophilomorpha. Millipedes have small mandibles, their only functioning mouthparts, as themaxillae are fused to the lower lip (labium).
Crustaceans have a pair of mandibles that typically consist of an enlarged basal segment (coxa) and apalp (sensory feeler) consisting of all other segments. In some groups, such as theBranchiopoda, the palp is reduced or absent. Crustacean mandibles may be equipped with special teeth (molar and incisor processes).