250px, The mandibles of a bull ant The mandible (from la, mandibula or mandĭbŭ-lum, a jaw) of an

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

is a pair of mouthparts used either for biting or cutting and holding food. Mandibles are often simply called jaws. Mandibles are present in the extant subphyla

Myriapoda Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. The fossil record of myriapods reaches back into the late Silurian ...

(millipedes and others), Crustacea and

Hexapoda The subphylum Hexapoda (from Greek for 'six legs') comprises most species of arthropods and includes the insects as well as three much smaller groups of wingless arthropods: Collembola, Protura, and Diplura (all of these were once considered ins ...

(insects etc.). These groups make up the clade

Mandibulata Mandibulata, termed "mandibulates", is a clade of arthropods that comprises the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others). Mandibulata is currently believed to be the sister group of the clade ...

, which is currently believed to be the sister group to the rest of arthropods, the clade

Arachnomorpha Arachnomorpha is a proposed subdivision or clade of Arthropoda, comprising the group formed by the trilobites and their close relatives (Artiopoda), Megacheira (which may be paraphyletic) and chelicerates. Under this proposed classification sch ...

(

Chelicerata The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It contains the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mi ...

and

Trilobita Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

). Unlike the

chelicerae The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as " jaws", chelicerae may be shaped as either articulated fangs, or similarl ...

arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...

s, mandibles can often be used to chew food. Mandibulates also differ by having antennae, and also by having three distinct body regions: head,

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

and abdomen. (The cephalothorax (or prosoma) of chelicerates is a fusion of head and thorax.)

Insects

Insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

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. Most butterflies and moths lack mandibles as they mainly feed on nectar from flowers.

Queen bee A queen bee is typically an adult, mated female ( gyne) that lives in a colony or hive of honey bees. With fully developed reproductive organs, the queen is usually the mother of most, if not all, of the bees in the beehive. Queens are developed ...

s have mandibles with sharp cutting teeth unlike

worker bee A worker bee is any female (eusocial) bee that lacks the full reproductive capacity of the colony's queen bee; under most circumstances, this is correlated to an increase in certain non-reproductive activities relative to a queen. While worker be ...

s, who have toothless jaws. Male

dobsonflies Dobsonflies are a subfamily of insects, Corydalinae, part of the Megalopteran family Corydalidae. The larvae (commonly called hellgrammites) are aquatic, living in streams, and the adults are often found along streams as well. The nine genera o ...

have slender mandibles up to 2.5 cm long, half as long as the insect's main body.

Potter wasp Potter wasps (or mason wasps), the Eumeninae, are a cosmopolitan wasp group presently treated as a subfamily of Vespidae, but sometimes recognized in the past as a separate family, Eumenidae. Recognition Most eumenine species are black or brown, ...

s use their mandibles to mix droplets of water with clay while constructing a nest.

Ants

Ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

s 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 ant Harvester ant, also known as harvesting ant, is a common name for any of the species or genera of ants that collect seeds (called seed predation), or mushrooms as in the case of '' Euprenolepis procera'', which are stored in the nest in commu ...

s use their mandibles to collect and carry seeds.

Army ant The name army ant (or legionary ant or ''marabunta'') is applied to over 200 ant species in different lineages. Because of their aggressive predatory foraging groups, known as "raids", a huge number of ants forage simultaneously over a limi ...

s have sharp mandibles that are better adapted for fighting than obtaining food or nursing the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

Carpenter ant Carpenter ants (''Camponotus'' spp.) are large () ants indigenous to many forested parts of the world. They build nests inside wood consisting of galleries chewed out with their mandibles or jaws, preferably in dead, damp wood. However, unl ...

s make their nests in various wooden structures, which they hollow out with their sharp mandibles.

Beetles

The shape and size of

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

mandibles varies from species to species depending on the food preferences. For example, carnivorous beetles have extended mandibles to seize or crush prey.

Tiger beetle Tiger beetles are a family of beetles, Cicindelidae, known for their aggressive predatory habits and running speed. The fastest known species of tiger beetle, ''Rivacindela hudsoni'', can run at a speed of , or about 125 body lengths per second. ...

s' mandibles (similar to the piercing canine teeth of tigers) are well adapted for killing prey. Diving beetle and firefly larvae have hollow mandibles, which can inject digestive fluid to liquefy the tissues of the prey. When this process is over, they suck the digested tissue through the mandibles. The antlerlike jaws of stag 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.

Butterflies and moths

Caterpillars use sharp mandibles to cut leaves in side-to-side motions. Only a few

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

s have functional mandibles in the adult stage. The most notable example are members of the family

Micropterigidae Micropterigoidea is the superfamily of "mandibulate archaic moths", all placed in the single family Micropterigidae, containing currently about twenty living genera. They are considered the most primitive extant lineage of lepidoptera (Kristense ...

, small moths with toothed mandibles used for chewing pollen grains, lacking even the most rudimentary

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

Myriapods

Among

myriapods Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. The fossil record of myriapods reaches back into the late Silurian, ...

, 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 the maxillae are fused to the lower lip ( labium).

Crustaceans

Crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s have a pair of mandibles that typically consist of an enlarged basal segment (coxa) and a

palp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") ...

(sensory feeler) consisting of all other segments. In some groups, such as the

Branchiopoda Branchiopoda is a class of crustaceans. It comprises fairy shrimp, clam shrimp, Diplostraca (or Cladocera), Notostraca and the Devonian ''Lepidocaris''. They are mostly small, freshwater animals that feed on plankton and detritus. Description ...

, the palp is reduced or absent. Crustacean mandibles may be equipped with special teeth (molar and incisor processes).

References

*Encarta Reference Library Premium 2005 DVD. {{cite journal , author1=Lars Reindhart , author2=Kevin Weiβing , author3=Tobias Siebert , author4=Benjamin Wipfler , title=Fast and Powerful: Biomechanics and Bite Forces of the Mandibles in the American Cockroach Periplaneta americana , journal=PLOS ONE , date=November 11, 2015, volume=10 , issue=11 , pages=e0141226 , doi=10.1371/journal.pone.0141226 , pmid=26559671 , pmc=4641686 , doi-access=free Mouth Arthropod anatomy