Mouthparts

Mouthparts are the structures around the opening of the mouth that animals use to seize, manipulate, and process food. In arthropods, mouthparts are particularly diverse and have evolved to match feeding strategies. In insects, the typical adult head bears a labrum (upper lip), paired mandibles for biting or grinding, a pair of maxillae often bearing sensory palps, and a labium forming the lower lip, sometimes with glossal and palpal elements. A hypopharynx may function as a tongue or salivary channel. The arrangement can be highly specialized for particular diets.

Functional categories include chewing (mandibles and surfaces for grinding, common in beetles and many caterpillars), piercing-sucking (stylets formed from modified mandibles and maxillae, seen in aphids, cicadas, and mosquitoes), siphoning (elongated proboscis in Lepidoptera), sponging (labella on the labium in some Diptera), and lapping (mouthparts adapted to lap up liquids). The specific configuration often determines dietary capabilities and feeding behavior.

Other arthropods show analogous diversity. Crustaceans typically have mandibles and maxillipeds; arachnids use chelicerae and pedipalps to grasp and macerate prey. Mouthparts may be partly externalized and can vary with development or life stage, as in many holometabolous insects whose larval and adult mouthparts differ according to ecological niches.

Because mouthparts reflect feeding ecology, they are important for taxonomy and functional morphology. Studying their structure helps explain how organisms exploit different food sources, from solid plant and animal matter to liquids.