noninsect

Noninsect is an informal term used to refer to all organisms that are not members of the class Insecta. In biology, Insecta is a highly diverse group within the arthropods, characterized by a three-part body plan and typically six legs, but the noninsects feature far greater diversity. The term is not a formal taxonomic category and is mainly used in ecological or comparative discussions to distinguish insects from other life forms.

Noninsects comprise a wide range of groups. Among animals, major noninsect groups include arachnids (such as spiders and scorpions), myriapods (centipedes and millipedes), and crustaceans (crabs, lobsters, shrimp, and copepods), as well as non-arthropods such as mollusks (snails, clams, octopuses), annelids (earthworms, leeches), echinoderms (starfish, sea urchins), and chordates (fishes, amphibians, reptiles, birds, mammals). Beyond animals, plants, fungi, and many microorganisms are also noninsects, illustrating the breadth of life outside Insecta.

Within hexapods, insects are the largest group, but some classifications treat springtails and other basal hexapods as noninsects. This reflects the fluid nature of taxonomy and the informal use of "noninsect" in some disciplines.

Ecologically, noninsects occupy diverse roles: predators, grazers, scavengers, detritivores, and ecosystem engineers. They are found in nearly every habitat, from oceans to deserts, and from deep soils to canopies. The term underscores the diversity of life beyond insects in studies of biodiversity and ecology.