Archaeognatha

Archaeognatha, commonly known as jumping bristletails, is an order of small, wingless insects that are among the most primitive living insects. Adults typically measure 10–25 millimeters in length and have a cylindrical, arched body, a broad head, and long antennae. The eyes are large and often meet at the midline. A distinctive feature is their monocondylic mandibles, a primitive jaw joint, and three long tail filaments: two cerci and a central epiproct.

Archaeognatha are capable of rapid jumping, using a flexed abdomen and a spring-like action to launch themselves from surfaces. They move quickly on damp substrates such as leaf litter, bark, and rocks. They lack wings and scales on the body, and have reduced, robust legs suited for running and gripping uneven surfaces.

Ecology and diet: They are detritivores and omnivores, feeding on algae, lichens, decaying plant matter, and microfungi. They prefer moist, shaded habitats and are often active at night or in dim light.

Reproduction and development: Archaeognatha undergo ametabolous development; juveniles resemble adults and molt through several instars. Eggs are laid in sheltered microhabitats, and there is no pupal stage.

Systematics: The order contains two living families, Machilidae and Meinertellidae, with a cosmopolitan distribution in temperate and tropical regions. The group is considered among the most primitive extant insects, and its anatomy provides insight into early insect evolution.