Evolution and systematics
Members of the order Microcoryphia, or Archaeognatha, are superficially comparable to frequent silverfish (order Thysanura). Both have life cycles with out metamorphosis and by no means develop wings. Microcoryphia are true bugs, however they diverged from the principle developmental path main to different insect orders very early in evolutionary time. The order is structurally primitive, retaining many options believed to have been possessed by the ancestral insect. The earliest recognized fossil is from the Lower Devonian interval. There are two trendy households, Machilidae and Meinertellidae, containing roughly 450 species.
Microcoryphia vary in dimension (excluding appendages) from 0.3–0.eight in (7–20 mm). Microcoryphia are cylindrical, with enlarged dorsal thoracic plates, making them seem teardrop formed or humpbacked. The physique is roofed with scales. The title Microcoryphia means “small head.” The head bears a pair of lengthy, threadlike antennae, together with a pair of enlarged maxillary palps that resemble a fourth pair of legs. The eyes are giant, assembly on high of the pinnacle, and may apparently detect motion and type photos. The 10-segmented stomach bears three lengthy, antennalike tail appendages, and ventrally, segments two by way of 9 possess pairs of styli, which help the stomach and allow it to glide easily across the substrate. Pairs of eversible sacs are continuously discovered on belly segments one by way of seven. Common silverfish, in distinction, have flattened our bodies and smaller, broadly separated eyes. Microcoryphia have mandibles with just one level of articulation, comparable in construction to these of noninsect hexapod teams such because the springtails (order Collembola). All different true bugs, together with silverfish, have mandibles with two factors of articulation.
Microcoryphia are recognized from all continents besides Antarctica, and are distributed from sea degree to 15,750 ft (4,800 m) within the Himalayas.
Most Microcoryphia dwell close to the bottom, on the floor of the soil, in leaf litter, and on or beneath rocks. Species inhabiting tropical rainforests are sometimes partially or solely arboreal.
Activity in numerous species is crepuscular or nocturnal. Many species are recognized to mixture, and these aggregations could encompass members of a number of species and genera from the identical household, however not from totally different households. Individuals appear to comply with sure paths and routes. Chemical indicators could also be vital in path forming and aggregating conduct. Microcoryphia bounce by bending and instantly releasing the tip of the stomach, placing it towards the bottom. These bugs are additionally wonderful climbers, utilizing their belly styli to anchor themselves whereas they transfer like an inchworm up vertical surfaces.
Feeding ecology and weight loss plan
Microcoryphia are herbivores, feeding on algae, fungi, lichens, and leaf litter.
Elaborate tactile courtship conduct usually happens between pairs, involving particular sensory buildings. There are three frequent strategies of sperm switch. In the primary, the provider thread methodology, males spin a thread between the bottom and the elevated tip of the stomach. Sperm droplets are placed on the thread, which females accumulate with the ovipositor. In the second methodology, the male attaches a sperm packet to the bottom. He then pushes his head and thorax under the feminine, “pick-a-back” model, and maneuvers her over the sperm packet, whereupon she takes it up together with her ovipositor. In the third methodology, the female and male elevate the tips of their abdomens and produce them into contact, aligning themselves at a 45° angle. The male deposits a sperm droplet onto the ovipositor of the feminine. Females lay eggs in protected locations, often cementing them to the substrate. Development typically progresses by way of six to eight instars. Adults proceed to molt, an ancestral attribute enabling regeneration of misplaced appendages. Individuals could dwell up to three years, and molt as many as 60 occasions.
No species of Microcoryphia is listed by the IUCN.