[3] The word Collembola is from Ancient Greek κόλλα kólla 'glue' and ἔμβολος émbolos 'peg'; this name was given due to the existence of the collophore, which was previously thought to stick to surfaces to stabilize the creature.
[4] Early DNA sequence studies[5][6][7] suggested that Collembola represent a separate evolutionary line from the other Hexapoda, but others disagree;[8] this seems to be caused by widely divergent patterns of molecular evolution among the arthropods.
It is located on the fourth abdominal segment of springtails and is folded beneath the body, held under tension by a small structure called the retinaculum (or tenaculum).
Since warmer conditions increase metabolic rates and energy requirements in organisms, the reduction in body size is advantageous to their survival.
[21] The latest whole-genome phylogeny supporting four orders of Collembola:[21] Neelipleona Poduromorpha Symphypleona Entomobryomorpha Springtails are attested to since the Early Devonian.
[24] The fossil from 400 million years ago, Rhyniella praecursor, is the oldest terrestrial arthropod, and was found in the famous Rhynie chert of Scotland.
[37] Springtails are cryptozoa frequently found in leaf litter and other decaying material,[38] where they are primarily detritivores and microbivores, and one of the main biological agents responsible for the control and the dissemination of soil microorganisms.
[39] In a mature deciduous woodland in temperate climate, leaf litter and vegetation typically support 30 to 40 species of springtails, and in the tropics the number may be over 100.
[40] In sheer numbers, they are reputed to be one of the most abundant of all macroscopic animals, with estimates of 100,000 individuals per square meter of ground,[41] essentially everywhere on Earth where soil and related habitats (moss cushions, fallen wood, grass tufts, ant and termite nests) occur.
[43] In addition, a few species routinely climb trees and form a dominant component of canopy fauna, where they may be collected by beating or insecticide fogging.
[42] This is a complex factor embracing both nutritional and physiological requirements, together with behavioural trends,[46] dispersal limitation[47] and probable species interactions.
Some species have been shown to exhibit negative[48] or positive[46] gravitropism, which adds a behavioural dimension to this still poorly understood vertical segregation.
Experiments with peat samples turned upside down showed two types of responses to disturbance of this vertical gradient, called "stayers" and "movers".
[49] As a group, springtails are highly sensitive to desiccation, because of their tegumentary respiration,[50] although some species with thin, permeable cuticles have been shown to resist severe drought by regulating the osmotic pressure of their body fluid.
[59] The horizontal distribution of springtail species is affected by environmental factors which act at the landscape scale, such as soil acidity, moisture and light.
[61] Moisture requirements, among other ecological and behavioural factors, explain why some species cannot live aboveground,[62] or retreat in the soil during dry seasons,[63] but also why some epigeal springtails are always found in the vicinity of ponds and lakes, such as the hygrophilous Isotomurus palustris.
[64] Adaptive features, such as the presence of a fan-like wettable mucro, allow some species to move at the surface of water in freshwater and marine environments.
[42][68] As a consequence of dispersal limitation, landuse change, when too rapid, may cause the local disappearance of slow-moving, specialist species,[69] a phenomenon the measure of which has been called colonisation credit.
Sminthurus viridis, the lucerne flea, has been shown to cause severe damage to agricultural crops,[72] and is considered as a pest in Australia.
[75] However, by their capacity to carry spores of mycorrhizal fungi and mycorrhiza helper bacteria on their tegument, soil springtails play a positive role in the establishment of plant-fungal symbioses and thus are beneficial to agriculture.
[81][82][83][84][85] However, Steve Hopkin reports one instance of an entomologist aspirating an Isotoma species and in the process accidentally inhaling some of their eggs, which hatched in his nasal cavity and made him quite ill until they were flushed out.
[40] In 1952, China accused the United States military of spreading bacteria-laden insects and other objects during the Korean War by dropping them from P-51 fighters above rebel villages over North Korea.
In all, the U.S. was accused of dropping ants, beetles, crickets, fleas, flies, grasshoppers, lice, springtails, and stoneflies as part of a biological warfare effort.
The alleged associated diseases included anthrax, cholera, dysentery, fowl septicemia, paratyphoid, plague, scrub typhus, small pox, and typhoid.
The gene expression profiles of Folsomia candida exposed to environmental toxicants allow fast and sensitive detection of pollution, and additionally clarifies molecular mechanisms causing toxicology.
Laboratory studies have been conducted that validated that the jumping ability of springtails can be used to evaluate the soil quality of Cu- and Ni-polluted sites.
[38] Many springtails, mostly those living in deeper soil horizons, are parthenogenetic, which favors reproduction to the detriment of genetic diversity and thereby to population tolerance of environmental hazards.
[109] Parthenogenesis (also called thelytoky) is under the control of symbiotic bacteria of the genus Wolbachia, which live, reproduce and are carried in female reproductive organs and eggs of Collembola.