Collembola

• The word “Collembola” is from the 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 in order to stabilize the creature.
• Springtails ( Collembola ) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Entognatha because they have internal mouthparts, they do not appear to be any more closely related to one another than they all are to insects, which have external mouthparts
• Members of Collembola are normally less than 6 mm (0.24 in) long, have six or fewer abdominal segments and possess a tubular appendage (the collophore or ventral tube) with eversible sticky vesicles, projecting ventrally from the first abdominal segment. Collembola lack a tracheal respiration system, which forces them to respire through a porous cuticle, with the notable exception of Sminthuridae which exhibit a rudimentary, although fully functional, tracheal system (Davies et al., 1927).
• Collembolans are omnivorous, free-living organisms that prefer moist conditions. They do not directly engage in the decomposition of organic matter, but contribute to it indirectly through the fragmentation of organic matter (Brady et al., 2009) and the control of soil microbial communities (Thimm et al., 1998).
• Some DNA sequence studies (Delsuc et al., 2003; Nardi et al., 2003) suggest that Collembola represent a separate evolutionary line from the other Hexapoda, but others disagree (Gao et al., 2008) this seems to be caused by widely divergent patterns of molecular evolution among the arthropods (Hassanin et al., 2006).
• The adjustments of traditional taxonomic rank for springtails reflects the occasional incompatibility of traditional groupings with modern cladistics: when they were included with the insects, they were ranked as an order; as part of the Entognatha, they are ranked as a subclass. If they are considered a basal lineage of Hexapoda, they are elevated to full class status.
• Springtails commonly consume fungal hyphae and spores, but also have been found to consume plant material and pollen, animal remains, colloidal materials, minerals and bacteria(Chen et al., 1996). Springtails are cryptozoa frequently found in leaf litter and other decaying material (Hopkin et al., 1997) where they are primarily detritivores and microbivores, and one of the main biological agents responsible for the control and the dissemination of soil microorganisms (Ponge et al., 1991). 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 (Hopkin et al., 1997).

References:

Delsuc, Frédéric; Phillips, Matthew J. & Penny, David (2003). “Comment on Hexapod origins: monophyletic or paraphyletic?” ( PDF ). Science . 301 (5639): 1482. doi : 10.1126/science.1086558 . PMID 12970547 .

Nardi, Francesco; Spinsanti, Giacomo; Boore, Jeffrey L.; Carapelli, Antonio; Dallai, Romano & Frati, Francesco (2003). “Hexapod origins: monophyletic or paraphyletic?” ( PDF ). Science . 299 (5614): 1887–1889. doi : 10.1126/science.1078607 . PMID 12649480 .

Gao, Yan; Bu, Yun & Luan, Yun-Xia (2008). “Phylogenetic relationships of basal hexapods reconstructed from nearly complete 18S and 28S rRNA gene sequences” ( PDF ). Zoological Science . 25 (11): 1139–1145. doi : 10.2108/zsj.25.1139 . PMID 19267625

Hassanin, Alexandre (2006). “Phylogeny of Arthropoda inferred from mitochondrial sequences: strategies for limiting the misleading effects of multiple changes in pattern and rates of substitution” ( PDF ). Molecular Phylogenetics and Evolution . 38 (1): 100–116. doi : 10.1016/j.ympev.2005.09.012 . PMID 16290034

Davies, W. Maldwyn (1927). “On the tracheal system of Collembola, with special reference to that of Sminthurus viridis, Lubb” ( PDF ). Quarterly Journal of Microscopical Science . 71 (281): 15–30.

Chen, Benrong; Snider, Richard J. & Snider, Renate M. (1996). “Food consumption by Collembola from northern Michigan deciduous forest” ( PDF ). Pedobiologia. 40 (2): 149–161.

Hopkin, Stephen P. (1997). “The biology of the Collembola (springtails): the most abundant insects in the world” ( PDF ). Natural History Museum . Retrieved January 2, 2016.

Ponge, Jean-François (1991). “Food resources and diets of soil animals in a small area of Scots pine litter” ( PDF ). Geoderma. 49 (1–2): 33–62. doi : 10.1016/0016-7061(91)90090-G .

Hopkin, Stephen P. (1997). Biology of the Springtails: (Insecta: Collembola) . OUP Oxford. p. 127. ISBN 978-0-19-158925-6