Springtails (scientific name Collembola) are six-legged relatives of insects. They get their name by the presence of a springing mechanism ("furca") tucked up under their abdomen that allows them to launch themselves a distance that equals many times their body length.

Worldwide, about 6,500 species thus far have been described. Prior to the ATBI we had 44 species of Springtails in the Smokies. Now, we have a total of 252! Of these, 59 are completely new to science, and an additional 129 are new records for the Park!

Description:
Collembola (springtails) have long been considered insects; however, morphological, molecular, and fossil evidence strongly suggests that they are a separate class related to insects.
Some recent analyses have even placed them as derivatives of Crustacea.
Collembola are entognathous (mouthparts held within a buccal cavity of the head) apterygotes (without wings), ranging in size from 0.25 mm (Megalothorax minimus) to 10 mm (some species of neanurids).
About 6,500 species have been described and there might be close to 50,000 species of Collembola on earth.
Every springtail has a ventral tube or collophore.
It was originally thought that this tube secreted a sticky substance, aiding in surface adhesion. This distinctive character led to the name Collembola, originating from the Greek roots colle (=glue) and embolon (=piston). Although it does serve a purpose similar to this in some species, the main function of the ventral tube is regulating fluid balance. Due to this function the collophore is one of the main sites for the uptake of pesticides in the soil environment (Founatin & Hopkin 2005).
Collembola are often called springtails due to the presence of a furcula (Figures 1-3, 5), which they use for jumping. The furcula evolved from the fusion of a pair of appendages on the fourth abdominal segment, and serves as a way for springtails to escape from predators. In semiaquatic species the mucro widens, increasing the surface area in contact with the water surface and enabling these species to spring further when on the water. ◦The furcula often is greatly reduced or missing in species that live within the soil.

Habits of Collembola:
Most species feed on leaf detritus and fungal hyphae; however, some are carnivorous and consume nematodes, rotifers, and other Collembola (Chahartaghi, et al 2005).
A few species eat living plant tissue and can cause crop damage (alfalfa, clover) (See Ecological Impact below). Collembola also have been documented feeding on human corpses in the beginning stages of decomposition. Recent research is employing PCR-based techniques to identify specific prey species in the guts of predatory Collembola (Read, et al 2006). Another current study used nitrogen stable isotopes to identify different feeding guilds of Collembola. The three main guilds were phycophages/herbivores, and primary and secondary decomposers (Chahartaghi, et al 2005). This study also concluded that the same species in different habitats might have different diets, implying that some Collembola have the ability to switch their diets based on available resources (Chahartaghi, et al 2005).

Distribution and Habitat:
Springtails are distributed worldwide. They live on every continent and have been found at the most southerly location ( Antarctica, 84˚ 47? S, Biscoia sudpolaris (Hypogastruridae) and Antarctophorus subpolaris (Isotomidae)) of any arthropod. Species richness and diversity are higher in humid and mesic environments (Rusek 1989); however, they can live in deserts in Australia (Folsomides arnoldi (Isotomidae)) as well as on the snow in the Himalayas (Aackia karakoramensis (Isotomidae)).

Life processes of Collembola occur at different rates based on available food sources (van Amelsvoort and Usher 1989). This plasticity, even within species, might enable springtails to occupy this wide variety of habitats.

The majority of Collembola inhabit moist, terrestrial habitats such as damp leaf litter; yet a small percentage is considered to be semiaquatic or riparian (Thorp & Covich 1981). Certain species have cuticular adaptations or the ability to enter anhydrobiosis, which enables them to tolerate drought in xeric environments (Lawrence & Massoud 1973). Within the same species there are different levels of drought resistance at different developmental stages (Betsch & Vannier 1977).

Although Collembola prefer moist environments, too much water can also be a problem. Species that occur in floodplain habitats have adaptations for dealing with excess water. Collembola have a higher survival rate during spring floods, when water temperatures are low and oxygen levels are high, as opposed to summer floods (density reduced by 89%) (Rusek 1989).

The euedaphic (living in the lowest soil layers (Eisenbeis, G. & Wichard, W. 1987)) species are affected more than the epedaphic (living in the upper soil and litter layers (Eisenbeis, G. & Wichard, W. 1987)) or atmobiotic (living on the soil surface, including herbaceous, shrub and tree layers (Eisenbeis, G. & Wichard, W. 1987)) species (Rusek 1984). Certain species survive the floods in an egg stage while others recolonize from areas that were not flooded (Rusek 1989).

Collembola are also able to tolerate a wide range of temperatures, on average from 5 to 15˚C, but with extremese of -2 and 28˚C in some species.

As with flooding, certain species deal with low temperatures by overwintering as eggs (Sminthuridae, Bourletiellidae, Dicyrtomidae, Entomobrya spp., and Lepidocyrtus spp.). However, other Collembola have evolved to tolerate freezing. These species maintain their body fluids in a liquid state below freezing using polyhydric alcohols and sugars (Rusek 1989). Reproduction Collembola reproduce by means of eggs (Figure 6). Males place spermatophores on the substrate or on the female genital opening (Hopkin 1997). Eggs are deposited in clumps or might be scattered on the substrate. Parthenogenesis (reproduction without males) is common among some species, and might be regulated by the presence of Wohlbachia bacteria.

Collembola inhabit a variety of specific ecological niches. There can be reproductive differences (development time, fecundity, life span, etc.) even within one species of Collembola if that species is able to inhabit a variety of habitats. Typically, every developmental stage is present in Collembola populations throughout the year (Birkemoe and Leinaas 1999). Some reproduce after every second molt (primitive species) while others have more specific and limited periods of reproduction (Brikemoe and Leinaas 1999).

Longevity:
Very few adults survive for more than 1-2 years ( Hopkins 1997). However, life history differs with each species, some having a life cycle of 23 - 27 days, other of 5 -10 months (Ashraf 1969). Species that occur in caves and extremely cold climates might live longer. Hypogastrura tullbergi, an arctic Collembola, does not even reproduce until the third year (Birkemoe & Leinaas 1999). Pseudosinella decipiens has lived as long as 67 months in a laboratory setting (Hopkin 1997). Collembola do not go through metamorphosis. They molt throughout their entire lives, with some molting up to 50 times.

Ecological Importance:
Springtails are the most abundant hexapods on earth, reaching up to 50,000/m 2 in some forest habitats. They are important food sources for beetles, spider, mites, and other carnivorous invertebrates.
Despite their abundance, Collembola are so small they add very little to the total animal biomass and respiration of the soil (Hopkin 1997). They contribute less to respiration in temperate climates (1-5%) than in arctic climates (10%) (Hopkin 1997). However, Collembola make the highest soil respiration contribution in areas of early succession (Hopkin 1997). The frass of springtails breaks down slowly and releases nutrients to plant roots over time.
Collembola are very important in conditioning detritus for microbial break down as well as in forming soil microstructure (Chahartaghi, et al 2005). Certain species (e.g. Sinella curviseta) feed on plant-parasitic fungi such as the cucumber fungus, Fusarium oxysporum. Also, plant growth can improve when Collembola feed on mycorrhizal fungi on roots and stimulate growth of the symbiont (Hopkin 1997). There are a few pest species that can cause economic damage. One of these, Sminthurus viridis, causes severe damage to leguminous crops, especially alfalfa (lucerne), in Australia (Wallace 1974) and Tasmania (Ireson 1993). S. viridis has also been introduced into New Zealand and South Africa as eggs in subterranean clover seed from Australia (Wallace 1964). S. viridis is distributed worldwide now and has become such a common pest it is known as the lucerne flea (Ireson 1993).
Two mites, Bdellodes lapidaria and Neomolgus capillatus, have been used as biological controls for S. viridis (Wallace 1974). For chemical control, carbaryl, chlorpyrifos, omethoate, and isofenphos have been found to be most effective for immediate control and for the most long term effect (Bishop, McKenzie, Barchia, & Spohr 1998). Another Collembolan pest, Onychiurus spp., has been observed causing initial damage to the roots of sugar-beet seedlings (Baker and Dunning, 1975).