Volume 39, Number 1,
October 1992:
Springtails

Text-only version

ABOUT THIS ISSUE
- about KSN
- about the author

IN THIS ISSUE
- part 1
- part 2
- part 3
- part 4
- part 5
- part 6
- part 7
- part 8
- part 9
- part 10

SLIDESHOW
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Springtails
by Kenneth Christiansen

The heads of Collembola are always oval and they have four antenna segments. In specialized forms these may be greatly sub-divided as can be seen in the member of the family Sminthuridae illustrated in Figure 7A. They are usually equipped with sensory structures which can be very complex as can be seen in Figure 7B-D. Primitive Collembola have eight separate small eyes on each side of the head which have a characteristic distribution shown in Figure 8 but these are often reduced or absent. In front of this, in many groups of Collembola, there is an organ unknown function called the post antennal organ. This structure can be simple but is often very complex (Figure 9).

Collembola consume a wide variety of foods from vegetation to nematode worms although most favor fungi, spores and decaying vegetable material. This diet is associated in most Collembola with the presence of complex chewing surfaces or molar plates on the mandibles (which can handle resistant material such as plant tissues) and short complex maxillae seen in Figure 10A. However, Collembola display an enormous variety of different mouthparts ranging from simple piercing-sucking structures (seen in Figure 10B) to elaborate mouthparts (as seen in 10C). The simple piercing-sucking structures are probably associated with feeding on the juices of fungi or other liquid foods. Some of the complex mouthparts are associated with feeding on other tiny animals such as rotifers. However, we have no idea what most of the complex mouthparts are specialized for.

The digestive tracts of springtails are very simple straight tubes; however, some genera of the family Neanuridae have giant salivary gland chromosomes similar to those seen in Drosophila and some other flies. A few Collembola have simple tracheae, but most lack any internal respiratory structures. All have a simple tubular dorsal heart.

As might be suspected from their favored diets, most Collembola are reducers, and live in litter, decaying wood, or soil, or under dead bark, stones or litter on the soil surface, where they play an important role in breaking down dead plant materials and controlling the bacteria and fungi. Many eat green plants, and these are particularly important in tropical regions. A few, such as Proisotoma grandiceps (Figure 11) are carnivores although most of such species can also feed upon dead and decaying animal and/or plant materials. Collembola generally have short generation times, with some reproducing in as little as three weeks after hatching. This, combined with their abundance in many habitats, makes them favorite foods of many small animals ranging from mites to beetles. Some forms such as Dacetine ants, are specialized for feeding on them. In many ways you can think of Collembola as filling the same roles in the small, anthropod-dominated, animal world that mice fill in the larger vertebrate-dominated, animal world.