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

This genus, which is one of many living primarily in the small spaces between soil particles, shows another characteristic of Collembola - the relationship between body form and habitat. This form belongs to a family primarily adapted to this habitat, the family Onychiuridae. All have lost eyes, furcula and pigment and have developed short antennae with elaborate antennal sensory structures (Figure 17A). Very elaborate post antennal organs as can be seen in the genus Onychiurus shown in the same figure. In spite of the lack of furcula, these forms are not without defense. The small openings or pseudopores shown by the arrow are scattered over the body and head. These structures are openings through which the animals can voluntarily release small quantities of their blood which is repellent, or in some cases even poisonous, to predators. It is amusing to watch an ant which has seized one of these animals drop it and try vigorously for a long while to wipe off its mouthparts. Short antennae, reduced or absent furcula, lack of eyes and pigment and complex sensory structures are characteristics of a wide array of genera which have independently evolved adaptations for this habitat.

In striking contrast to this set of characteristics, those species adapted to living above the ground, particularly those living on vegetation, tend to have bright colors, clear patterns, strongly developed furculas, and well-developed eyes and antennae. The members of the families Entomobryidae and Sminthuridae, seen in the bottom two illustrations on the cover, show this type of appearance. Many species are only found in the tree tops both in temperate areas and, more commonly, in the tropics. In species living in trees in tropical rain forests this body from reaches an extreme such as shown in Campylothorax (Figure 18). These forms have remarkable jumping abilities.

Many springtails living on water surfaces, such as Sminthurides aqauticus, are similar in some respects to the forms living in vegetation (Figure 14B) but have a furcula adapted to jumping on water. Look closely at the end of the furcula and you can see the end piece of mucro is broadened like a beaver's tail. They also have feet specially adapted for running over water surfaces. They are very common along the margins of lakes, ponds, streams and in marshes. They are an important food source for aquatic insects and young fish.