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
View all images in this issue.

Springtails
by Kenneth Christiansen

In contrast to their sensitivity to dry conditions, many Collembola are quite resistant to cold. Some species, such as the European "glacier flea," Isotoma saltans, are active on snow or ice at temperatures well below freezing. This species, and probably others, feed on pine pollen plant, fragments and other debris trapped on the glacier surface. Similar species are known from North American and elsewhere, including a record species found over 21,000 feet on Mount Everest. Collembola are also abundant at high latitudes, and extend closer to the poles than most terrestrial organisms. Indeed the closer one gets to the poles, the more springtails dominate the soil systems. In some arctic regions the soil is largely made up of Collembola fecal pellets. One of the simplest ecosystems known can be found in some inland areas of Antarctica, where the only macroscopic organisms are one species of lichen and one species of springtail. Some species of Collembola can thrive in high temperatures. One Hawaiian species lives primarily in volcanic vents with constant temperatures mostly between 90 degrees and 130 degrees Fahrenheit.

Most Collembola do not change strikingly in form from the first molt after hatching through their adult state. The number of setae increase. Body ratios, patterns, and pigmentation change. And of course structures associated with sex do not appear until sexual maturity. They are unusual in that many species have no fixed number of molts. They can keep molting indefinitely. At first they continue to grow with each molt, and eventually they shrink at each molt. Females continue to increase the number of eggs laid during each period between molts after sexual maturity, for a couple of molts. But then the number of eggs decrease and eventually they stop reproducing entirely but continue to molt. The world record number of molts so far is 52. Another unusual feature in a few springtails is the fact that sexual differentiation of males is, except for the family Sminthuridae, generally weak and appears only shortly before maturity. However, in some species the differences between males and females continue to increase with each molt, as long as the animals live.