Glacier Collembola (springtails)

and Their Habitats on North Cascade Glaciers 

Paula Hartzell, Biology Project Leader, Clark University, Department of Biology, Worcester MA 01610 

Collembola are commonly referred to as 'springtails' or 'snowfleas.'   Collembola are a very ancient order, sometimes included under Insecta, and sometimes placed in their own order because of some very unique characteristics -- such as their furculum or 'spring' used for jumping -- are not present in any of the insects.  Collembola occur in virtually every kind of environment:  they are found in soil, fresh water, salt water, snow, ice, and about anywhere else you'd care (or not care) to think about.  Most species of Collembola found on glaciers of the North Cascades are also found off glaciers, on snowpack, on pools of water, or in duff in the forest.  At least one kind of Collembola (here referred to as the "Behemoth" (Agrenia n.sp.)) appears to occur only on the glaciers of our region -- not off glaciers, and not in other regions.  

 Collembola are so small that they are often missed during glacier travel.  The black Collembola (Isotoma n. sp.) in the photo at the top of this page is about 0.5mm long.  The smaller, lighter one may be a juvenile of the same species.  (Species identification was possible only with the help of Ken Christiansen of Grinnell College.)  The most common species of springtails on North Cascade glaciers is the white-antennaed kind (Isotoma (Myopia) n. sp.), shown in the photo below, at right.  It is similar to the species alaskana found in Alaska.  These wierd guys have two eye facets right at the base of their antennaes, serving unknown function.  They are only about 0.1mm long, and you probably won't see them when you are on your feet.  When sitting down for a break, though, look around; they were found on every glacier in the North Cascades included in our survey. 

The big springtail in the left photo (above, with a black sprintail) is one of my beloved behemoths.  This springtail is about 1 mm long, about the size of a dog flea, so you can actually see them hopping around on the glaciers without much problem.  They do not appear to go off-glacier, and they occur at much lower densities than any of the other North  Cascades springtails.  You usually only see one or two at a time, and then only if you're lucky.  I have only found them on Mount Baker's glaciers, but I'm guessing they probably occur on glaciers north of there as well.  (Let me know if you see them!)  Other species in this genus are found in the arctic and subarctic, although none have been found on glaciers before.  These unique characteristics, and the behemoth's limited distribution, make it a candidate for scientific and conservation focus.

Just how many snow fleas are there on these glaciers?  Snowflea and ice worm maximum densities recorded during the 2002 field season are shown on the table below.  (The actual mean density is much higher, as we could only count in one place at a time, so missed the 'peak' at most stations.)  On Honeycomb Glacier (south side of Glacier Peak), for example, the recorded mean density was ~400 snow fleas per square meter.   With an area of  4.1 square kilometers, this represents over 1.6 BILLION snow fleas on this glacier alone!   Gosh, I'm glad they don't bite people.

Because there are usually several species of Collembola on each glacier, and because the distribution of these species vary, it is likely that springtails will be the focus of ecological studies on glaciers in the future.

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