EPOW - Ecology Picture of the Week

Snow Fleas of the Soil

Snow Flea (Hypogastrura cf. nivicola), Family Hypogastruridae
Cascade Mountains, Washington, USA

Explanation:  Retrieved from a "soil excision" sample in the conifer forests of the Cascades Mountains of southern Washington state, USA, is this wonderful collection of tiny invertebrates known as springtails.  Also going by the name "snow fleas," springtails can play key roles in the ecology of the forest soil ecosystem.

But first, a quick word on the above triad of photos.  I had extracted the organisms from the soil sample using a "Berlese-Tullgren" funnel method, where you put the soil sample in a funnel with a mesh filter, placed under a strong and hot lamp.  The light and heat induces living organisms that are sensitive to losing body moister to burrow down, where they pass through the filter and drop into a sample plate below.  

My photos above are of the retrieved sample, where I used direct, pass-through lighting from below ("transmitted light microscopy") so as to highlight some internal structures of the organisms.  The top photo is at 10x magnification, the middle photo at 60x, and the bottom photo at 200x.

So, snow fleas -- springtails of this genus Hypogastrura -- live in the upper layers of soil and litter.  There, they feed on decaying plants, bacteria, lichen, and fungi.  They serve a critical function of decomposing forest vegetation litter, thereby passing nutrients on to other organisms of the soil.  They can be present in great numbers, and as such their presence and density can signal the health of a forest soil ecosystem.  

During snowfall in winter, they can appear on the top of the snow surface, feeding on algae.  This is what gave rise to their nickname "snow flea," although they strictly are not fleas (nor are they snow, for that matter, ha).  

Monitoring their presence and abundance could be an easy way to determine and monitor trends of forest ecosystem health and productivity.

And in a previous EPOW episode, we had explored the value of another species of springtail to serve as an indicator of environmental disturbance.  What important and useful organisms are these tiny denizens of the forest soil!

Acknowledgment:
     My deep appreciation to Dr. Andrew Moldenke of Oregon State University for his kind tutorship, guidance, and collaboration on the field work for this project.  I am forever grateful for that!