Hunting the Mighty Tardigrade

scanning setup

Figure 1. Setup for scanning for water bears.

Ever since I was first introduced to the tardigrade (AKA water bear) on an episode of the new Cosmos series hosted by Neal deGrasse Tyson, I have been determined to find one. So for the past two weeks I have been on the hunt for them. Today, my persistence was rewarded.

Tardigrades are truly amazing invertebrates, able to survive the vacuum of space, long periods of dessication, and exposure to high dose X-rays. It is worth noting that only some individuals in a population exposed to such extreme conditions survive, not all, but that is still pretty phenomenal. Enough so that Bob Goldstein and workers at the University of North Carolina at Chapel Hill is developing protocols for studying the water bear with the aim of using it as model organism suited to the study of evo-devo and resistance to extreme environmental conditions.

The method I used to find my first tardigrade (first two actually) is described in Hunting for ‘bears’ in the backyard by Dave Walker. I also got some useful information from Mike Shaw’s site Tardigrade USA. There is little of the type of lichen (yellowish orange, fluffy and fruticose) suggested as a good place to look in my local area (Colorado Springs, CO) so I focused my attention on moss. I collected moss from the ground in a pine forest in a local woods and soaked it overnight in filtered tap water. After squeezing out the moss water into Petri dishes, I scanned the bottom of the dishes under 20x magnification with a stereo microscope using side illumination (see Figure 1). No luck after a number of tries. After reading that moss growing on rocks was more likely to harbor water bears I kept an eye out for better material.

bear moss

Figure 2. Sample of moss in which water bears were found.

Three days ago, on a trip up to Guanella pass on the way to the Mt. Bierstadt trail head (which I climbed that day with my step dad—our ninth fourteener together) I spotted plenty of moss growing on the boulders at the side of the road just outside of Georgetown, Colorado. I grabbed a few pieces and brought them back home for a soak (Figure 2). After the squeeze out, I found one after about five minutes of scanning under the stereo scope. Big fun!

Figure 3. Speencer microscope with Exo Labs iPad camera system attached.

Figure 3. Spencer microscope with Exo Labs iPad camera system attached.

Using a small pipette I transferred tardigrades to well slides and observed them with my Spencer binocular microscope, to which I had also attached an Exo Labs camera system (Figure 3). Hint: Make sure there is plenty of water in the dish before trying to collect tardigrades with a pipette, or else the pipette will cause a lot of turbulence when it enters the water, making the tardigrades difficult to zero in on.

After isolating the first tardigrade, I found another one and attempted to image it using the macro lens on the Exo Labs camera. But, the image was too grainy and it proved difficult to set up the Petri dish at a working distance to allow enough magnification of the bottom the plate. However, the Exo Labs system was quite useful for capturing both still and video images of the organisms at 40x, 100x and 450x when used in conjunction with the compound microscope.

The following video presents both the still images and motion capture video, along with a descriptive narration, of these fascination invertebrates found all over the world, and of course, in Colorado.