Little critters with not so little preferences!

The Pacific Spirit Park is home to a vast amount of trees and other organisms.

The Pacific Spirit Park is home to a vast amount of trees and other organisms.

This week for BIOL 326, we ventured a bit farther from the water, but the water (rain that is) followed us. The location of our exploration? Pacific Spirit Park, right on the edge of our UBC campus. The vast area of big tall trees shielded us against the sprinkle of rain as we explored a bit deeper than most would in this park; we were on the hunt…for terrestrial isopods!

What are terrestrial isopods you may wonder? They’re more commonly known as Roly-Polies, the little critters you might find in the corner when you clean out your garage on a courageous day. These little critters seem to be scattered around the forest, our question is: Do they have a preference in their environment? We will find out, by comparing their abundance above and below logs, and also simulating environmental factors to test what they may prefer.

The journey started out in Pacific Spirit Park where groups of two were formed, given zip lock bags for collection and measuring tape. The goal was to collect some numbers on how many Roly-Polies we can find on top and below decaying logs in the forest. As we observed the logs and flipped them over the tape was useful in noting how long and thick each log is. Once the collection process was over, we congregated back in the lab and compiled all our precious cargo together.

The Roly-Polies were alive and well in the large empty tank that we placed them in. It was then for the next part of the journey, to find out what these little critters prefer as their habitat? The factors we tested were temperature, light intensity and humidity. In other words, do these isopods like to be in a warmer or cooler area? Do they like bright or dark places? Do they like to live in moist areas or dry ones?

To test these, we have set up some experiments that have opposing choices, and the little guys were then given two minutes to make a choice. The set up was simple; we had petri dishes with dark/ light sides, as well as petri dishes with moist/ dry sides.

These petri dishes were used to test for the terrestrial isopods preference in light intensity. (A similar one was used for moisture level)

These petri dishes were used to test for the terrestrial isopods preference in light intensity. (A similar one was used for moisture level)

These guys are ready to participate in our study!

These guys are ready to participate in our study!

Lastly we place a tin foil pan on top of two zip lock bags with cool and hot water to test the temperature.

You can see the isopods moving about in these tin containers that were used to test their preference in temperature.

The isopods would be moving about in these tin containers that were used to test their preference in temperature.

Once the two minutes was up the side they had chosen was noted as their preference.

So what did they prefer?! I’m not going to reveal that just yet. We had over 20 little isopods for each experiment and placed them each in one container, we never put more than one though, because that might cause some fighting to happen, and our data would go down the drain! For each isopod we only used him or her for one trial and returned him to another tank that contained all those who have participated. Finally, after all our data collection, we compiled our numbers for some statistical tests. The results? [Drum roll please] These little guys preferred cool temperatures, that are moist and dark! I guess that makes perfect sense since most of these terrestrial isopods were found hidden under the comfort of the logs!

For an up close and personal look at a close cousin of the creatures we worked with, check this out:

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