Pill Bugs

Abstract

In this lab Armadillidium vulgar, also known as pill bugs, are tested to determine their environmental preferences. This information was determined by first making an ethogram of the observed behaviors of the pill bugs. Next, five more experiments were performed to conclude the environmental preferences of the bugs. These experiments involved testing two different environments against each other and observing the pill bugs for ten minutes to see their preference. The environments included: wet versus dry, light versus dark, low pH versus high pH, low pH versus neutral pH, and high pH versus neutral pH. These experiments concluded that the pill bugs prefer a wet and dark environment; however the other experiments were inconclusive what kind of pH the pill bugs prefer. In conclusion, it can be seen from this experiment that Armadillidium vulgare prefer to be environments that are darker and moister.

Introduction

Animal behavior can tell scientists about the various responses an organism has to different stimuli. In order to study animal behavior the scientist must clearly define what the behavior is. A good way to track an animal’s behavior is to categorize them on an ethogram. An ethogram is a good tool in understanding how an organism survives, mates, and reproduces. After a scientist has correctly described each behavior, he or she can ask four different questions about the behaviors: causation, development, evolution, and function. Each of these four ideas has a specific question it is asking about a behavior. Causation is trying to find out what the basis is for the animal performing the certain behavior. Development asks how the certain behavior changes during the organism’s lifetime. Scientists can also find the differences between innate and learned behaviors. Evolution asks how the behavior has changed through the history of the organism. Lastly, function determines how the behavior benefits the organism. Another concept in animal behavior study is the simple movements. There are two different types of simple movements that animals can produce. One is known as kinesis, which is an increase in the rate of activity due to a response to a stimulus. The other movement is known as taxis. Taxis are the movement away or toward a stimulus, such as light or gravity (Bonner et al., 2007.). Also, orientation is defined as a process by which animals position themselves with respect to spatial features of their environments (“Isopod, Pill bugвЂ¦Ð²Ð‚Ñœ).

In this experiment I work with a group of isopods known as Armadillidium vulgare, more commonly known as pill bugs. During the lab, I find out the behavioral preferences of these bugs in different experimental habitats. I test the bugs in five different environments. In general, isopods are land dwelling crustaceans commonly known as sowbugs or pillbugs. These bugs are related to lobsters, crabs, and shrimp. Even though both types of isopods look alike, sow bugs are unlike from pillbugs. Pillbugs will curl into a ball when threatened while sow bugs will try to flee. The appearance of the isopods affects the type of environment that the bugs prefer. Isopods have three body parts that include the head, the thorax, and the abdomen. They also have one of antennae, straightforward eyes, seven pairs of legs, seven disconnected segments on the thorax, and paired appendages at end of abdomen. The color of the bug can vary any where from dark gray to white without any patterns. Most isopods have gills in order to breathe, for that reason they usually live in areas with high humidity. These characteristics enable the bugs to survive in their environment (“Isopoda”).

In this lab, there are six different experiments to study the animal behavior of the Armadillidium vulgare. The first part involves categorizing the behavior of the pill bugs by making an ethogram. For the next five experiments, several different environments are tested to determine which environment the bugs prefer. For the first experiment, the pill bugs are tested for their preference of a wet environment versus a dry environment. I predict the bugs will prefer the wet environment because “terrestrial isopods are poorly adapted, morphologically and physiologically, for life in dry habitats” (Huang). In the second experiment, the pill bugs are tested to see if they prefer a light or dark environment. I predict that the bugs will prefer a light environment because the light can help them see and scavenge for food. In the third experiment, the bugs are tested for their preference of an acidic environment versus a basic environment, using HCl and NaOH. I predict that the bugs will prefer the basic side. This is because the basic side has a more neutral pH than the acidic side and won’t be has harmful to the bugs. For experiment number four, the bugs are tested in an acidic environment versus a non-acidic environment. I predict that the pill bugs will pick the non-acidic environment because the acid has such a low pH that it could be harmful to the bugs. In the last experiment, the bugs are tested for their preference for a basic to a non-basic environment. I predict the bugs will prefer the non-basic environment because it is a more neutral environment and probably won’t cause much harm to the bugs.

Methods

For the first part of the experiment, I observed the pill bugs in a semi-natural environment. I made careful observations of the bugs. I noted things like if the bugs were moving or resting, etc. After I was done making the observations, I made an ethogram of the behaviors. I followed the exact procedures of making an ethogram as described in the L113 Lab Manual on page F-2.

For the second experiment, I obtained ten pill bugs from a bucket where the pill bugs were kept. I kept the pill bugs in a plastic container in between each experiment. I obtained a tray, in which each side would serve as a different environment. I tested the bugs’ preferences for a wet environment versus a dry environment. For this experiment I placed a wet paper towel on one end of the tray, while the other side of the tray remained dry. I placed ten pill bugs in the center of both environments. I observed the pill bugs for ten minutes and recorded how many pill bugs were on each side of the tray. I then removed the pill bugs and replaced them in the plastic container. I cleaned up the tray, so it was ready for the next experiment.

For the next experiment, I tested the bugs’ preferences for a lighted area versus a darker area. For this experiment, I took a lamp and placed it over only one half of the tray, so only half the tray was lit up. I used black construction paper to cover the other