Biology 101-Principles of Biological Systems
(For Non-Biology Majors)

Wet Lab # 1: Pill bugs and the Scientific Method

Synopsis of today's class


                In this class you will work with animals with which you most likely are familiar - Pill bugs. You will conduct observations of these animals and design your own experiments to answer some basic questions about their behaviors. You will communicate the results of your investigation to your classmates and make some statements about the behavior of Pill bugs based on the collective knowledge acquired by the entire class.


      Objectives for this class


        At the conclusion of this class,


(1) you will have an appreciation of the process by which scientific knowledge is constructed-the scientific method       


                (2) you will have designed, carried out, and communicated the results of an experiment


 (3) you will start keeping Pill bugs as pets  J


                 (4) you will have put together the first presentation of the semester



Note: This lab exercise was adapted from Sally Kneidel’s book: Creepy Crawlies and the Scientific Method


Equipment needed for this activity.


§  petri dishes

§  filter paper, sand, soil

§  Pill bugs.




1. Using a Petri dish ands dissecting scope observe creature and. Is it an insect? How can you tell?  Do you a pill bug or a sow bug?  How can you tell





Insects were among the first invaders of land from the sea, a place in which life first evolved. All cells require water to function and keeping hydrated on land requires special features. Insects have evolved a number of physiological adaptations that protect them against dehydration. Among these adaptations are an efficient tracheal respiratory system that minimizes water loss during respiration, efficient excretory systems that minimize water loss in excretion of toxic nitrogenous waste (the function of urine), and a waxy covering that reduces water loss through the skin.


Pill bugs are crustaceans (e.g. crabs, lobsters, crayfish etc) that are mostly aquatic animals. They have moved onto land recently in evolutionary time and therefore have not evolved many of the physiological characters that aid insects to survive and flourish on land. Pill bugs do not have a waxy cuticle and therefore lose water through their skin especially in low moisture environments. They breathe through gills that must remain moist in order to function in gas exchange. Animals’ main concern is how to stay alive. Pill bugs that are poorly adapted to their land environment, so how do survive? They compensate with behavioral adaptations.


Procedure, continued


2. At this point assemble in inquiry groups and based on the preceding nuggets of knowledge and your observations predict what one such adaptive behavior may be.


3. Of course after you conduct your experiment and collect your data, you will need to find the most effective way to summarize it and communicate your findings.




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