Materials Included In Kit

Additional Materials Required

Prelab Preparation

Isopod Culture

1. Use a large glass or plastic container with a lid (at least one gallon) as the culture container. Cut small holes in the lid for air.
2. Fill the container ONE-HALF full with compost or potting soil.
3. Add enough water to moisten the soil.
4. Place organic matter, such as leaf litter, dried grass or sawdust, on the surface of the soil.
5. Gently place the isopods into the culture.
6. Add a slice of raw potato every few days for food. Remove the potato before mold begins to grow.
7. Keep the culture at room temperature, occasionally checking the moisture level and the amount of organic material.

Safety Precautions

Acetic acid solution and sodium bicarbonate solutions are skin and eye irritants. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory. Follow all normal safely precautions. Please consult current Safety Data Sheets for additional safety, handling and disposal information. 

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Acetic acid solution may be disposed of according to Flinn Suggested Disposal Method #24a. Sodium bicarbonate solution may be disposed of according to Flinn Suggested Disposal Method #26b. Isopods may be disposed of according to Flinn Biological Waste Disposal Method Type IV.

Lab Hints

• Enough materials are provided in this kit for 8 groups of students. All parts of this laboratory activity can reasonably be completed in two 50-minute class periods. The students should read the Background section and the entire Procedure before coming to lab, and the data compilation and calculations can be completed after the lab.
• If the lab session is longer than 50 minutes, extend the observation time to 10 minutes or complete multiple trials.
• In the student-designed activity, students should test either warm or cold temperature versus room temperature, either a weak acid or a weak base versus neutral. Other choices may include wavelength of light (colored cellophane, Flinn Nos. FB0596–FB0598), surface texture (sandpaper, Flinn No. S0165), type of food (potato, carrot) and type of organic matter (wood chips, cedar chips).
• Acetic acid solution, 0.1 M has a pH of 2.9.
• Sodium bicarbonate solution, 0.1 M has a pH of 8.
• Ants, termites, ladybugs or other local insects may be used instead of isopods.
• Isopods can be purchased from Flinn Scientific, Inc. (Flinn No. LM1217) or trapped in most wooded or garden areas. Cut a deep hole into a potato. Place the potato into the woods or garden area and cover with leaves. After a few days, check the potato. Gently transfer any isopods into a culture container.
• An old leaky aquarium may be used as an isopod culture container. Cover the aquarium loosely with aluminum foil if a glass or screen cover is unavailable. A five-gallon bucket with lid will also work. Drill holes in the lid to provide air.

Sample Data

Activity 1

Answers to Questions

Activity 1

1. How do the isopods move?

   Move in random directions or along the outer edge of the container.

2. Describe the pattern of leg movement.

   Isopods move their legs randomly, several on each side may be moving at different stages at the same time.

3. Describe the reaction of the isopod to being touched.

   Pillbugs will curl into a ball with the head inside. Sowbugs will turn and move away from the touch.

Activity 2

1. Draw three graphs on graph paper showing the number of isopods in each environment tested. Determine and label the independent variable and dependent variable.
   1. Independent Variable.

      Time

   2. Dependent Variable.

      Number of Isopods

2. Based on the graphical analysis, what type of environment do isopods prefer?

   Isopods prefer a dark, moist environment because they lack the waxy cuticle found on many organisms with exoskeletons and therefore, desiccate easily. In addition, isopods lose moisture from their pleopods, making respiration (gas exchange) difficult.

3. What types of behaviors were observed when the isopods were placed in different environments?

   Both taxis and kinesis are observed. Isopods use negative phototaxis to avoid light and positive hydrokinesis to locate moisture. In a slightly dry environment the isopods pile on top of each other to conserve moisture.

4. Imagine that ten isopods were disturbed when the rock they were under was overturned. Describe, in detail, how the disrupted isopods are likely to react, based on your experimental observations.

   At first their movements will be slow; they will then turn and quickly move in many directions (in straight lines) as they move toward a dark location.

Student-Designed Experiment
Student answers will vary. In general, isopods prefer a neutral environment to either an acidic or a basic environment, a smooth versus a rough surface, and room temperature to either warm or cold.

References

Biology: Lab Manual; College Entrance Examination Board: 2001.

Introduction

Ethology is the study of animal behavior. Behavior is everything an animal does and how it does it. Many behaviors are responses to sensory input such as sight, sound, smell, touch and taste. Reactions to a sensory input may be an innate (genetic inherited) response, a learned response or a response that has both innate and learned components.
Objectives
After doing this laboratory, you should be able to:

• Describe some aspects of animal behavior, such as orientation behavior, agonistic behavior, dominance display or mating behavior.
• Understand the adaptiveness of the behaviors.

Concepts

• Behavior
• Kinesis
• Ethology
• Taxis

Background

An innate response or behavior is inherited and involves the genetic sequence of the organism. An innate response will be the same for all the organisms within a species regardless of the environment, including the lack of a “normal” upbringing. A learned response is a response that is modified based on specific experiences of the organism. A learned response will vary directly upon the life experiences of each individual organism. For example, a male Drosophila is able to create a mating song with its wings, even if it was reared in isolation. Therefore, the mating song in Drosophila is an innate behavior. In contrast, a sparrow raised in isolation will never be able to correctly produce its mating song because the song is a learned behavior.

Orientation behaviors are innate moving behaviors that put the animal in a favorable environment. Stimuli that may cause orientation behaviors include chemicals, water current, electricity, gravity, light, moisture, sound, temperature and touch. There are two main types of orientation behaviors—taxis and kinesis. Movements directly toward a stimulus are called positive taxes (singular = taxis) while movements directly away from a stimulus are called negative taxes. If a taxis response is exhibited to a specific stimulus; it is described by using the term -taxis as a suffix along with the appropriate prefix referring to the stimulus (see Table 1). Thus, the term Hydrotaxis, for example, describes an orientation response to water. The same prefixes are also used with the suffix -kinesis to describe a kinetic response. Kinesis is a change in the amount of movement and turning. Kinesis may be either toward (positive) or away from (negative) the stimulus, but the overall motion occurs via general, random movements. If an organism responds to bright light by moving away in a direct line, that is phototaxis. Kinesis occurs when an animal responds to bright light by random movements in all directions away from the light. The organism continues moving in various directions away from the light until it encounters a dark area (negative photokinesis).

Agonistic behavior is exhibited when animals from the same species respond to each other by aggressive or submissive responses (fighting or fleeing). Agonistic behaviors are complex behaviors, often with both innate and learned components. Usually, an aggressive agonistic behavior is simply a display that makes the organism look big or threatening. True fighting generally occurs only during mating season. A dog raising its fur and baring its teeth or rolling onto its back is displaying agonistic behaviors.

Isopods (also known as pillbugs, sowbugs, roly-polies, or woodlice) are members of the phylum Arthropoda, class Crustacea (see Figure 1). They live on land, usually in dark, moist areas, such as under rocks, in leaf litter or just under the surface of the soil. They have an exoskeleton, two eyes, antennae, seven pairs of jointed legs and most use gills called pleopods for respiration. They feed on decaying material, algae, moss and bark. Isopods are ectotherms—they regulate their temperature by moving to warmer or colder areas as needed. The average life span of isopods is about two years and they shed their exoskeleton to grow approximately 12 times during their lifetime. Isopods are classified or divided into two families. Isopods that roll up when poked are pillbugs or roly-polies (family Armadillididae), rolling-up behavior is call conglobulating. Isopods that do not roll up are called sowbugs and belong to the Porcellionidae and Oniscidae families.

Experiment Overview

The general movements of isopods are observed in Activity 1. In Activity 2, isopods are given a choice of environments. Data are acquired as to their preference. In Activity 3, a student-designed experiment is created, conducted and revised.

Materials

Safety Precautions

Although most materials in this lab activity are nonhazardous, follow normal safety precautions. Wash hands thoroughly with soap and water before leaving the laboratory. Weak acids and bases are irritating to the skin and eyes. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron.

Procedure

Activity 1. Isopod Observation
Remember that you are working with living organisms. Treat them with care and respect.

1. Place a piece of filter paper in the bottom of the Petri dish.
2. Use the graduated pipet to transfer approximately 2 mL of deionized water to the filter paper.
3. Use a spoon to gently remove an isopod from the classroom culture and place the isopod into the Petri dish.
4. Use a hand lens to observe the isopod’s movements for two minutes. Use descriptive terms to answer the first two questions on the Isopod Worksheet.
5. Use the brush to gently brush the isopod. Describe the reaction observed in Question 3 on the Isopod Worksheet. Activity 2.

Isopod Behavior
Remember that you are working with living organisms. Treat them with care and respect.

1. Using a spoon, gently collect 20 isopods and place them into the wet filter paper lined Petri dish.
2. Fold the pieces of 15-cm filter paper in half and cut 1-mm off of each folded edge (see Figure 2).
   {10802_Procedure_Figure_2}
3. Create a “choice chamber” by placing half-circles of filter paper onto opposite sides of the plastic container (see Figure 3).
   {10802_Procedure_Figure_3}
4. Use a graduated pipet to wet one half-circle of filter paper with approximately 1.5 mL of deionized water.
5. Use the spoon to gently place 10 isopods onto each half circle of filter paper (see Figure 3).
6. Count and record how many isopods are on each half circle of filter paper every 30 seconds for 7 minutes. Record the data in Table 1 on the Isopod Worksheet. Continue to record the number even if all of the isopods move to one side or stop moving.
7. Return the isopods to the Petri dish.
8. Use the graduated pipet to wet the dry half circle of filter paper with approximately 1.5 mL of deionized water.
9. Create a shaded area in the choice chamber by cutting and taping black construction paper to half of the top, sides and bottom of the container.
10. Repeat steps 5–7 this time testing whether the isopods prefer the dark or light side of the choice chamber.
11. Remove the moist filter paper from the shaded area of the choice chamber.
12. Place a dry half-circle of filter paper in the shaded area of the choice chamber.
13. Repeat steps 5–7 this time testing whether the isopods prefer the dark/dry or the light/wet environment.

Activity 3. Student-Designed Isopod Behavior
Remember that you are working with living organisms. Treat them with care and respect.

1. Select one of the following variable factors to test—temperature (either warm or cold) or pH (either weak acid or weak base).
2. Develop a hypothesis concerning the isopods’ response to the variable.
3. Design an experiment to test the hypothesis. Remember to control all variables except the independent and dependent variables.
4. Complete the Student-Designed Experiment Worksheet.
5. Trade experiments with another group as assigned by the teacher.
6. Conduct the experiment as written, making notes regarding missing information and comments about well-written areas.
7. Write a conclusion based on the experimental results.
8. Return the experiment and results to the group that designed it.
9. Evaluate the results and answer Questions 8 and 9 on the Student-Designed Experiment Worksheet.
10. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

10802_Student1.pdf