Animal Behavior with Isopods

Responses to Environmental Variables

Objectives• Observe animal behaviors relating to

environmental stimuli

• Design and conduct an animal behavior experiment

• Use Chi-Square to determine statistical significance of the data collected

Animals: Isopods

• Porcellio laevis (sow bugs) or Armadillidiumvulgare (pill bugs)

• Land-dwelling (terrestrial) crustaceans

• Related to lobsters, crabs and shrimp

What do you know about isopods?

Isopod Taxonomy

• Kingdom Animalia

• Clade Euarthropoda (arthropods)

• Subphylum Crustacea (crustaceans)

• Class Malacostraca

• Superorder Peracarida (presence of a brood pouch)

• Order Isopoda

Isopods• Prefer dark, humid environments

• Breathe with gills which must remain moist

• Females may carry up to 200 eggs in a brood pouch (located under thorax)

• Molt as they grow

Isopod Behavior

• Porcellio laevis (sow bugs) – flee or remain perfectly still when threatened

• Armadillidium vulgare (pill bugs) – curl up in tight balls for protection

Three Part Lab

• Activity A1: Initial Observation of Isopod Behavior

• Activity A2: Orientation Behavior of Isopods

• Activity A3: Designing an Experiment to Test Isopod Behavior

Animal Behaviors

• Observe two innate behaviors in isopods

• Orientation behaviors: taxis and kinesis

Behavior: Taxis

• Taxis: Turning of an animal’s body towards or away from a stimulus (directional)

• Positive taxis (towards) and negative taxis (away)

• Specific examples include phototaxis and chemotaxis

Behavior: Kinesis

• Kinesis: Random turning or movement of an animal in relation to a stimulus, usually to find “comfort zone”

• May involve a change in rate of movement

Behaviors Evolve by Natural Selection

• Some unicellular protists move towards light (positive phototaxis)

• Earthworms move away from light (negative phototaxis)

• Some bacteria move towards high concentrations of glucose (positive chemotaxis)

Activity A1: Initial Observation of Isopod Behavior

• Observe the isopods for 10 minutes in a petridish

• Undisturbed behavior

• Make notes on the isopods’ movements

–Agonistic (related to fighting: threats, displays, retreats, placation)

– Taxis and/or kinesis

Activity A2: Orientation Behavior of Isopods

• Observe isopods as they respond to humidity differences in their environment over time

Scientific Question: Do differences in humidity affect isopod behavior?

• Alternative Hypothesis (HA):

• Null Hypothesis (H0):

• Independent Variable:

• Dependent Variable:

Activity A2: Orientation Behavior of Isopods

• Clean filter paper on each side of choice chamber

• Use pipet to saturate the filter paper on one side of the chamber with water (no excess)

• Transfer 5 isopods to each side of chamber

• Count and record the number of isopods on each side of the chamber every 30 seconds for 10 minutes

• Continue to record even if the isopods stop moving

Activity A3: Designing an Experiment to Test Isopod Behavior

• Select one variable listed below to investigate

Variable Conditions

Temperature Cool, Warm

Light Light, Dark/Shade

pH Low pH (Acidic), High pH (Alkaline)

Substrate Surface Smooth vs. (Chooseone)

Choice Chamber and 10 Isopods

Before You Begin….

Complete Parts 1-5 and then check in with me:

• State the factor to be tested

• State a hypothesis for your experiment

• List the materials needed for the experiment

• List the procedure to be followed

• Describe the data that will be collected and how the results will be displayed (qualitative and quantitative)

Materials

• plastic bags

• warm water

• ice

• light source

• aluminum foil

• screens

• filter paper

• tissue paper

• wax paper

• plastic wrap

• colored paper

• cotton

• gravel

• KOH (alkaline)

• HCl (acidic)