Objectives:

• Observe various aspects of a terrestrial isopod
• conduct experiments examining the responses of isopods to various environmental factors
• design and conduct an investigation of animal behavior

Isopod Handling and Rearing

Raise isopods in a clear shoebox or similar, the bottom should be covered with soil or sand and kept moist (use a mister). An old piece of bark, and leaf litter covering the soil. Isopods can be fed carrots, raw pototoes or apples (alternately fish flakes can be used as food). Moldy food or soil should be removed. Females can carry up to 200 eggs in a brood pouch underneath her abdomen and will remain in the pouch for about three weeks - they look the same as adults, only smaller.

Larger isopods can be handled and observed easily with your hand, by picking them up with your fingers or gently scooping them up with a spoon. They are fast walkers and can withstand short drops. Immature isopods are more fragile than adults.

**Isopods are also called sowbugs and pillbugs.

Background Information

Terrestrial ispods are land dwelling crustaceans, commonly known as sowbugs or pillbugs (or rollypollys). They are related to lobsters, crabs, and shrimp and terrestrial isopods breath with gills. While they look similar, sow bugs are different from pill bugs. Pill bugs will curl into a ball when threatened whereas sow bugs will attempt to flee. Since your isopods are caught from the wild, make sure you are using the same type for your experiments.

Ethology is the study of animal behavior. Many behaviors involve movement of the animal within its environment. In this exercise, you will investigate some innate (instincts) behaviors of isopods.

Orientation is a process by which animals position themselves with respect to spatial features of their environments. Taxis involves the turning of an animal's body relative to a stimulus - either toward or away. Kinesis is a random movement of an animal in relation to a stimulus, like cockroaches scattering when the light is turned on.

Consider the following example: A researcher places a dead rotting mouse in the center of a test area and adds a carrion beetle (an insect that eats dead animals) somewhere on the surface. The beetle crawls forward for three seconds, turns and crawls in a different direction for three seconds, and so on. The researcher concludes that the beeetle is moving randomly in relation to the dead mouse. Continued observation reveals that the beetle crawls faster (and covers more ground) when it happens to turn in the direction of the dead mouse. In addition, the beetle crawls more slowly (and covers less ground) when it happens to crawl away from the mouse. In this way, the beetle's random movements will eventually bring it to the dead mouse. It is important to take in details such as time spent crawling in one direction or another when observing the movements of the animals.

Assignment:

This lab will appear as a journal entry in your sketchbook. I want it to sound like a naturalist keeping a log of their observations and research. I will give extra points for creativity. I want you to make sure you answer all the lab questions in your journal entry but I want you to do it in an organic and natural way so it does not sound like you are answering questions.

1) What type of organism will you study in this lab?

2) List two organisms it’s related to.

3) Define crustacean. (It is not in this pre-lab, you will have to look it up and write a definition in your own words.)

4) Define ethology.

5) Define taxis

6) Define kinesis.

Isopod Observations

In the first part of this exercise, you will observe pillbugs and record what you see.

Analysis (include in lab journal entry. The analysis can be written as notes and does not have to follow paragraph form.)

• How do the pillbugs seem to sense their environment?
• Are they all the same species?
• Can you tell the difference in males and females?
• How many eyes do they have?
• How many legs
• Do they exhibit dominance behaviors?
• How do they respire?
• What are some stimuli they seem to respond to?

Scientific Sketching

When you make a sketch of a pillbug, don't just draw an oval with a few squiggly legs - you are expected to do a scientific illustration similar to the sketch of an earthworm below.