Investigating the Behavior of Lumbriculus

Kathy Ramsey and Kay Widmer

Overview

Lumbriculus is a small, easily cultured aquatic worm. Because of ease of maintenance and culture it is an excellent organism for classroom experimentation. The following activities enable the students to clearly view behaviors of the worms and analyze their results with a focus on observation and the adaptive value of the behaviors they observe. These activities can serve as an introduction to follow-up activities with the worms, or they can stand alone as a way of introducing student to the techniques involved in behavioral studies.

Biology Concepts

• Animal Behavior

Class time

One or two class lab periods. Addition time for pre-lab and wrap-up discussion may be needed.

Background Information

For habitat, niche, and anatomy refer to "Introduction to Lumbriculus" section.

Materials

• Worm cultures and culture containers

• Spring water

• Brown and white paper towels (torn in one-inch pieces)

• Several sheets of colored construction paper (torn in one-inch pieces)

• Light source (lamp)

• Nylon screen material cut in six-inch squares

• Frozen colored ice cubes

• Culture dishes

• Pea Gravel

• Construction gravel

• Mud

• Thermometer

Teacher Preparation

Complete background and culture information on "mudworms" as they are commonly called, can be found in the Experiments with Lumbriculus section. You will need a sufficient quantity of worms to supply containers at the work stations and to maintain a stock culture. Each container should have enough worms to be readily visible to the students.

These activities can be run simultaneously by setting them up at different stations. At the lab’s conclusion, each group should report their result to the class.

Activity 1 - Cover Section This activity is designed to determine the color of cover material preferred by Lumbriculus in a laboratory setting. The worms seek the cover of leaves and other debris in nature. Students will first test for a preference of light or dark substrate by placing worms in a container with equal numbers of one-inch square paper towels. If there is a preference for dark, the student will choose three dark colors of construction paper and test for color preference in a similar manner. Repeat for three light colors if there is a light color preference. If there is no light or dark preference, repeat the experiment using all six colors.

Activity 2-Startle Response This activity is designed to test the sensitivity of the worm’s tail to moving shadows. It is known that worms hold their tails up to or slightly above the water’s surface. This allows them to take in more oxygen and detect shadows with photoreceptors in the tail. In this activity, students are required to determine if there is a difference in the response when various degrees of shading are applied to the light. (How many respond each time and how fast do they respond?) Students start by passing a hand between the light and the worms. Note the startle response. When the worms have returned to their original position put two screens over the light and repeat making the shadow. Repeat with four screens and six screens.

Activity 3 - Temperature This activity is designed to explore the temperature preferences of the worms. The student should set up three deep dishes containing cool spring water, room temperature water, and warm spring water. Students should record the temperature in each dish. Using a pipette, the student should place an equal number of worms in each container. Activities of the worms should be observed to determine if there are differences in tail waving and response to shadows at the varying temperatures. Next, the students should add one or two colored ice cubes to the room temperature water. AS the ice cubes melt, observations should be made to note any changes in the worms behavior.

Activity 4 - Substrate This activity is designed to determine if the worms prefer a particular substrate texture. The bottom of the container should be divided into thirds using the three types of substrates: pea gravel, construction sand, and mud. Students should add thin layers of each substrate and fill the container slowly with water. The sediments should settle before the worms are added. Students should then spread the worms evenly in the water and wait until the worms have settled before counting the number of worms on or in each substrate.

Extensions

An extension of Activity 2 would be to cut several segments off the tails of a few worms and then follow the same procedures on the tail segments only as described in Activity 2.

An extension of Activity 4 would be to determine the rate of blood flow in the worm at varying temperatures over time, using a stereomicroscope. Graph the results. (Use "the Effects of Blood Flow on Lumbriculus" for procedure.)

About the Authors

Kathy Ramsey is a biology teacher at Parkview Arts and Science Magnet School in Little Rock, Arkansas. Kathy can be contacted at Parkview Arts and Science Magnet School, 2300 Barrow Road, Little Rock, AR 72204 or by e-mail at kramsey@ualred.ualr.fred.org

Kay Widmer is a biology and ecology teacher at Hopewell Valley High School in Pennington, New Jersey. Kay can be contracted a t Hopewell Valley High school, Pennington Titusville Road, Pennington, NJ 08534 or by e-mail at widmer@pluto.njcc.com

Name: Date: Period:

Investigating the Behavior of Lumbriculus

Student activity Sheet

Activity Factor Being Tested

Behavior Observed

Change in Factor Being Tested Worm Behavior Observed

(temperature, color, substrate)

1. Did the worms in your activity show any behavioral preferences?

2. How might any preferences shown be of adaptive value to the worm?

3. From looking at other students’ results, what other preferences did the worms show?

Considering he life cycle of Lumbriculus, how might these preferences have adaptive value?

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