Experiment on Minimal Segment Size Regeneration of Lumbriculus variegatus

Elke Bergholz

Overview

Lumbriculus variegatus is an aquatic annelid. Cultures of this worm require little maintainance which makes it an ideal organism for class room experimentations. The following experiment was based on the worms' ability to reproduce asexually by fragmentation. The experiment allows students to observe regeneration of tailless and headless worm segments into complete individuals. Data of a completed experiment are included as well as a student activity sheet.

Biological Concepts

• Asexual reproduction • Regeneration of worm segments

• General cell regeneration • Environmental adaptations

Class Time

Students would benefit greatly if an initial class time of 45 minutes for observation of

Lumbriculus could be provided. An additional 45 to 60 minutes would be needed to set up

the experiment in which students will remove sections of the worm. During the following 5

to 7 days, students need 5 to 10 minutes each day for observations and recording. A

maximum of 45 minutes are nesessary for the final segment.

Background Information

Lumbriculus variegatus , an aquatic oligochaete, has developed a reproductive strategy that

is well suited for populations that live in the very shallow margins of ponds and are

subjected to hazards of rapid environmental change and vulnerability to predation.

Segments can develop into complete individuals by regenerating new head and tail

segments (C.D.Drewes and R.O. Brinkhurst, 1989). In this experiment, students can

answer the question of what the minimal number of segments is from which Lumbriculus

is capable of regenerating into a complete individual.

The students may need to know the anatomy of the earthworm (Lumbricus terrrestris )

which is also an oligochaete and related to the aquatic oligochaete Lumbriculus.

variegatus. A dissection of the earthworm might help them to be prepared for fragmenting

the aquatic Lumbriculus variegatus. Students need to know about asexual reproduction by

fragmentation. It might be helpful to the student discussing the deliberate fragmentation of

the worm before the actual dissection. It is important to point out to the students

that deliberate fragmentation will help the worm to reproduce.

Results of a past experiment showed that Lumbriculus variegatus is able to regenerate

from small fragments without head nor tail. The minimum number of segments of these

fragments was 3. Complete organisms were observed after 6 days. The worms were

further observed for an additional 5 days. All new head region regenerated 7 - 9 new

segments whereas the new tail regions regenerated 20 -55 segments depending on the

original number of segments of the fragment.

Materials

• a culture of Lumbriculus variegatus, now available through Carolina Biological

• scalpels

• spring water

• dissecting microscope

• cell - well culture container

• forceps

Teacher Preparation

Caring for the aquatic Lumbriculus is a simple procedure. For details see introduction to "Experiments with Lumbriculus". Once the culture is established, as much time is needed as it takes to prepare the materials. Though water change is not essential, it is advisable to have spring water provided during the duration of the experiment in case of need.

Cell culture chambers are available through COSTAR - Cooperation, Cambridge, MA 02140, 1-800-492-1110.

Resources

Berrill, NJ., Regeneration and budding in worms, Biol. Rev., 27 (1952) 401-438.

Brinkhurst, R.O. and Jamieson, B.G.M., aquatic Oligochaeta of the World, University of Toronto Press, Toronto, 1971, pp. 104-143.

Drewes, C.D. and R.O. Brinkhurst . Giant nerve fibers rapid escape reflexes in newly hatched aquatic oligochaetes, Lumbriculus variegatus (Family Lumbriculidae). Invertebrate Reproduction and Development, 17:2 (1990) 91-95.

Website of C.D.Drewes: http://www.molebio.iastate.edu/htm/drewes.html

About the Authors

Elke Bergholz, biology teacher at the United Nations International School, 24-50 FDR Drive, New York, N.Y. 10034, (212) 684 7400.

NAME:___________________ DATE: _________ PERIOD: ________

How many segments does it take?

Minimal Segment Regeneration of Lumbriculus

Introduction:

The aquatic worm Lumbriculus has the capacity of asexual reproduction trough fragmentation.

This experiment will explore the regeneration ability of Lumbriculus . We will find out how many segments (neither with head nor tail) are required to regenerate to a complete individual.

Materials:

- 10 -15 Lumbriculus

- scalpel

- dissecting scope

- spring water

- well culture apparatus

- forceps

- petri dish

Procedure:

1. place a single worm into a petri dish with spring water

2. gently cut a worm fragment from the middle region of the worm consisting of one (1) segment

(it is important that you chose your segments from the middle region)

3. place the worm fragment into a labeled well containing spring water

4. repeat step 2 and 3 removing two, three, four, five, six, .... segments from the middle regions

of the worms: each without head nor tail

5. cover the well chambers and place in the dark (water can be changed but is not essential)

6. observe each fragment every day and record your observations:

count the number of regenerated segments of both the head and tail region

7. maintain regenerated worms in an aerated new culture for additional experiments

8. summarize your results and discuss the following:

Discussion:

1. Discuss the importance of asexual reproduction of Lumbriculus v..

2. Explain the advantage of the capacity of segment regeneration for organisms such as this worm.

3. Find similar examples of cell regeneration in other organisms and compare.

4. Design an experiment which could provide you with information on environmental impacts on

the fragment regeneration of Lumbriculus. v..

5. Discuss the ecological importance of Lumbriculus v..

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