Name: ______________ Planarian Lab

Date: _______________ Asexual/sexual reproduction


A. Introduction

The purpose of this lab is to introduce the topic of reproduction. We will look at an organism called a planarian and observe how it reproduces. The objectives of this lab are to:

        Examine your background knowledge on reproduction

        Develop new understanding of reproduction

        Compare predictions to observations



B. Pre-lab Questions

On your own, answer the questions below.


1.      What do you think asexual reproduction is?



2.      What do you think sexual reproduction is?



3.      How many parent cells do you think are needed for asexual reproduction? Sexual reproduction?




C. Class Discussion:

Please write the definition given to you by the teacher.


Asexual reproduction









Sexual reproduction






D. Group Discussion


In your groups, please answer the following questions:


1.          Name 5 organisms that reproduce asexually?



2.          What might be some advantages and disadvantages of reproducing asexually?














3.          Why might it be beneficial for plants to reproduce asexually? How might this be done? Where?










4.          What are planarians?





5.          Where do they live?





6.          What are considered their anterior and posterior ends?




E. Lab Exercise:



        Petri dish


        Spring Water (The planarian should come with bottle of spring water)

        Eye dropper or pipette

        Dissecting knife

        Graph paper



Please list 3 characteristics of the planarian without touching it. (Use full sentences)






















1.          Observe your planarian using the microscope. Sketch the planarian below. Label the anterior and posterior ends.





2.          Measure your planarian by removing some of the water from the dish and waiting for the planarian to stretch out. Measure the length of the planarian in millimeters. (Always replace the water; you can use the dish lid to transfer water to and from the planarian environment.)


Length: __________.



3.          Observe the planarian for five minutes. Does the planarian seem

active or passive? How does it move? Where in the dish does it spend most of its time? Make a current in the water with a pipette. How does the planarian react? Fill out the table below.





Worm Location


Reaction to Current









4. Pour out some of the water, so that the planarian is mostly out of the water.

When it stretches out, use a razor blade to cut it cleanly in half. Replace the water and put the lid on it. Observe the two pieces of the planarian under the microscope. ****Group #1 will cut the planarian in the middle. Group #2 will cut just the tip of its tail off. Group #3 will cut right below the eye spots.







Fill in the table with your results:



Movement (observations)

Length (mm)


Anterior End




Posterior End






F. Predicting


How long do you think that it will take the planarian (in days) to completely regenerate?




What do you think the planarian will look like after it regenerates?












G. Daily Logs

In your daily log please record your observations and length of the anterior and posterior ends.


H. Conclusion

1. Please draw below what your planarian looked like.








2. How does this compare to your picture in the Predicting section? Was it the same? What is different?






3.   What was the final length of you anterior and posterior ends? How does this compare to the initial length of the planarian in Lab Exercise question #2?





Evaluation: (The following guidelines will be used to determine your grade).


Each criterion is based on a point system from 1-5, 1 being the lowest possible score and 5 being the highest possible score.


Is the lab complete? ______

Neatness ______


Completed on time ______


Pictures were accurately

drawn and parts were labeled ______


Thoughtfulness of prediction

and conclusion ______


Total points ______