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The Effect of Light on Crayfish

Researched by Bethany E.



The purpose of this experiment was to determine if Crayfish are attracted to light or repelled by light.

I became interested in this idea when I had Crayfish for a class pet in fourth grade, and didnít know weather to leave the lights on around them or to leave them in a dark area.

The information gained from this experiment it will help people who raise or sell Crayfish to then know how much light they should have shining on their Crayfish.




My hypothesis is that the majority of the Crayfish will move toward the darkness, and reject the bright light.

I base my hypothesis on books that I have read, on information that I have found on the Internet, and on observations that I have had in my classroom.




The constants in this study were: 
The same amount of Crayfish in each aquarium 
The same type of Crayfish 
The same number of Crayfish 
The same amount of water 
The same amount of rocks 
The same amount of Crayfish in each area depending on the trial 
The same amount of time in between each trial.

The manipulated variable was light and no light.

The responding variable was the amount of Crayfish that responded to the light and the amount of Crayfish that responded to the darkness.

To measure the responding variable I will count the amount of Crayfish that are in each area, light and dark. 





Northern Crayfish
1 Aquarium 12 cm. deep, 20.25long, and 10.5 cm. Wide

2 bags

Rocks 2cm. Deep

3cm. deep



Foam divider 30.48 cm. high and 26.67 cm. Long




 1. Collect materials 
 2. Take an (51cm.) aquarium and measure it into two parts, each being (10.125cm.). 
 3. Mark the dividing line on the top of the aquarium with a pen. 
 4. Get a foam divider that is30.48cm.high by 26.67cm.long, cut an opening in the foam divider 8cm wide and 6cm tall. 
 5. Divide the two aquarium halves with the foam divider. 
 6. Cover the bottom of each area with rock, 2cm deep. 
 7. Cover the bottom of each area with water 3cm.deep. 
 8. Cover the top of the left area with thick, black paper. 
 9. Cover the outside of both areas with thick, black paper. 
10.Get a 60-watt light bulb and put it into a reading light. 
11.Place the 60 watt reading light 75cm.above the bottom of the right side of the aquarium. 
12.Turn the reading light on to the lowest setting. 
13.Place all six of the crayfish into the right side. 
14.Observe the crayfish for 30 min. 
15.Record the number of crayfish in each area at 5min., 10min., 15min., 20min., 25min., and 30min. 
16.Do setup 15 five different times. 
17.Place all twelve crayfish in dark side. 
18. Repeat steps 11,12, 14, and 15 five times. 
19.Make a graph to see how many crayfish are on each side at each time.




The results were that the majority of the Crayfish ended in the Dark area, regardless of where they were placed in the beginning of the experiment. 
My results indicate that my hypothesis should be excepted.  The majority of the Crayfish did go to the dark area. 




My hypothesis was that the majority of the crayfish would be repelled by light, and choose to be in the dark area. 
The results indicate that this hypothesis should be accepted, more Crayfish did choose to be in the dark area. 
Because of the results of this experiment, I wonder if the light had of been closer if more of the crayfish would have gone to the dark area, or gone to the dark area faster.If I were to conduct this project again I would have more trials, I would move the light closer to the Crayfish, and I would run more practice trials. 





Would you like to have bigger and healthier Crayfish as a pet or to eat?  Thatís possible if you have your Crayfish in the right light.  I think that this is the reason that you should read my report. The effect of light on Crayfish is my controlling idea. 
Anything that gives off light to the human eye is called a light source.  Light effects all living things.  Light sources that are not produced by people are called natural light.  Light is made up of waves similar to sound waves these waves travel through an invisible substance called air.  Different kinds of atoms produce different kinds of spectrums. 
Color in light 
When light is separated into its component colors it is called phenomenon dispersion.  White light when looked at through a prism you can see is made up of the colors, red, orange, yellow, green, blue, indigo, and violet.  This is the spectrum of light.  Color is made by the way length of light, that is the distance between the crest of one light wave and the crest of the next. 

Voltage and Electricity 
You can turn energy into electricity witch produces light.  By the way of compression, 240 volts and a current of 1 ampere flow through a 100-Watt light bulb. 

Different species of Crayfish 
One type of Crayfish is the European Crayfish.    The European Crayfish takes between 2 through 3 years to reach their full maturity, but this kind of Crayfish may live to be 20 years of age.  Some of the bigger types of Crayfish do considerable damage to the riverbanks that they burrow into. Some species of Crayfish crawl around the surrounding them at nighttime, and then they return to there burrows, when they are done looking for food. Their burrows are made in damp soil.  Some Crayfish even extend there burrowing.

Crayfish habitat 
Crayfish have to have water to live, but depending on the type of crayfish the amount of water differs.  Crayfish need a lot of calcium so they are usually found in high calcium areas, like rivers and streams or tempter regions.  Fresh water crayfish are more adaptable to live in fresh water areas.  Crayfish live in fresh water areas like river and or temperature climates.  Crayfish usually burrow into the riverbanks of streams or ponds.  Crayfish need an aquarium or a plastic tub with a layer of clean gravel on the bottom.  Some kinds of crayfish do well in very shallow water that almost covers their body.  Other types of crayfish need deeper water and a filter for their tank.  If you collect your own crayfish pay careful attention to the water level where you find them and try to duplicate it as close as possible at home.  Most crayfish do best in clean, well-Oxy generated water, so change the water daily if you donít have a filter in your tank. Tap water is usually fine to use in the crayfishís aquarium.  Put a few rocks on the bottom of the tub so the crayfish can climb out of the water when they want to.  Rock piles or clean flowerpots will provide good burrowing places for the crayfish.  If there is more than crayfish, and more than one burrowing place in one tank watch out for fighting.  Crayfish will eat bits of raw fish, meat, dog or cat food, or aquatic plants.  In the wild Crayfish eat live or decaying plants and animals.  When feeding crayfish you should put their food right in front of them, in five minutes if the crayfish have not started to eat the food you should remove the food and try again later.  In the winter crayfish like to burrow into the banks of the near by streams the greater likely hood of the water freezing the deeper the crayfish tend to burrow.


Agasstz, Louis. Animals with Shells. United States: Denver Conetecit, 1996. pp. 60-61 
ìCrayfish,î Encyclopedia of the Animal World. 1982. vol. 6. pp. 492-493 
Carter, Josephl, Goodman, Howard P., Hunter, Donny D., Schelske, Leroy J. Life Science. Lexington, Massachusetts, 1971. pp.140-145 
Dixon, Robert T. Physical Science: A Dynamic Approach. New Jersey: Prentice-Hall, 1986. pp. 170-198 
Doris, Ellen. ìCrayfish,î Animals With Shells. 1996. vol. 6. pp. 60-61 
Engelburt, Phillis. ìLight,î U.L.X. Science Fact Finder. 1998. vol. 2. pp. 351 
Engelburt, Phillis. ìLight,î U.L.X. Science Fact Finder. 1998. vol. 3. pp. 491-492 
Fetzer, Scott. ìCrayfish,î World Book Encyclopedia. 1995. vol. 4/ci-cz  
ìLight,îWorld Bookís Young Scientist. 1993. vol. 2. pp.  8-11, 24-25, 49, 52-53, 60-61, 64  
Microsoft Encarta 96 Encyclopedia. 1996 



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