1. Difference in Metabolic Rates in Sand
Fiddler Crabs and Crickets
By: Sydney Fletcher, Katie Baumann, and Quinn Jones

2. Question
“Which creature has a higher metabolic rate,
house crickets or sand fiddler crabs?”
Hypothesis
The fiddler crabs would have a much
higher metabolic rate, indicated by an
increase in CO2 levels

3. House Crickets
• About one inch in size
• Light brown in color
• Live about eight weeks
• Have three tarsal body segments
• From the phyla Arthropoda

4. Sand Fiddler Crabs
• Live in sandy, muddy areas
• Decapods- they have ten legs
• Have a square outer shell
• Males have one large claw that is used for
fighting other males
• From the phyla Arthropoda

5. Variables
• Dependent Variable- Change in CO2
• Independent Variable- the two different
species

6. Methods
• Roughly five grams of each species was
placed into testing bottles
• CO2 levels were measured
• Three separate six minute tests were run
for each species
• All data was recorded

7. Table and Graph
Rate of change/gram
Trials crickets Crabs
1 0.728038961 0.072568571
2 0.9547 0.02764977
3 0.028354545 -0.00004832
mean 0.570364502 0.033390007
standard deviation 0.482881871440103 0.0366471820913777
t-Test: Paired Two Sample for Means
Variable 1 Variable 2
Mean 0.570364502 0.033390007
Variance 0.233174901765496 0.0013430159552386
Observations 3 3
Pearson Correlation 0.624289775839346
Hypothesized Mean Difference 0
df 2
t Stat 2.01796576040195
P(T<=t) one-tail 0.0905401988726987
t Critical one-tail 2.91998558035373
P(T<=t) two-tail 0.181080397745397
t Critical two-tail 4.30265272974946
CO2 Levels (ppm)
Change in CO2 Levels (ppm/sec/g)
1.0000
0.7500
0.5000
0.2500
0
-0.2500
1 2 3
Trials
Crickets
Crabs

8. Results
• Mean value for crickets= 0.570
• Mean value for fiddler crabs= 0.033
• The crickets have a higher change in CO2,
therefore they had a higher metabolic rate

9. Results Regarding The Hypothesis
• The data we collected refuted our original
hypothesis
• The results suggest that the house crickets
need more energy than the fiddler crabs
because they take in more oxygen, and in
turn, release more CO2

10. Limitations We Encountered
• Our time limitation only allowed for us to
preform three test on each species
• Other teams used the animals before we
were able to use them (this might have
caused the animals to be stressed or overly
stimulated)