Brine Shrimp LD50 Toxicity Lab
Brine Shrimp are marine crustaceans, also commonly known as “sea monkeys”. Brine shrimp
eggs can remain in total stasis for two years while in dry oxygen-free conditions (called
cryptobiosis). Eggs hatch after being placed in salt water for a few hours.
The Lethal Dose 50 (LD50) is a test that is used to find out what concentration of a particular
substance will kill 50% of a population.
In this lab, you will pick a substance that you think will kill the brine shrimp. You will test this
substance to find the LD50.
Hypothesis:
Materials:
Toxic agent
Salt Water
Live brine shrimp
10 mL graduated cylinder
Pipette
5 Test tubes
Procedure:
1.
Fill in the chart below:
Independent Variable (IV)
Constants (C)
Dependent Variable (DV)
2. Setting up serial dilution:
a.
b.
c.
d.
e.
f.
Label 5 test tubes: #1, #2, #3, #4, #5
Add 9 mL water and 1 mL of your substance into test tube #1.
Add 9 mL water and 1 mL from test tube #1 into test tube #2.
Add 9mL water and 1 mL from test tube #2 into test tube #3.
Add 9mL water and 1 mL from test tube #3 into test tube #4
Add 10 mL water into test tube #5. This is your control
3. Add 10 brine shrimp to each test tube
4. Allow experiment to sit overnight
5. Count remaining brine shrimp and record your results.
Data:
Solution
Concentration
Number of dead brine shrimp
#1
#2
#3
#4
#5
Control
Graph:
Conclusions:
1. What is the LD 50 of your substance on brine shrimp?
2. Identify two experimental errors.
3. Do you think your results are valid? Why or why not?
4. Ask other students in the class and find out which substance had the worst LD 50 levels.
What does this tell you about that substance? Will that information change what you eat or how
you live?
5.Are there any ethical issues in using animals for testing LD 50 levels? If so, where do you draw
the line?
6.What information is gained through LD50 testing? In your opinion, is the information we get
from these tests worth the deaths of the organisms tested?