What happens in a tide pool that is not stirred by wave action? A gradient is set up where the highest oxygen concentration is in the top centimeter of the water surface. The farther you go down the lower the oxygen concentration. Oxygen use in sea urchins does not begin until AFTER fertilization [sperm use some oxygen to get to the egg, but the egg itself is "dormant"]

What we need is a way to simulate different depths. We can use test tubes and other containers with different heights of seawater. The longer lengths can be done by making a long "test tubes" from a piece of 1 cm wide glass tubing. Use a wax covered cork for the bottoms.

TUBE #	DEPTH in CM
1	1 - control
2	5
3	10
4	20
5	50
6	Negative Control Add 1 cm of mineral oil to 1 cm of seawater

 

1. In a small test tube add enough eggs for the entire experiment.
2. Add diluted sperm
3. Quickly add a few drops of the fertilized eggs to each test tube above.
4. Allow the embryos to settle and remain undisturbed.
5. The next day remove the embryos and score for development.