It is relatively simple to harvest sea urchin eggs and sperm.
To induce the release of gametes, inject 1 ml of 0.5 M KCl around the mouth of the urchin. Place the male urchin mouth down in a clean, empty Petri dish and place the female urchin mouth down over a small beaker filled with artificial sea water at 57.2 degrees Fahrenheit.
After a few minutes, the urchins will begin to release their gametes.
Tightly cover the Petri dish of sperm and place it in a bowl of ice.
After the eggs settle at the bottom of the beaker, gently pour off the artificial sea water and replace it with fresh artificial sea water of the same temperature.
The sperm will keep for up to two weeks but the eggs should be used on the same day that they were harvested.
To make fertilization easier, wash the jelly coat from the eggs. Soak them with artificial sea water until the eggs settle at the bottom, then pour off the water. Repeat this process four times. Transfer the eggs to a different beaker filled with 10 ml of artificial sea water. Allow them to settle.
Using a micropipette, transfer 50 ul of sperm to a test tube. Dilute the sperm with 5 ml of artificial sea water. Mix by gently shaking the tube. Add 0.1 ml of this diluted sperm to the beaker containing the eggs.
Use a depression slide filled with the solution of gametes to observe fertilization under a microscope.
Notice that shortly after an egg is fertilized, a fertilization envelope begins to form.
You can perform several additional experiments .
For a sperm dilution experiment, use different concentrations of sperm to fertilize the eggs. Observe the results under the microscope.
Conduct a pollution experiment: Attempt fertilization in an artificial sea environment contaminated with pollutants such as bleach and detergents.
Alter the pH of the fertilization environment with drops of hydrochloric acid.