Sperm Suspensions:

           1. Add 2mm of sperm to 100 mL of sea water (1 drop with fertilize 5mL of egg
                suspension)
           2. The teacher may need to adjust the sperm dilution to prevent polyspermy.
           3. This will most likely be too many sperm, but this is just for demonstration purposes.
           4.  It is interesting to show students that just a little sperm can fertilize an entire beaker
               of eggs.
 
Egg Suspensions:

           1. Pour the egg suspension gathered from spawning into a 100 mL graduated cylinder.
           2. Fill to 100 mL with sea water, and let the eggs settle. Without centrifugation the eggs
               will swell. (4 mL of egs at the bottom of a 100 mL cylinder is really a 2% egg
               concentration.)
           3. Dilute the 2% eggs 1:20 (10 mL of 2% eggs into 180 mL of sea water) to a 0.1% egg
               concentration. This better for long term storage of unfertilized eggs (a few hours to
               one day without antibiotics) or development (3-5 days).
           4. Suspend the eggs in a large flask or petri dish no greater than 1 cm in depth to insure
               adequate exchange of gases.
 
Eggs can be re-concentrated to allow for easier viewing by letting them settle in a beaker or test tube and pouring off the excess sea water.
 

To Demo Fertilization:

   1. Have the students place a drop of egg suspension on a glass depression slide under their
       microscope (a less that 1% egg concentration will allow students to see individual eggs.)
   2. Let them see and focus on the eggs.
   3. Next, while the student focuses on the eggs, add a small drop of stock sperm suspension to
       the drop of eggs and add a cover slip. Quickly, let the students focus on the eggs and watch
       the fertilization membranes rise. (View under a dissecting or compound microscope.)
 
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