1 2 3 4 5 6

		Materials: male and female Lytechinus variegates 100 mL beakers sterile syringes and needles petri dishes with covers artificial salt water (ASW) graduated cylinder glass Pasteur pipets glass depression slides ice bucket aluminum foil 0.5M KCl 14°C incubator 37°C incubator thermometer light microspcope digital camera Procedure: 1.Obtain gametes of sea urchins; store egg in a gently stirred suspension at 22°C, washing several times with artificial sea water (ASW) 2. Collect sperm from sea urchin and dilute one drop into 10 ml beaker containing ASW. 3. Prepare three baths of ASW at 14°C, 22°C (control), and 37° using a water bath or incubator. 4. Fertilize all the eggs with the diluted sperm in a 100 ml beaker. 5. Once fertilization envelope has developed, note time. 6. Transfer fertilized eggs and 30 ml of ASW into three glass dishes according to appropriate temperature. 7. Dilute with 30 ml of ASW at appropriate temperature (14°C, 22°C, and 38°C) 8. Cover each glass dish and place into incubator maintaining temperature. 9. Monitor the progress of development by taking a small sample and placing it on a depression slide to be viewed under a light microscope. 10. When 90% or more of the eggs have completed cytokinesis, note the time after fertilization and take still photographs. 11. Allow the fertilized embryos to develop for 24 hours. 12. After 24 hours, transfer 1 drop of each of the three samples onto depression slides. 13. Observe the sample under the light microscope. Take still photographs and compare embryonic development. 14. 48 hours after fertilization, repeat steps 12 and 13.