This is the new home of Sea Urchin Embryology on the web. Welcome!

NOTE: The Stanford site is no longer active, but this new site has all of the same content. Please use the "Search" function below to find your page, and then update your links.

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How to Use This Site

The Core Lab takes about a week. The other labs (Primary Labs) extend the sea urchin experience over a longer more rigorous time frame (roughly 2 weeks+). If you have trouble getting and keeping sea urchins, you are probably better off just doing the Core Lab and maybe the Sperm Experiments lab.

See Experiments and Sperm Experiments, as well as Extended Research for other ideas that could be extended into longer term experiments.

  • Core Lab – Suggested for first lab experience
  • Gametes – Looks at the gametes of the sea urchin and relates them to our own gametes in terms of size and characteristics. Detailed instructions on spawning animals, collecting and storing gametes for future work. Includes sources for sea urchins
  • Fertilization – Sea urchin sperm are added to sea urchin eggs and the early steps of development are observed and discussed
  • Development – Latter stages of development are observed, from 2 cell to pluteus
  • Experiments – Environmental effects of temperature, light, pH, oxygen and toxins are looked at in relation to fertilization and development of the sea urchin
  • Sperm Experiments – Sea urchin sperm keep very easily in a refrigerator. This allows students to do multiple experiments over several days
  • Push Lab – is a set of guided experiments, based on the above ideas. [greater details and directions presented]. Because these labs are "cookbooked", they do not promote inquiry or critical thinking as much as the two experiments sections above

These are lessons meant to augment the Primary Labs or your own lessons. Your students may need some, all or none of these lessons. You may have better ways to teach these ideas and skills.

  • Pretest – Helps to assess prior knowledge
  • The Microscope – Introduction to the parts of and use of the microscope
  • Size Under The Microscope – How to determine the size of an object under a student microscope
  • Mixing The Gene Pool – Why the mixing of the gene pool in sexual reproduction is an advantage
  • Brooders vs. Spawners – Humans are "brooders" in that we have few young, which we take care of. Sea urchins are "spawners" in that they have millions of young with no parental care. So why study sea urchins?
  • Simple Dilution – Understanding dilution is an essential skill in biology. This lesson starts with an understanding of a simple linear dilution
  • Simple Dilution 2 – This lesson adds the element of experimentation in beginning to learn about serial dilutions
  • Sperm Dilution – Proper sperm dilution will help students in doing the Experiments lab and provides further understanding of serial dilutions
  • Drawing Lab – An often neglected scientific tool. What is important to record? How much detail is needed?

These are ideas that go beyond the one period classroom experience. Some could be appropriate for special interest students, others for science fair projects, etc. Each web page shows a new skill or method and suggestions for new investigations (listed in order of increasing difficulty).

  • Shaking – simulating wave action on young embryos
  • Ultraviolet Light Effects – UV causes damage to genetic and protein material in the eggs and sperm. How much does it take and what is affected?
  • Modified Seawater Formulations – What are the effects of varying formulas on fertilization and development? What happens when the magnesium is left out? Calcium? Sodium?
  • Osmotic vs. Ionic – Is it the ions in the seawater or the osmotic pressure that is important for fertilization and normal development?
  • Artificial Activation – Shown are several ways to "activate" the egg without a sperm. Are males needed at all?
  • Carnoy's Fixative – This fixative is used to preserve detail for later examination of embryos. Fixatives work by selective extraction and preservation. What can you see in the fixed developing embryo you could not see in the live ones?
  • Isolating the Mitotic Apparatus – Illustrates mechanisms for removing the plasma membrane and other cell components to enhance viewing of microtubules, chromosomes and centrosomes in the dividing cell.
  • Gamete Storage – Whereas we can keep cow and sheep gametes and embryos for years, at best we can keep sea urchin gametes for only a few weeks. But even this is an improvement over the past, where urchin eggs essentially had to be fertilized when fresh
Also see our sister site – VirtualUrchin
For questions or comments, feel free to email us.
Students collecting sperm