Early Embryonic Development in the Sea Urchin, Strongylocentrotus purpuratus

Students: Katelin Nicaragua, Sarah Maffei

Faculty Mentor: Lisa Hua

Biology

College of Science, Technology, and Business

The purple sea urchin has been used as a specimen for developmental biology for several decades. The size of the egg and the sperm make them ideal for fertilization and embryonic development observations. Sea urchins are deuterostomes, meaning their mouth forms second during embryonic development. This is similar to human development, allowing us to observe and compare their development to early human development. The lab was designed to examine the early development of the sea urchin embryo over a period of 2 to 4 days. The overall goal of this experiment was to observe the embryonic development from fertilization through to the pluteus stage of development. Sea urchin sperm and eggs were collected from living specimens and allowed to combine for fertilization. Over the next 48 hours, the fertilized embryonic cultures were kept in an incubator and allowed to develop further. Observations and images were collected at the 24-hour and 48-hour time points. In addition to the culture created in our lab, a culture that had already been fertilized 48 hours prior was provided. This allowed a comparison of two specimens at different time points of development. Pluteus was not observed, and the furthest developmental stage observed was early prism. Most of the embryos died before the end of the experiment.