Sea Urchins as Lab Animals for Reproductive and Developmental Biology

Sea urchins have been used for more than a century in cell and developmental biology research. The sea urchin is a gamete production powerhouse. Male and female sea urchins are easily induced to shed massive numbers of eggs or sperm. The eggs are mature at release and are fertilized externally simply by mixing egg and sperm. The resulting embryos are optically transparent and develop synchronously in nothing more than sea water. High quality genome and transcriptome data are available for several urchin species, and the eggs and embryos are amenable to rapid-repetitive microinjection of mRNAs, proteins and dyes. These animals are also favorites in the classroom, and are easily used for live demonstration of fertilization and early development. The major discoveries in sea urchins have dramatically advanced knowledge of sperm-and-egg interactions, egg activation mechanisms, cell cycle control, genetic networks of development, and protection of the embryo and germline. This article summarizes current knowledge of sea urchin reproduction and its current uses in reproductive and developmental research.