Morphology and genetics of sea urchin development

Abstract

Sea urchins can be raised from egg to egg in the laboratory. With proper food, the larvae can be grown to maturity in about 3 weeks. When mature larvae are exposed to the proper chemical cues metamorphosis occurs. Over the next 5 days the small urchins develop internal organs and then begin to feed. Sexual maturity can be reached in as little as 4.5 months. By then the urchin is about a centimeter in diameter.Several different approaches to the study of developmental genetics are covered. These include: (i) hybrids between the sand dollars Dendraster and Encope, in which both crosses produce offspring that have predominantly paternal characteristics; (ii) a preliminary description of two mutants, one which produces abnormally shaped blastula that may lead to a significant number of exogastrulae, and another that produces a large number of four-part symmetrical urchins; (iii) urchins produced by parthenogenetic activation and from reaggregated larval cells. © 1975 by the American Society of Zoologists.