DEVELOPMENTAL ABERRATIONS ASSOCIATED WITH TWINNING IN LABORATORY-REARED SEA-URCHINS

Twinned sea urchins of Arbacia punctulata were reared in the laboratory from single first cleavage blastomeres through metamorphosis to reproductive adults. A pair of metamorphosed urchins, reared in the same container, with adequate food, typically differed in size and gross morphology. Aberrant plate variations of the normal apical system arrangement for the species were expressed by a significantly greater number of twinned urchins than controls derived from whole zygotes. The influence of early embryogenesis on the development of adult features is discussed. © 1979.