Contents

06 December 1991
Vol 254, Issue 5037

About The Cover

The Hawaiian sepiolid squid Euprymna scolopes uses the luminescence of bacterial symbionts in its nocturnal behavior. This ventral dissection (the squid is ˜3.5 centimeters in length) reveals the light-emitting organ as a complex, bilobed structure in the center of the mantle cavity. Normal light-organ development is initiated by specific strains of Vibrio fischeri. See page 1491. [Photograph by William Ormerod, University of Southern California]