Defensive chemicals such as the ink secretion of this marine gastropod mollusk—the sea hares Aplysia californica—are released following attacks from predators for protection. One might expect these secretions to be complex mixtures of products, given that they must work against a diversity of predators. In their Full Paper on page 1597 ff., C. D. Derby et al. describe some of the chemical complexity of the ink of sea hares attributable to the enzyme “escapin”. Escapin is an L-amino acid oxidase that oxidatively deaminates its major substrate, L-lysine, to produce an equilibrium mixture of the molecules shown in this image. Photograph from Genny Anderson (Santa Barbara City College).