Sea hares' chemical alarm signal

If you are soft, devoid of tooth and claw, slow, and tasty to predators in your environs, chemical defenses are your best card. Indeed, when attacked, the sea hare Aplysia californica squirts out defensive cocktails from glands on its back. For several years, Charles Derby and Cynthia Kicklighter of Georgia State University and their colleagues have been teasing apart the chemistry and biology of these secretions. Last year, they reported that certain free amino acids in the secretions act like food decoys, causing lobsters to attend to the secretions instead of the hares (C&EN, April 4, 2005, page 14). On April 27 in Sarasota, Fla., at the annual meeting of the Association for Chemoreception Sciences, the researchers reported the identities of several other components, including the nucleosides uridine and cytidine, that carry alarm signals to nearby sea hares. When exposed to these in the lab, and presumably in the wild by brethren under attack, sea hares in the vicinity take to the hills, sometimes "galloping" away with inchworm motions, Derby notes.