What did Eugenie Clark discover?

In 1974, ichthyologist Eugenie Clark noticed that the delicate Moses Sole (Pardachirus marmoratus) was easy to catch and appeared to secrete a milky, astringent substance from the base of its dorsal and anal fin spines. Suspecting that the little fish was protected by a toxin of some kind, Clark collected several specimens for study. She found that the Moses Sole did indeed secrete a toxin she named 'pardaxin', which caused red blood cells to rupture and - most intriguingly - to repelled sharks. Tests by Clark in the laboratory and open sea revealed that at least four species of sharks were repelled by pardaxin for 10 hours or longer.