Xenopus skin mucus induces oral dyskinesias that promote escape from snakes.

African clawed frogs fed to American water snakes induced yawning and gaping which slowed ingestion and facilitated the frogs' escape without inducing flavor aversion. The peptide and/or indolealkylamine contents of the frog's poison glands caused the effect because frogs with purged glands did not induce these behaviors and rarely escaped. Poison gland mucus, applied orally, elicited similar oral movements. The frog's clear lubricating mucus was inactive. As several compounds in the poison glands have known neuroleptic properties, the oral behaviors may be induced by neural mechanisms reported to govern neuroleptic-induced orofacial dyskinesia in schizophrenics.