With the advent of highly sensitive mass spectrometry techniques, the minute amount of various secretions produced by living animals can be studied to a level of details never attained before. In this study, we used LC-ESI-MS to analyse the injected venom of an indo-pacific piscivorous cone snail, Conus consors. While long-term follow up of several captive specimens have revealed a typical "venom fingerprint" for this species, dramatic variations were also observed. In the most extreme case, a single cone snail unexpectedly produced two very distinct venom profiles containing completely different sets of peptides with no overlap of detected masses. Surprisingly, there was no correlation between the peptides produced in the venom duct and those obtained after milking live cone snails, implying yet unknown mechanisms of selection and regulation. Our study defines the notion of intraspecimen variation and demonstrates how this phenomenon contributes to the overall venom diversity.