Mean number of tongue flicks and mean percent (lower values) tongue flicks (s.e.m.) directed at non-envenomated (NE) and envenomated (E) mice by Crotalus atrox when mice were envenomated by whole crude venom. Single-sample t-test was conducted on mean percentages where mean percent to E mice were compared with 50%, the value expected under the null hypothesis; df = 6. Because the two means are not independent, the same t value but with the opposite sign would be obtained for each mean. For raw data, see Additional file 1, Table S1. ** P < 0.01.