Antipredator tactics of amphibious sea-snakes (Serpentes, Laticaudidae)

Because the antipredator behavior that an animal displays depends upon the context in which it encounters the predator, apparent interspecific differences in antipredator tactics may result from ecological rather than behavioral differences among taxa. We approached 127 free-ranging laticaudid sea-snakes on small islands in Noumea Lagoon, New Caledonia, prodded the animals midbody, and recorded their responses. One species (Laticauda colubrina) usually remained immobile (relying on crypsis) whereas another (L. laticaudata) generally fled. However, multivariate analysis shows that the two species actually responded in very similar ways to any given stimulus; the species differed overall because colubrina was generally encountered on land during the day whereas laticaudata was more often encountered in the ocean at night. Thus, apparent interspecific differences in antipredator responses were secondary consequences of interspecific differences in the times and places that predators were encountered. Snakes were more likely to flee rather than remain immobile when rapid locomotion was possible (i.e. juveniles rather than adults; in water rather than on land) and pursuit by a predator was difficult (i.e. at night rather than during the day). These patterns suggest that snakes adjust their antipredator tactics in ways that maximize the chances of surviving the encounter, although the remarkable docility of these highly venomous snakes remains puzzling.