Variation of traits and habitat use in three species of sea kraits in Taiwan

Three sympatric species of sea kraits (Laticauda spp.) were found to have different degrees of aquatic tendencies at Orchid Island (=Lanyu), Taiwan. All species move to coastal areas at night. Generally, Laticauda semifasciata remain submerged in sea water, L. laticaudata emerge onto land, but remain not far from the water's edge, while L. colubrina tend to move farther inland away from the water. Attributes of morphology and physiology can influence the performance and survival of snakes differently in aquatic or terrestrial habitats, so we hypothesize that some attributes of structure and function will vary among these three sympatric species of sea kraits. We measured parameters of the body shape, vascular lung, saccular lung and hematocrit of sea kraits to investigate possible morphological correlates of their physiology. The most aquatic species, L. semifasciata, had a significantly more laterally flattened body form, larger saccular lung volume and higher hematocrit than the other two species, whereas only few differences were found between the two less aquatic species. L. laticaudata had a significantly higher hematocrit than L. colubrina.