Resistances of Sympatric and Allopatric Eels to Sea Snake Venoms

Responses of four species of eels to the venoms of two species of sea snakes, a dietary generalist (Aipysurus laevis) and an eel specialist (Laticauda colubrina), were compared. All eels tested were more resistant to the specialist venom than to that of the generalist. Two muraenid eels (Gymnothorax hepaticus and G. undulatus), both sympatric with both sea snakes and probably their prey, were found to be remarkably resistant to venom. By contrast, two species of garden eels (Heteroconger hassi and Gorgasia maculata), sympatric with the snakes but unlikely to be preyed upon by them, were sensitive, as was an allopatric eel (Anguilla rostrata). Because Anguilla, an eel with good gaseous exchange through the skin, is sensitive to venom, it is unlikely that cutaneous respiration is the sole mechanism of resistance.