Marine toad (Bufo marinus) - Many people are surprised to learn that the impressive marine, or giant toad, is native to South Texas. It is a tropical species that reaches its northern limit here. Like all toads, it has skin toxins to dissuade predators, but this species is particularly toxic and can kill dogs that try to eat it. The toxin, called bufotoxin, is concentrated in the parotid glands, the large oval glands behind the eyes.