Toxin sponges prevent poisonous animals from intoxicating themselves. This was suggested researchers from University of California, San Francisco, Stanford University and the California Academy of Sciences.
To get this conclusion, researchers have isolated batrachotoxin, an extremely potent sodium channel toxin, from Pitohui birds and golden poison frog. These species were highly sensitive to batrachotoxin. This led them to believe that they do have batrachotoxin-resistant sodium channels. Therefore, they suggested that these poisonous species depended on "sponge" proteins that absorb toxins to stop them binding to sodium channels.