otters are not immune to paralytic shellfish poisoning, despite some popular belief that they are. however, they have the ability to manipulate their prey enough to avoid the paralytic shellfish poisoning toxins so that they do not consume lethal amounts. alaskan sea otters prey heavily on the butter clam, which has the ability to retain toxins obtained from dinoflagellate blooms. captive sea otters were fed live butter clams in a study designed to test toxin avoidance and the otters discarded the siphons and kidneys before eating the clams. most of the toxins are concentrated in these organs.