Final answer:
Tetrodotoxin is lethal because it blocks sodium channels in nerve cells, leading to paralysis and potentially respiratory failure and death.
Step-by-step explanation:
The ingestion of tetrodotoxin can cause death because it is a potent neurotoxin that affects the nervous system. It works by blocking sodium channels in nerve cells, preventing the normal transmission of nerve signals. This blockage leads to paralysis, including paralysis of the muscles needed for breathing, which can result in respiratory failure and death if medical intervention is not provided promptly. Similar to tetrodotoxin, other toxins like those from dinoflagellates causing red tides or from cyanobacteria can pose serious health risks by interfering with nerve function or damaging internal organs like the liver.