Marine toxins are chemicals and bacteria that can contaminate certain types of seafood. Eating the seafood may result in foodborne illness. The seafood may look, smell, and taste normal. There are several types of marine toxins, and they all cause different symptoms. Marine toxins are poisons of biologic origin that may be used as chemical weapons. These toxins are produced by a variety of organisms ranging from small microbes to fish and snails. These toxins are not infectious. Exposure to the toxins either by invenomation, ingestion, or inhalation may lead to a death through paralysis of cardiac or respiratory muscles.Several marine toxins discussed here are further classified as neurotoxins. These toxins can interfere with the transmission of the nerve impulse by blocking specific ion channels. The neurotoxins vary in mechanism of action. The concentration of the exposure to the toxin is not indicative of its effects. Several toxins can cause seizures or paralysis in nanomolar concentrations, others may cause gastrointestinal upset or blindness in much larger concentrations.