As far as I know, all reported cases of paralytic shellfish poisoning (PSP) have involved bivalve molluscs. Gastropods generally do not become infected, nor do Cephalopods (squid, octopus), Crustaceans (lobsters, crabs, shrimp) or finfishes. This is because bivalves are filter feeders, passing large volumes of water through their bodies, and straining out any suspended particles. Such particles can include the organisms that produce saxitoxin, primarily dinoflagellates of the genus Gonyaulax and a few other associated forms. These organisms are always present in sea water in small numbers, and normally cause no problems. But occasionally, for reasons not well understood, they undergo a rapid and massive increase in number, a phenomenon known as a "bloom" (the "red tide" being the best known example). During a bloom, dinoflagellates may be present in concentrations of many thousands of individuals per cubic centimeter of seawater. A bivalve may pass thousands of cc's of water per day through its feeding mechanism, thereby concentrating millions of dinoflagellates in its visceral mass. Gastropods are not usually a threat because they are not filter feeders, so they do not tend to concentrate the organisms. There could be some theoretical danger from Gaspropods which feed on bivalves. However, most of the gastropods that are commonly used as human food are not carnivores; and, the viscera of gastropods, unlike that of bivalves, is not usually consumed. The economic impact of a major PSP outbreak is compounded because people who read in the paper that "shellfish" are infected and dangerous, stop purchasing not only bivalves, but also lobsters, crabs, shrimp, squid, gastropods, and in some cases even finfish. (It's a great time to purchase lobsters, which are usually expensive. The seafood stores drop the prices drastically in an effort to get rid of them.) A friend told me he had passed up the escargot at a fancy buffet he attended. I pointed out that escargot are land snails which could not possibly be infected with a marine organism. But many people just react, rather than thinking it out. Many folks will not even buy canned clams or mussels during a local red tide outbreak, even though these were imported from another country. Of course, all of this is not an absolute guarantee that all Gastropods are safe to eat at all times. They could be toxic due to some cause other than PSP. Paul M.