Paralytic shellfish poisoning (PSP) is a serious illness caused by consuming shellfish contaminated with toxins produced by certain types of algae, particularly dinoflagellates. These toxins can accumulate in the tissues of shellfish, such as clams, mussels, and oysters, making them dangerous to eat. Symptoms of PSP can include tingling, numbness, and difficulty breathing, and in severe cases, it can lead to death. PSP is often monitored by health authorities to prevent outbreaks. People are advised to check local advisories before harvesting or consuming shellfish, especially during algal blooms, when toxin levels are likely to be high.