The dinoflagellate Gonyaulax is responsible for elaborating the toxin (saxitoxin) that causes paralytic shellfish poisoning (PSP) The name “red tide” is based on the characteristic red pigment of the Gonyaulax PSP appears in large bloom between the months of May and October and is found primarily along the eastern seaboard (although blooms have increased across the world in more recent years and may be found on either U.S coast) The animals that ingest and concentrate this toxin are primarily bivalve shellfish, including mussels, clams, oysters, and uncommonly, scallops The toxin, saxitoxin, is capable of reversibly binding neuronal sodium channels, resulting in depolarization disturbances The toxin is heat stable After ingestion of contaminated shellfish, patients quickly develop nausea and vomiting, followed by generalized paresthesias, cranial nerve disturbances, and weakness Severe intoxications may lead to cardiorespiratory failure Treatment of PSP is supportive Patients may require ventilatory support until the intoxication resolves over hours to days