Amnesic Shellfish Poisoning (ASP) is caused by domoic acid, a toxin produced by marine phytoplankton known as Pseudo-nitzschia. When shellfish filter out large amounts of domoic acid and Pseudo-nitzschia, they can become contaminated with enough toxin to cause ASP. Humans then get ASP by eating those contaminated shellfish. (including clams, mussels, oysters, and crabs). Symptoms of ASP develop within 48 hours and include vomiting, nausea, and diarrhea. Symptoms for more severe cases include headaches, dizziness, confusion, and permanent short-term memory loss. In rare cases, ASP can lead to coma and death. There is no antidote for domoic acid, but patients with ASP should be taken to a hospital for supportive medical care until the toxin passes through their system.