Shellfish are very poisonous to humans. There poisoning is caused by a group of toxins elaborated by plank tonic algae which the shellfish feed on. The toxins are accumulated and sometimes metabolized by the shellfish. The 20 toxins responsible for paralytic s (PSP) are all derivatives of saxitoxin. Diarrheic (DSP) is presumably caused by a group of high molecular weight polyethers, including okadaic acid, the dinophysis toxins, the pectenotoxins, and yessotoxin. Neurotoxic (NSP) is the result of exposure to a group of polyethers called brev ....