Until now, five groups of shellfish toxins have been distinguished, namely: paralytic shellfish toxins causing paralytic shellfish poisoning (PSP); diarrheic shellfish toxins causing diarrheic shellfish poisoning (DSP); amnesic shellfish toxins causing amnesic shellfish poisoning (ASP); neurotoxic shellfish toxins causing neurotoxic shellfish poisoning (NSP); and azaspiracid shellfish toxins causing azaspiracid shellfish poisoning (AZP).