As small as it may be, the dinoflagellate Dinophysis makes itself known to humans in an unpleasant way. Shellfish consume a toxic substance excreted by dinophysis when it blooms and people eat shellfish. When concentrations are too high, shellfish are dangerous to eat. The animal itself suffers little from the harmful algae, however shellfish-eating people can suffer from intestinal and stomach disturbances. Fortunately, after a couple of days of nausea, the only remaining effect is that it will probably be a long time before the victim eats shellfish again. Since the 1970s, this toxic alga has been found occasionally in shellfish harvested from the Oosterschelde and the Wadden Sea.