Prey selectivity is of vital importance in an organism’s ecology, because choosing the right prey can provide proper nutrition and prolonged survival. The common octopus (Octopus vulgaris), as the other cephalopod mollusks, is a voracious opportunistic predator that displays a wide range of prey diversity. Thus, it not a surprise to see this species appointed as a vector of harmful algal bloom (HAB) toxins several years ago. It accumulates considerably high levels of both domoic acid (DA; responsible for amnesic shellfish poisoning) and paralytic shellfish toxins (PSTs) and, concomitantly, pass them onto higher levels of the coastal marine food webs. DA and PSTs are neurotoxins that block the electrical impulses in the brain, gravely impacting the nervous system. In the present study we investigated, for the first time, the behavioural responses (e.g. attack latency times, retention performances) of O. vulgaris to contaminated (with domoic acid) and non-contaminated bivalves, in order to assess whether these molluscs show taste aversion to tainted diet.