It is a generalist predator, but primarily preys on large bivalve mollusc species. It pulls their wings apart with all five arms and then everts its stomach into the shell. It can dig clams out of the seabed on occasion. It can be selective or opportunistic depending on availability of prey. It sometimes also preys on gastropods, crabs, barnacles, ascidians, sea squirts and algae. It has also been seen preying on itself during periods of low food abundance. It will also eat dead fish and fish waste.