Bivalves are farmed in enormous quantities globally and are often presented as an ethical animal protein. But the question of whether they experience suffering is more complex than often assumed.
The bivalve welfare question sits at the edge of current scientific knowledge. The precautionary principle is less compelling here than for vertebrates or cephalopods, given the extremely limited nervous system complexity. However, scallops in particular show behaviours that suggest some degree of sensory processing beyond reflexive responses. The most prudent approach is to remain humble about the limits of our knowledge while acknowledging that bivalves are probably at the lower end of the sentience probability spectrum among farmed animals.