Yes, and they each have retinas made of guanine crystals! And gigas is distinctive for surrounding its eyespots with little rings of reflective cells called iridophores!
Bivalves typically display bilateral symmetry both in shell and anatomy, but there are significant departures from this theme in taxa such as scallops and oysters.
In Oysters (Crassostrea virginica), serotonin increases, and dopamine decreases the activity their cilia to regulate water's movement along their gills, and for capturing food particle.
The smallest legally harvestable clams are called countnecks or peanuts, next size up are littlenecks, then topnecks. Above that are the cherrystones, and the largest are called quahogs or chowder clams.
Although clams may not possess a brain, they have ganglia and sensory organs that allow them to respond to their environment. They can detect light, vibrations, and even chemicals in the water.
I was responding mirthfully to your declamation that you were not going to turn this into a Clam Facts Forum. You never said the rest of us shouldn't. Are you a Clam Biologist? Do you have some new Clam Facts for us?
Edit: Ooh, you are a Clam Biologist! Eee, how exciting and interesting!! Thanks for posting your blog!! And no, I'm not a poison dart frog biologist, but I think they are nifty. Tho' I am curious about all biology, mostly I focus on H. sapiens and related species.