Cephalopods

All cephalopods are molluscs, but not all molluscs are cephalopods. It's a classic square and rectangle situation. Cephalopods are prominently known by their tentacles, the muscular hydrostats that are their own variation of evolution from the molluscan foot, and are particularly delicious. The three most commonly eaten cephalopods are squid, octopus, and cuttlefish. Between these three general types of cephalopods there are hundreds of species, and new ones are frequently being discovered. Cephalopods are found in all of the world's oceans, and cannot tolerate freshwater, with the one sort-of-exception being the Atlantic Brief Squid, which can tolerate low-salinity brackish water. But who wants to eat Brief Squid anyway, am I right?