Cone snails that hunt and eat other snails are carnivores called molluscivores. Some cone snails will eat other kinds of snails, such as cowries, olive shells, turbo snails, and conch snails, while others will eat other cone snails.
In our Meet the Snails section, there are two cone snails that are mollusc-eating, Conus marmoreus
and Conus omaria. These cone snails are able to kill and swallow prey that are larger than themselves. It is documented that Conus species can swallow prey that weight up to half of their own weight. (Journal Molluscan Studies 73/2/123). Cone snails swallow their prey whole and then digest their prey in their oesophagus and stomach.
Check out Dr. Olivera's Holiday Lecture on the HHMI biointeractive website to see a video of the mollusc hunter Conus textile about to eat its mollusc prey.
The snail’s body is attached to its shell by a columellar muscle that holds onto the columella, the axis of the snail. This muscle is also responsible for allowing the snail to retract back into its shell. If this muscle is broken, the snail will lose its shell and die. It would make sense then that this muscle is always tight. It is hard to detach this muscle in a live snail, or even in a dead snail. So how can a cone snail detach this to remove its prey? It is thought that the conotoxins in the venom are able to completely relax this muscle so that the body can be pulled out from its shell. The cone snail will use its foot to hold the shell of its prey. Using a strong, steady pulling motion the body of the snail can be forced out and then swallowed whole. Complete digestion of a snail can take many hours, even days.