As someone who has raised lobsters from larval stages they are very savage. When they are growing to become juveniles we have to put them in a vortex tumbler so that there is enough current that they cannot easily move and grab another puerulus else they will eat their sibling alive. After they get to a juvenile stage they are heavy enough to resist the current in the tumbler so we have to separate them into their own little lobster condo or they will cannibalize their siblings if we put them together. Crustaceans don't really give a fuck about anything but eating and growing bigger. The Bar Harbor Oceanarium has a good description of how this is done