Tales from the Crypt #31

Two men aboard a cargo ship are bored until they get the idea to build a rat trap and ask the Captain to have a barrel built with a platform in the middle of it and a run off down the center. They fill it with water and attach a teeter to the rim with some food attached to the end of it so that when a rat attempts to get it, it falls into the water and swims to the platform. When another rat approaches and falls into the drink, they bet on which rat will survive the bloody struggle for the platform. Later, when their ship sinks, two find out that humans are not much different from rats!