Would you recognize an esox lucius if you saw one? Commonly called the Northern Pike, it is a 25-40 pound freshwater game fish. If you observe it in an aquarium, you realize quickly that this animal is the consummate carnivore. Its predatory style is to suspend itself very still in the water until a potential target gets close. Then the pike snatches it and devours it in the blink of an eye. It can literally empty out a fish tank in minutes.
But what happens if the environment is altered and obstacles are added? Researchers experimented with just that by lowering a glass barrier into the aquarium separating the pike on one side from food fish on the other. When the pike goes after a nearby minnow, it runs into the invisible divider. And after a while, the pike stops trying.
But this gets even more interesting. The observers next…
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