Did you hear the one about the elephant in a zoo who was so bored they built it a gigantic treadmill?

Or how about the octopus in an aquarium that passes its days shorting out the lights by squirting jets of water at them?

These examples — along with a recent story about a chimpanzee in a Swedish zoo who stockpiles rocks to throw at gawking visitors — may sound like fodder for late-night comics, but they are actually heartbreaking, all to real, anecdotes.

It is impossible to imagine being confined for our entire lives, as captive animals are. The very essence of freedom is being able to come and go as we please, decide when and what to eat, hang out with people we like and avoid those we don’t, choose and court our mates and decide whether or not to have children.

We punish criminals in our society by denying them these liberties. Yet animals in zoos, who have committed no crimes, are denied all of these important choices.

We assuage our guilt about keeping animals in captivity by convincing ourselves the animals don’t “know any better.”

But any living beings who are denied their freedom instinctively know they are missing something. Natural instincts don’t somehow disappear just because an animal isn’t where he or she is supposed to be. Just like us, animals want and deserve to live their lives as nature intended.

Whatever their cognitive abilities, animals will do whatever they can to alleviate the unrelenting monotony of captivity. Those fascinating octopuses, for example, never miss an opportunity to express their dissatisfaction. Staffers at a California aquarium recently walked in to find the facility flooded after an octopus pulled the plug on her tank.

Dottie, a boxfish who lives at a British aquarium, passes the time playing with a giant die, her only “companion.” Unbelievably, aquarium officials admitted that they had hoped Dottie might eventually come to see the die as a mature and friendly adult boxfish.

Some animals become so disoriented by their artificially regimented lives they engage in behaviors they would never exhibit in the wild. Jenny, the lone elephant at the Dallas Zoo, is often doped up on mood-altering drugs in order to control her aggression and self-mutilating behaviors.

Gus, a polar bear at New York’s Central Park Zoo, spent so much of his time swimming figure eights in his pool he had to be put on antidepressants.

It’s exceedingly rare for mother animals to reject their babies in the wild, yet mothers in zoos are so far removed from their wild roots that birth often leaves them bewildered and afraid. After enduring invasive and traumatic artificial insemination procedures, female elephants are frequently chained by all four legs as they give birth. It’s little wonder they can become crazed and panicky.

Freedom is more than just the ability to move about. True freedom means being able to love and play, seek pleasure, pursue interests, fulfill one’s desires and live comfortably. Freedom is self-determination. All living beings, humans and animals, want those same things.

Our freedom is so precious to us we set aside a day every year to celebrate it. So how can we justify denying animals the freedoms they hold dear?

Lisa Wathne is the senior captive exotic animal specialist for People for the Ethical Treatment of Animals.