Answer: Birds

When selecting a pet for your microgravity space base, we would advise against bringing a bird along for your deep space adventures. Although space agencies have launched all manner of creatures into space: monkeys, dogs, turtles, spiders, and yes, even birds, your feathered friend will be quite poor health-wise for life in the vacuum of space.

It’s not that birds drop dead the moment they leave the comfort of Earth’s atmosphere, it’s that they slowly waste away when they’re taken beyond the reach of Earth’s strong gravitational pull. Unlike human beings, the esophagi of the vast majority of birds is not muscular enough to contract and draw food into their stomachs in the absence of a strong gravity field like that found on Earth. Humans have throat muscles developed enough that we can eat and drink while standing on our heads (directly countering the pull of gravity in the process). Birds, on the other hand, rely almost entirely on gravity to move their food from their mouths to their stomachs (the stereotypical pelican-bobbing-its-head-straight-up movement is a practical one, the bird is lining up its esophagus so the fish slide straight down as quickly as possible).

If you brought a bird with you into space, not only would it have a terrible time moving around (they find flying in microgravity to be terribly disorienting and are rather ineffective at it), but you’d be forced to hand feed it with a feeding tube or syringe of some sort lest the poor thing starve to death in short order.