It looks like they don't have eyes. That may be the reason why they have been around so long.

@Sticks48 Many tardigrades have long hairs on their bodies that sense the environment, like a cat’s whiskers. They also have simple eyes that notice if it’s light or dark out, but they can’t see color. Just like us, they have guts that hold and digest food, muscles for moving, and brains for thinking. Unlike us, they don’t have lungs, and instead soak up oxygen straight from water. [askabiologist.asu.edu]

These creatures just fascinate me.

@TheoryNumber3 Thanks for the information.