Sometimes they grind their teeth when they're uncomfortable. It can be a sign of pain or discomfort. But sometimes they can do it when they're happy too. If you're scratching their chin and they grind it, they can do more like a teeth chattering thing- a tooth purr. It sounds like they're purring, but really it's their teeth. Otherwise, when they grind their teeth, they can be uncomfortable too. So it depends on the context of what's happening and if it's normal for them to purr.

They can see colors, which is one of their unique features compared to the rest of the rodent family. They can see at night, but not super well. So it's not like our night vision, but they can see a little bit at night.

They're eating all the time. They should eat hay throughout the day, and their GI systems are always working. They have to be pooping all the time because their intestines have to be going in order for them to absorb the nutrients. So constant eating, constant pooping, and constant moving are the way that their GI systems work and the way that it keeps them healthy. What goes in has to come out.

They don't. I guess sometimes their eyes can be a little bit open, but generally, they sleep with their eyes closed.

No, they shouldn't swim. That's not something that we should test out. I put mine in the bathtub with just a tiny bit of water, so they can walk in there, but I can't say I put enough in the tub to like have them try to swim. It's not one of their natural behaviors. I felt like I was torturing her because she screamed the whole time. She had some poo on her feet, so I figured I'd have her walk it off in the water, and I don't think she liked it very much.