If it were left to my pacman frog, I think he would do nothing other than bury himself.
Sometimes I find when he buries himself for a lengthy time, he'll inflate to gigantic proportions. Part of this is him just blowing himself up with air, but over time he seems to absorb lots of water from the media because lots of that volume appears to be pee.
Bathtime is when I scoop him out with a tablespoon (he'll still fit in a spoon) and introduce him to a warm water bath. Within a few minutes, usually, he'll pee so enormously that he deflates while he does it.
So I guess the bladder is a way to store water when they are buried.
I'm glad he isn't just absorbing water during bathtime and peeing it all out in his burrow hole. He's doing it the other way.
I had a whole month where this fellow would eat every day. And now, according to his majesty Cranwelli McNugget, we eat when we want, every other day or so.
His next meal is going to be the most gigantic cricket I can find. I think he is ready.