Crab climbing on grate.

[aussieJJDude]

Yep, its a common belief and many do stand by it. But I've used products that contain metal, and the crabs haven't had any problems with it of illness that I can/will relate to metal.

[Rawrgeous]

Yep, its a common belief and many do stand by it. But I've used products that contain metal, and the crabs haven't had any problems with it of illness that I can/will relate to metal.

Ditto.

[Keg]

When I first got Azazul, the 40 gallon came with a screen top, so I used it. She spent hours upside down rattling around. I thought it was good she was getting so much exercise and had found some activity that she had a passion for. I mentioned it to the previous owner and she said, "I won't put the top on because of that. It's annoying."

Then I realized that Azazul was doing it to be annoying. She didn't like the top because it trapped heat in the tank and it was reaching survival threatening levels. So no more of that.

She has plenty of Cholla wood to climb on and it goes a foot and a half above the opening on the 55 gal now. But she doesn't hang around up there like she did with the screen. Probably because the higher she goes, the warmer the temperate gradient in the room gets. If climbing was fun for its own sake she'd be there. But she isn't and there's no point in being annoying without a good reason. So Azazul is very charming, and gets more and more charming if I keep the temperature low. She eats like a horse when the temperature is cool and knocks down all the snail shells I put up on the climbing trees. The exact temperature in the tank is hard to say; The digital gauge is consistent, but I suspect somewhat irrelevant. The tank temperature can vary from room temperature by over ten degrees higher or lower due to a convection current coming off the wall (from outdoors temperatures). And there is a gradient that depends on height and also proximity to the lamps. So I just set the temperature according to how happy the crab seems. She likes it much lower than the suggested temperatures for Hermit crabs.

But I digress. It's interesting that the crab stays upside down so long;
1)They don't have ears, or an associated balancing mechanism like an inner ear so that they don't really care if they're upside down or even rolling. They don't get dizzy. They balance by sensing the effect of gravity on their muscles.
2) They seem stronger proportionately than humans if they can hang that long.

And
3) I'm making an assumption here that the crab is climbing around on the grate to be annoying. That assumes they are trying to communicate and are acting intentionally.

[LadyJinglyJones]

If you find that your crab climbed more actively when the temperature was higher, its likely because a crab's metabolism increases multiplicatively with each increment of temp increase.

Though as for a metal screen lid, it probs didn't increase the temp much.