HCA: Hermit Crab Association

There's still a lot of fear of metal in general, and rust, as it concerns our hermit crabs.It is my theory that iron is not dangerous to crabs, rusted or not. Rust doesn't seem to actually be dangerous to anything, it just looks ugly. Rust is nothing more than the compound iron oxide. If you lick rusty nails all day for years you might eventually get iron poisoning, but you can also get water poisoning from drinking too much in a short period of time.----------The burdon of proof at this point seems to be the other way around. As far as I can find, there is simply no evidence that rust is bad for crustaceans, or humans.http://en.wikipedia.org/wiki/Rusthttp:/ ... _oxideIt's not listed as toxic or a pesticide in the pesticide database:http://www.pesticideinfo.org/Detail_Che ... ----Entire underwater ecosystems are created on the rusted out hulls of old ships. The use of rusted hulls of sunken ships for artificial reefs on the ocean floor is common knowledge:http://en.wikipedia.org/wiki/Artificial ... ------Rust (Iron oxide) is actually a mineral-based pigment for red lipstick, approved by the FDA up to certain levels. This is one of those rare cases where synthetic iron oxide is actually better than natural iron oxide, because iron oxide will absorb lead, mercury, and arsenic from its natural surroundings, but synthetic iron oxide has no such toxic compounds. But we don't have to worry about that, since there isn't any lead, arsenic, or mercury in our crabitats for the newly formed rust to leech from.This is pretty much common knowledge, but the first couple hits on google attest to it:http://www.natural-living-for-women.com ... -------And I've been using those metal mini-cubes for years in my crabitat and they rust in the moist substrate. I also had some rusty screws in my waterfall (the zoo-med waterfall is held together by two iron screws). No ill effects noted.----------Not all metal ions are toxic or carcinogenic. Only a few heavy-metal ions are known to be unsafe: Cr (chromium), Ni (nickel), As (arsenic), and Cd (cadmium).Stainless steel is coated in chromium, so stainless steel should be avoided.And here's a few articles on which heavy metals are dangerous:http://www.ciwmb.ca.gov/LEAAdvisory/56/ ... tmlShowing arsenic, cadmium, chromium, and nickel to be toxic for invertebrates or aquatic life.beryllium is toxic, but not likely to build up in waterlead and mercury of course we all know as toxic, but they don't represent the bulk of heavy metal ions in waterCopper and zinc we've talked about in another thread. It is toxic in high quanitities, but is a necessary element for all life in small quantities.----------Metal in general isn't necessarily bad. It a misconception based on fact, caused by overgeneralization. Heavy metal ions in water (listed above) are dangerous to crabs. But not all metal creates toxic ions in water, and not all metals are heavy metals. I think it started with the fact that heavy metal ions need to be removed from water through the use of a tap water conditioner, and got overgeneralized to any metal in the crabitat being dangerous to crabs.Sometimes facts are propagated from website to website and caresheet to caresheet, and eventually become common knowledge fact. Except that a fact might be true or false, and I enjoy challenging them from time to time.I can't claim I'm right either. Well, it's not a case of my view vs. someone else's. I just haven't found evidence that rust is harmful yet. But someday we could.