Why Isn't Copper Very Toxic To Vertebrates?

[Revision17]

I've done some searching on google and can't seem to find out why vertebrates are much more tolerant of copper than invertebrates. It seems almost arbitrary that in addition to getting a super sweet backbone, vertebrates get a super cool immunity to copper. Is there something inherent in the vertebrate body plan which makes them copper tolerant?

The whole invertebrate copper intolerance.. it seems like it would make more sense to me if only a single group (like arthropods) or a few groups happened to be copper intolerant. Or if only animals which used hemocyanin were intolerant. But from what I've seen everything from shrimp, to snails, to xenia (reefkeeping did an article on "reef safe" ich cures awhile back, and they added copper sulfate to a tank with a xenia in it.. which died quickly) are coper intolerant.

Anyone more biology oriented than me want to help shed some life on this?

 

[Colin_T]

Mammals, birds & reptiles have iron based blood. Many inverts, have copper based blood. When mammals have too much iron in the body they die. Likewise when inverts get too much copper in their body they die.
It also comes down to body mass with mammals having bigger bodies thus allowing them to ingest more copper (and other chemicals) with fewer problems. Most inverts are tiny by comparison and only require tiny amounts of chemicals (not just copper) to kill them.

 

[Bignose]

It all depends on what you consider "not very toxic". Because the toxic concentration of copper for the average fish is much, much lower than the toxic concentration for humans. Sure, it isn't as low as the toxic concentration for the average invertebrate, but copper is one of those things that is often overlooked. The toxic concentration of copper for fish is actually so low that in most countries, if the water has that concentration of copper, it is considered perfectly safe for human consumption.

 

[FishStick101]

Mammals, birds & reptiles have iron based blood. Many inverts, have copper based blood. When mammals have too much iron in the body they die. Likewise when inverts get too much copper in their body they die.
It also comes down to body mass with mammals having bigger bodies thus allowing them to ingest more copper (and other chemicals) with fewer problems. Most inverts are tiny by comparison and only require tiny amounts of chemicals (not just copper) to kill them.

very good reply . and the other reply is correct as well ..because to much copper will kill any fish!

 

[Mr Bliss]

Mammals, birds & reptiles have iron based blood. Many inverts, have copper based blood. When mammals have too much iron in the body they die. Likewise when inverts get too much copper in their body they die.
It also comes down to body mass with mammals having bigger bodies thus allowing them to ingest more copper (and other chemicals) with fewer problems. Most inverts are tiny by comparison and only require tiny amounts of chemicals (not just copper) to kill them.

But if the metal used in the oxygen-carrying metalloprotein were the main factor in determining toxicity, wouldn't you expect iron to be much more toxic than copper to vertebrates? Because this doesn't seem to be the case. The LD50 of copper to rats is almost exactly the same as the LD50 of iron. For fish (and apparently all aquatic organisms), copper is 10 - 100 times more toxic than iron. This is true for aquatic invertebrates as well, but they tend to have lower overall tolerances for both iron and copper. And to make it more complicated, not all vertebrates have a higher tolerance to copper compared to inverts: based on a quick search for publications, the 96h LC50 of copper for pond snails is reported to be ~0.4 ppm, and 0.5 ppm for Cherax destructor, a species of crayfish; for Koi this toxicity level is considered to be 0.2 - 0.3 ppm and for some sensitive fish it goes down to 0.02 ppm and beyond.

But clearly the 50% lethal concentrations don't tell the whole story, since it's fairly common knowledge that small amounts of copper can gradually kill many invert species from a tank (or natural environment) while leaving the fish intact. My gut feeling is that this is because vertebrates have more sophisticated detoxification systems, most importantly livers. At low copper concentrations, vertebrates would be able to remove any excess copper from their system without ill effects. There's a hereditary condition called Wilson's disease that makes humans hypersensitive to copper in the long term; this is caused by a mutation that prevents the liver from processing copper normally. Instead copper accumulates in the body, causing a wide range of potentially lethal symptoms. It would make sense that animals that don't have livers to begin with (ie. invertebrates) would kind of have this hypersensitivity by default, although this is mostly speculation on my part.