Copper?

[Octomatt]

Hello -

I was watching what appeared to be a pretty old documentary on Octopus this past weekend on the "Science Channel." It was mentioned that an octopus' blood was "copper based." Is this true? If so, then why will an octo die in a tank than's been treated with copper? I'm not the most scientific man around here, so I thought I'd pose the question to the experts, because it just doesn't make sense in my head...

Matt

 

[rrtanton]

Same thought has struck me often. Cephalopods, like nearly all molluscs, use hemocyanin as their respiratory pigment. Respiratory pigments are really just an elaborate way to exploit the oxidation of various metals--that is, the tendency for various metals to bind to oxygen. A respiratory pigment is a complicated tangle of protein with an oxygen-grabbing metal at its center. The protein serves various functions which I don't remember terribly well in making easier for the metal to grab or let go of oxygen. In humans, the pigment is hemoglobin and the metal is iron--hence, the reddish color when oxygenated. In cephalopods, it's hemocyanin and the metal is copper, hence the blue color when oxygenated.

I haven't got a clue why copper is toxic to cephs...I couldn't quickly find an answer in a web search. Iron is not toxic to humans (at least, I presume it's not toxic in the same proportions as copper is toxic to cephs!) I know its toxic to a lot of marine invertebrates, but I don't know if the mechanism is the same in all and I know that in at least some, the mechanism is debated.

One website made an intriguing suggestion. It stated that hemocyanin was not as efficient or effective a respiratory pigment as hemoglobin, and that as a result cephs aren't able to supply themselves with oxygen as quickly as hemoglobin users. It raised the question: Given the remarkable nature of cephalopods, what would they be like if they sported hemoglobin? Could hemocyanin be a key limiting factor, without which they would be the dominating marine predators?

Resident cephologists...any thoughts on copper's mechanism, or on hemoglobin-bearing cephs?

rusty

 

[WhiteKiboko]

you know i had wrestled with this question several times but never asked our resident brains....maybe its akin to too much iron for a person, or that octos are much more sensitive, or maybe both....

 

[Octomatt]

Colin, any thought on this?

 

[Colin]

yes and no Matt

'Yes' i am interested but 'no' i wont pretend to understand the oxidation of metals in regards respiration at an extent to answer this properly.

Its not really my field of experience or interest. :?

However, i would suggest that this is worthy of following up and that perhaps someone would like to take it further and make an on-site article for future reference?

rusty said One website made an intriguing suggestion. It stated that hemocyanin was not as efficient or effective a respiratory pigment as hemoglobin, and that as a result cephs aren't able to supply themselves with oxygen as quickly as hemoglobin users. It raised the question: Given the remarkable nature of cephalopods, what would they be like if they sported hemoglobin? Could hemocyanin be a key limiting factor, without which they would be the dominating marine predators?

That's true and to combat this cephalopods have evolved specialised gills when compared to other molluscs. Part of this involves using the mantle like a pump to move water across modified gills at a higher rate. Also why 3 hearts are needed I suppose? Perhaps a ceph with haemoglobin would be the ultimate?

 

[Colin]

I had a scrape about online and so far nothing directly with cephalopods but this PDF file is quite interesting... You'll need Acrobat Reader by Adobe to read it though...

http://www.pesticide.org/chromated.pdf

C

 

[cthulhu77]

I actually feel rather stupid about this...I have known that copper is toxic in medium levels to inverts, but never why. I have posed the question to several other animal traders, and come up with nothing. Perhaps on monday, a trip to arizona state u for a meeting with an old professor...anyone have a definitive answer on this out there?
Greg

 

[Colin]

...still looking

 

[Mike Bauer]

What is the max amount of copper that ceps can withstand before they are effected. I used a copper test and found that I have .15 to .25 copper in my water. Will that kill cuttlefish?

 

[mikeconstable]

In the "Good Old Days" (1950's) copper was a no-no in any aquaria.
Copper as a medicament then started to appear, first as a cure for parasites of marines, now down to cures for green water in ponds!
Sea-water only contains about 0.0009 ppm Cu (internet sources) yet cephalopods obtain sufficient for their requirements. From Colin's pesticide link above it looks as if some organisms can extract / concentrate this element, so food may supply higher levels. Pesticides seem to rely on organisms concentrating copper to harmful levels.
Artificial sea-salt mixtures would appear to already contain some excess of copper (www.animalnetwork.com/fish2/aqfm/1999/mar/features/1/default.asp - gives numbers, but many look a bit peculiar? Seawater Cu =0.001, salt mixes circa 2.0, which would be 2000 times as much!). What are your numbers (ppm or ppb? - I don't know what levels test kits measure!).
Copper can be leached from pipes if acids are present (particularly acetic /organic acids). (I once caused a panic in a chemical works when I realised that a liquid raw material sample had a bluish tinge - the brass pipe fittings on a road-tanker had provided enough copper to cause big problems if it had been representative of the load).
To sum up, I avoid copper, but have never measured it when keeping cuttlefish.