? source of calcium for cephalopods ?

PaleoProgrammer

Pygmy Octopus
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#1
Hello!

I'm looking for information on the sources of calcium for modern cephalopods. Cuttlefish, Nautilus and Spirula need a large amount of calcium for the development of their shells. Whether they receive calcium from the food or absorbed it from seawater? The first version (with food as a source of calcium) seems more logical for me, but this is only an intuitive hypothesis. Could you help me with references to the literature containing such information?
 

DWhatley

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#2
This may help you get started on where to look but I don't have published references for the information.

I know that captive nautilus are fed shell on shrimp or crab to provide the needed calcium and it is assumed that this may be (at least in part) how they obtain it in the wild but there is little to no in situ observation of their feeding. From the observations and video @gjbarord has been documenting as well as information we have with aquarium animals (see the exotic forum and Doggy's thread for a bit of feeding dialog with biologists that have maintained them in the lab) it appears nauts are primarily scavengers but may be opportunistic if a live animal could be easily captured. Here is a thread that discusses calcium carbonate as part of a discussion on why there are not freshwater cephs and here is a thread where @robyn mentions that crab molts are a likely calcium carbonate source for nautilus. I found one more tidbit from @cuttlegirl in a discussion about nautilus hatchlings

S. bandensis cuttlefish hatchlings eat the whole shrimp when being fed shore shrimp (as do octopuses who have no known need for calcium) but I don't know if they eat the shells of larger shrimp or crab. The octopuses I have kept ate neither the tougher shell of table shrimp nor the shells of crabs. I think @cuttlegirl made a comment about the cuttles source for carbonate not long ago but I don't remember/can't find the the post (she should see this note and respond). I want to say she stated that they get their carbonate from the water but don't hold me to that.

We don't have much info at all on Spirula and the little that is posted suggests very little is known about their lifestyle and eating habits.
 

DWhatley

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#6
but, aren't you on summer break? Then again, I kept Chase (almost 5) for a couple of weeks while my son and daughter-in-law were finding a house and my FitBit showed double the activity :biggrin2:
 

gjbarord

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#7
@PaleoProgrammer The real problem is all of these assumptions we have, especially with nautiluses. It certainly makes sense to use calcium in the diet for shell growth but the habitat of nautiluses in the deep sea does not suggest that they have a "huge" supply of food available. Based on some captive studies that I've done, diet certainly plays a role in at least the rate of shell growth....

Greg
 

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