Argonauts

[Phil]

OK, it seems a pity that these obscure little octopods are so rarely mentioned on these pages.

What's going on with these animals? Here we are with this advanced octopus that insists on creating a very ancient ammonite-like shell in which to breed its young. How is this? Is this coincidence or not?

How well studied are these animals? Has anyone ever kept them in captivity?

 

[Burstsovenergy24]

Never heard of them, but now youve sparked my interest! So the shells look like this?

 

[NickA5582]

I've read about them a while go, I think they've been kept before but the longest was 2 weeks, SOS said he kept one for a few days....

http://www.dal.ca/~ceph/TCP/Argo.html

 

[neptune]

They are amazing!!

That pic on Ceph Page makes them look as if their body is covered in suckers!

 

[fluffysquid]

There is some good information and pictures of argonauts in the book Cephalopods: A World Guide

 

[Architeuthoceras]

Aint those the guys what sailed with Jason, after the golden fleece?

Dr. Woods posted this site on the Ceph list.
Argonauts

If the argonaut has the ability to secrete a shell with its arms, why would it need to copy an ammonoid shell. If the argonaut was using empty ammonoid shells for a nest in the mesozoic how did it remember what an empty ammonoid shell looked like by the time they developed the ability to secrete one that looked like an ammonoid shell? Seems to me it would be easier to just use some other shell for a nest, than to spend years trying to figure out how to secrete one. This would foul-up my theory that the octopods learned to coil their arms to look like a school of ammonoids (pedators would grab an arm, thinking it was an occupied shell).

There is probably a little "coiled shell" in all of us.

They are fabulous animals.

 

[Phil]

Another problem with linking ammonoids to argonauts is the length of time elapsed between the extinction of the ammonites, i.e 65 mya, and the earliest recorded argonaut, i.e 25mya. How could an octopod retain some form of ancestral memory for 40 million years before deciding it suddenly wanted to secrete ammonoid-type shells? (Argonaut date here taken from the Tree of Life pages). Even given that the fossil record is incomplete, this seems an unlikely amout of time to have passed with no fossil argonaut shell remains if they were out there in the immediate post-Cretaceous.

In addition, the chambered ammonite shell was composed of aragonite, the unchambered argonaut calcite. The more one thinks about the theory the more ridiculous it sounds! It's all coincidence in appearance, I'm sure.

= x

 

[cthulhu77]

The more you see and learn, the more things just don't seem to make much sense...I am sure there is an underlying rythym to all of it, but I , for one, seem to be left out of the dance!
Fascinating subject Phil...it never occured to me at all...most perplexing.
greg

 

[Architeuthis]

I haven't heard much about them or seen one. All I know is people call it a paper nautilus.

 

[Argonautautidae]

Hi,

I collect cephalopod shells and specialise in animals of the genus Argonauta and Nautilus (though I couldn't even spell the screen-name I wanted right ). Does anyone how many species there are?
I'm sure that more than one species is being treated under the name Argonauta hians due to the diversity in shell shape, size and colour.

Michael.