Argonauts

[Argonautautidae]

I've added 11 new photos to my Argonauta photo album, if you'd like to have a look: http://www.picturetrail.com/gallery/view?p=999&gid=4081363&uid=2101892&members=1

Pics 9-11: Argonauta nodosa. Typical Australian form (in my opinion the most magnificent type), Brazilian form (more elongate shell with less developed tubercles and ribbing) and an intersting specimen of an Australian A. nodosa with slightly exagerrated features (and even two small "spikes" like those on A. argo or A. hians "No. 2").

Pics 12-14: Argonauta argo. Typical Australian form, quite a large specimen (about 18 cm). Then there is the South african form which is usually much smaller and more elongate, which underdeveloped "spikes" (some specimens lack them completely). The third is a specimen from Taiwan waters. A. argo shells from this region seem to vary widely in shape and form.

Pic 15: An example of quite considerable shell restoration in a medium-sized specimen of A. argo.

Pic 16: Freak specimen of A. hians from Taiwan.

Pics 17 & 18: Two old pics showing both sides of my A. hians (122 mm) from Taiwan.

Pic 19: An old pic of my Argonauta nouryi (93.9 mm) from Baja California. (Photo courtesy of Guido T. Poppe who I bought it from).

Well, that's most of the major species covered now.

Michael.

 

[cthulhu77]

Very nice Gallery...great pictures, and great information!
thanks!
Greg

 

[Phil]

Wow,

Thanks for the fascinating detail and images. The argonauts are a more varied group than I had realised, it's fascinating to see the variation in form in the shells on your website.

As for Nautilus repartus, from searching around on the net it seems that there seems to be no consensus about it. However most sources seem to indicate that it is a synonym of N.pompilius, just a rare and large Indonesian subspecies. I'd love to see images of your collection of Nautilus shells, especially. Allonautilus!

Cheers,

Phil

 

[Argonautautidae]

I've only got one Allonautilus at the moment: a quite large specimen of Allonautilus scrobiculatus (184 mm) from Milne Bay, New Guinea. As you can probably see from the photo it still needs some cleaning to remove the remenants of the periostracum.

The second Nautilus photo is of one of my favourite specimens; a very large Nautilus pompilius - 235 mm in size. This shell is very thick-walled and heavy. From Western Australia.

Michael.

 

[Steve O'Shea]

Well, I'm absolutely tickled pink! Back in 1999 when I put the last piece of work out on New Zealand Argonauta species (recognising A. nodosa on the basis of animals and shells, and A. argo on the basis of shells only, excluding A. boettgeri from the New Zealand region (the species was included in error based upon a misidentification by Massy 1916)), I had only 2 small animals of A. argo available for comparison, loaned from the British Museum. It was very difficult to dissect this material (given it was on loan), and specimens that could be definitively identified as A. argo (given the shell was present) were extremely rare in collections (to the best of my knowledge). Consequently I was unable to contribute anything to our knowledge of the anatomy of this species.

Debbie Freeman, of the New Zealand Department of Conservation, also the whiz that gave us those sensational photographs of the sperm whale with the gouges over the head (after a rather serious battle with the colossal squid), has just contacted me and sent the following photos of an Argonauta argo just collected off central-eastern New Zealand, for which the shell, animal and eggs are all available. We've now finally got a specimen of this species from New Zealand waters, based upon a record of the animal, and accordingly can now examine it in greater detail than has hitherto proven possible, and describe both external morphology and internal anatomy. You'll not find a half-decent account of the anatomy of A. argo anywhere (or at least I was unable when researching the group).

I'll get this online as soon as I can, when I get the animal.

Debbie, thanks a million, as always (and she's given us permission to post these pictures).
Steve

 

[Steve O'Shea]

... and here's a couple of self explanatory pics, a juvenile female (minus shell), and a close up look at her eye (of no particular use to anyone, but one of my favorite shots).

 

[Argonautautidae]

Nice photos!

I was wondering if anyone else on these boards collects cephalopod shells?

Michael.

 

[Architeuthoceras]

I collect really old ones

 

[Phil]

Steve,

You've reached the press again!!!

http://xtramsn.co.nz/news/0,,3762-3263567,00.html

 

[Steve O'Shea]

I was down at the local jetty yesterday, doing the old food collection for the squid, yet again, and one of the chaps came running down down, someone I regularly exchange a few words with, near-slid on the algal covered ramp, and told me that "I was tickled pink" There'd be something on the radio that this rare octopus had been found and sent to me. I did scratch my head on this one, wondering who on Earth had said anything, and had a laugh. All I can think of is that some reporter, having a rather dull day at work, decided to check out what had been going on in the big wide world, found tonmo, found this and then quoted it on radio.

New Zealand is such a nice country you know

Either that or the Department of Conservation made mention of it somewhere in a press release.

The argonaut actually reached yesterday and is sitting in my freezer until next week. Another shell was also found yesterday.

 

[cthulhu77]

"Crikey!" exclaimed Dr. Steve O'Shea, "Ain't she a beaut?"
He then bombarded the reporter with various stories about how Neil Diamond was in fact the leader of the lost tribes of Israel, winner of the cosmic hula contest, and an all around nice guy.
"He's an all around nice guy!" said the Doctor, upon a follow up interview regarding sea badgers and nautiloid predation.
Film at eleven.

 

[monty]

I just got a copy of Monks & Palmer's Ammonites book, and find that they discuss two theories of why argonaut egg cases resemble ammonites, and I noticed this has been discussed here, too... unfortunately, they don't provide references for these, but they suggest:

1) early argonauts used empty, floating ammonite shells and evolved a way to patch up the shells using secretions from their arms, and "eventually got so good at it they could make a facsimile of an ammonite shell from scratch"

and

2) argonauts are "nude ammonites" that switched from using the shell for buoyancy to using it just for eggs (this is credited to Lewy 1996 but there's no bibliography to match this ref ) They cite two supporting bits: ammonites showed major sexual dimorphism, like argonauts, and other octopuses, particularly deep-sea octopuses but not other coleoids, have radula teeth that are "very like those found in fossil ammonites."

The Lewy paper is this one: http://geology.geoscienceworld.org/cgi/content/abstract/24/7/627

any comments? This is maybe more "fossils & history" but it fits in this thread, so I'll leave it here.

 

[OB]

And for those in a sentimental mood, please find this wonderful collection of A. nodosa drawings.

 

[Architeuthoceras]

As Phil points out in this thread, the first fossil Argonaut shells appear about 40mya, the ammonoids went extinct 65mya. It seems to me that the exhibitionist octopods would be more common closer to the 65mya time frame (both before and after) and most wouldnt have waited the 25ma to come out of the closet 40mya.

 

[marinebio_guy]

I'm actually just now righting a paper on the argonaut that I caught this past summer. Most of the papers I've read seem to go with the first theory that they used discarded shells found on the bottom and where able to at some point recreate it and also changed into a palagic life style. This was stated in a paper by Young (1960). The sexual dimorphism is probably evolved after it became palagic as it is more adventagous them. Just my thoughts.