Field of Science

Day of the Tentacle

Apparently yesterday was International Cephalopod Awareness Day. This is one of the problems of living on the other side of the world from the blogging majority - by the time I discovered that October 8 was Cephalopod Day, October 8 was, for me, pretty much over. Mind you, except for Ben D at Principles of Parsimony, Cephalopod Awareness seemed to mostly be Neocoleoid Awareness. Unfortunately, modern cephalopods are something of a fragment of their former selves. Of the three traditional subclasses, only one - the coleoids - survives in any great numbers. 'Nautiloids'* are represented by only a single living genus, the eponymous Nautilus. The third class, the ammonoids (of which ammonites are the best-known members), never made it past the end of the Cretaceous.

*The inverted commas are because Nautiloidea in the traditional sense is a paraphyletic group that contains the ancestors of the other subclasses.

But once these creatures ruled the sea. The image above (from here) is of the largest known ammonite, Parapuzosia seppenradensis, with a diameter of about 2.5 metres. That's a lot of calamari.

Oh yes, and while looking stuff up for this, I came across one of the more disturbing article titles I've seen - "Implosion of living Nautilus under increased pressure". Ick. Can you imagine the grant proposal?


Kanie, Y., Y. Fukuda, H. Nakayama, K. Seki & M. Hattori. 1980. Implosion of living Nautilus under increased pressure. Paleobiology 6 (1): 44-47.


  1. seemed to mostly be Neocoleoid Awareness

    Well, there is also Clarrie's knitted ammonites. But thanks for covering some of the incredible diversity of cephalopods' ancestry. And thanks for participating in ICAD 2007.

  2. What's grosser than an imploding Nautilus? Why an imploding Parapuzosia of course!

    I remember reading that some American giant ammonites were supposedly pathologic. Parasites were supposed to have messed up their reproductive organs and turned them into oafs.

    Any similar story with Parapuzosia?

  3. Damn you, Neil! I was supposed to be working! Procrastination is just too easy...

    I've now looked up pathologic gigantism in ammonites, and there do appear to be recorded cases. It's not unknown in other animals, either - I already alluded to it in the Planctosphaera post. Basically, the individual never reaches sexual maturity and just never stops growing. I haven't been able to find if there are any signs that a given specimen is a pathologic giant or not, and I haven't found if there is any suggestion that Parapuzosia seppenradensis is a pathologic giant. I tried to find out whether multiple large specimens were known for P. seppenradensis, but so far no luck.

  4. Thanks for looking into it...lord knows I couldn't bother to look up the refs myself, what with 80 pages on pre-plate tectonic interpretations of the Permo-Triassic sitting on my desk...ignoring them is hard work!

  5. In the collection of the paleontological museum of Tübingen there are several striking ammonites and many other great fossil cephalopods. You can see some of the photos here:
    The one on the wall is only a cast of the original, but anyway it is amazing to imagine the huge size of this animal.


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS