Nice pics of Loligo subulata on (North Sea - Skagerrak):

http://www.tauchprojekt.de/fotos/Allotheutis%20subulatat_Nordsee%20Kalmar .htm

English comment at the bottom of the page.

The dark spot in one of the pictures reminded me of the way two of the hearts look on the Mercatoris. It occurred to me that I did not know if other cephs share the multiple heart or the circular brain biology. I am assuming not but thought to ask.

The dark spot in one of the pictures reminded me of the way two of the hearts look on the Mercatoris. It occurred to me that I did not know if other cephs share the multiple heart or the circular brain biology. I am assuming not but thought to ask.

All cephs, including Nautilus have the donut-brain, although there are some variations... in particular, Nautilus lacks the vertical lobe that's been shown to be important in memory formation in other cephs, yet (as Robyn has shown!) they are quite capable of learning, so they probably have a similar brain area that hasn't been identified. Anyway, the gross neuroanatomy is pretty consistent across coleoids and Nautilus is surprisingly similar, considering how long ago the lineages split. The brain is more like a "nerve cord" with the individual lobes less distinct than most other cephs, and of course, there are no chromatophore lobes, since it has no chromatophores. The optic lobes are grossly similar to those of coleoids (in both, they stick out from the sides, and aren't part of the "donut" brain.) There's some difference, though, in that the image on the optic lobes isn't "flipped upside down" like it is in coleoids (except Vampyroteuthis) and the optic lobe's detailed anatomy is a bit different as well. They make up for some of this by having more sophisticated olfactory organs and lobes, though: Young reports from a discussion with Saunders that Nautilus lives by "smelling and groping" rather than "visual spotting and attacking" like most coleoids. (Although, frankly, many octopuses seem as happy with tactile hunting as visual.)

I'm less sure about the hearts, but I have books to substitute for my ignorance :read:... all cephs including Nautilus have 3 hearts, one central "systemic" heart and 2 "branchial" hearts for the gills. However, one of the main relics(?) that makes Nautilus different from all the coleoids is that Nautilus has 4 gills rather than the two found in all other cephs. I put the (?) for relics, though, because there are some strangenesses: the gills develop sequentially in the embryo, which makes one wonder if the 4 gills is a recent adaptation in Nautilus rather than the primitive condition... we don't have any other ancient or modern nautiloids or ammonoids to compare it to.

Thanks Monty. I was not sure if the hearts and brains were something that tied them together or not and I either did not ingest the info when presented or have only read enough repetition to "know" the octo configuration.