Spirula spirula info. please!

BigSquid8Me

Blue Ring
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#1
Hey all!
I'm doing an amature (most amature . . . I'm a high school student) research project on Spirula spirula, but I have very few resources! I understand that Spirula is not a very well known species/genus, but it really fascinates me and I've been trying to get ahold of any info I can. I have "Cephalopod Behaviour" by Hanlon and Messenger, and Dr. James Wood as a guide/mentor, but I think I'm going to need a little bit more if I'm going to pull this off!
Any ideas?

~BigSquid
 

Tintenfisch

Architeuthis
Staff member
Moderator
#2
If you search the References section of Cephbase you get quite a few; among them:

Bruun A.F. 1943. The biology of Spirula spirula. Dana report. 24: 1-39.

Denton E.J., Gilpin-Brown J.B. and J.V. Howarth 1967. On the buoyancy of Spirula spirula. Journal of Marine Biological Association of the United Kingdom. 47: 181-191.

Herring P.J., Clarke M.R., von Boletzky S. and K.P. Ryan 1981. The light organs of Sepiola atlantica and Spirula spirula (Mollusca: Cephalopoda): Bacterial and intrinsic systems in the order Sepiodea. Journal of Marine Biological Association of the United Kingdom. 61: 901-916.

:read:
 

Phil

Colossal Squid
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#4
Hi, BigSquid8Me,

This link might be of use:

http://tolweb.org/tree?group=Spirula_spirula&contgroup=Sepioid_families

The Tree of Life pages are really very useful and full of detail. It may also be useful using the search function at the top of the screen on TONMO and inputting 'Spirula', you should then find a number of references to the animal under 'Physiology' and 'Fossils'. The squid occupies an interesting taxonomic postion and is a bit of a 'living fossil' itself.

Near identical Spirulidae are known at least since the Aquitainian of the Miocene period, about 23 million years ago and specimens of this age have been found in Japan. I can supply you with a reference for this tomorrow if you would like it.

Please help youself to this image if it is of use (it belongs to me!):

(TONMO.com edit - link no longer exists - forum software changed)

Hope that is of some help,

Cheers,

Phil
 

WhiteKiboko

Colossal Squid
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#6
BigSquid8Me said:
You wouldn't happen to know though how I would happen to get ahold of these references, would you?
Try local colleges or your local libraries if you're lucky... depending on where you go, a lot of journals can be found in digital form...
 

monty

Colossal Squid
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#7
WhiteKiboko said:
Try local colleges or your local libraries if you're lucky... depending on where you go, a lot of journals can be found in digital form...
There are a few pages on Spirula in Nixon & Young, _The Brains and Lives of Cephalopods_ if you can find a library near you that has that, too.

edit: Nixon & Young refer to an ancient Nature paper:

Schmidt, J. (1922) Live specimens of Spirula. Nature, London, 110, 788-90

many universities have been subscribing to Nature for many years, so that may not be too tough to find, even though it's so old. Of course, it's only 3 pages long, and the info isn't likely to be very current...
 

monty

Colossal Squid
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#8
I'd really love to hear all of you cladists describe your views on Spirula, actually-- it seems to fly in the face of the common belief that the specialized tentacles of the decapods developed after the coleoids lost their chambered shells...
 

monty

Colossal Squid
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#9
As an extension to my earlier question/observation about the 8-arms-2-tentacles aspect of spirula being at odds with the spiral shell, I also note that Nixon & Young report that slow and awkward little spirula has a giant fiber system related to that of other decapods, which would seem to suggest that fast squiddiness evolved before the loss of the coiled, chambered shell's buoyancy mechanism. The siphuncle in spirula is also positioned ventrally along the inside of the spiral, rather than centrally as in Nautilus, so I'm pretty sure that this is the only living ceph with this arrangement. (see the green picture at http://tolweb.org/Spirula_spirula/19989 )

I'm sure Kevin and Phil can list off the various ammonids and nautiloids that share this arrangement, but modern nautilus has a central siphuncle. (as an aside, I was surprised that I couldn't find much in siphuncle location in the otherwise brilliant "fossils and history" articles... perhaps someone with a more encyclopedic knowledge of such things could remedy that? or perhaps my article searching skills have failed me and someone will point out where I missed it...)

As a starter, and a hat tip memorial to Sir Denton, I'll transcribe a bit from Ward The Natural History of Nautilus(p.234):

Denton (1974) recognized the possible importance of decoupling in fossil nautiloids. Endocerids show obvious evidence of decoupling adaptations through the use of long septal necks, in a manner similar to that of Spirula. The very common Tertiary nautiloid Aturia showed a similar adaptation, but in a planispiral shell similar to that of Nautilus, rather than in a straight shell as in the Paleozoic endocerids. The long septal necks of Aturia would effectively produce decoupling at even lower percent emptying volumes than in Nautilus (Ward 1980) (Fig 7.17). Aturia evolved at the end of the Cretaceous Period, and became the most diverse nautiloid genus of the Cenozoic. Fossil Aturia can be found from Cenozoic marine deposits on most continents. In contrast to the centrally localted siphuncle of most nautiloids, and the outer marginal position of the siphuncle in most ammonoids, the siphuncle in Aturia is dorsal in position on the whorl, or placed against the inside shell wall. In this characteristic it resembles the clymeniid ammonoids of the Paleozoic, the endoceratid nautiloids of teh Paleozoic, and modern Spirula. The living position of Aturia was such that the last formed chamber would be in a position similar to that of Nautilus, with connecting rings of the siphuncle oriented vertically. Well-preserved specimens of Aturia from the Pacific Coast of North America sometimes still preserve the original aragonitic composition of the shell and shell structures. From these specimens detailed ultrastructural studies can be made (Fig 7.18). The interior of the connecting rings show large fields of aragonitic needles, that would serve as fluid reserves. The long neck in neck structures of the siphuncles would cause decoupling to occur immediately after chamber formation. Aturia may have been among the most active and deeply living of the nautiloids, judging from the shell's large size, excellent streamlining, and siphuncle configurations.

Other examples of decoupling strategies include siphuncle migration in heteromorphic ammonites (Ward 1979, Klinger 1980) (Fig. 7.19). Most ammonites show no obvious mechanical adaptations to produce cameral liquid decoupling, although the position of the siphuncle in most ammonoids, against the outer margin of the whorl, would produce decoupling automaticall in those chambers situated high up on the whorl. Conversely, chambers located at the bottom of the whorl would always have liquid in contact with the siphuncle as long as liquid was present within the chamber.
Figure 7.19 shows a "tortonic heteromorphic ammonite" which has a siphuncle placed strategically to always be above the fluid level. The "decoupling" mentioned above means that the gas/fluid ratio in a chamber can be changed much more easily when the siphuncle's opening is not under the cameral liquid. To reduce confusion, spirula's orientation of the shell is the opposite of Nautilus, in that the last opening faces straight down rather than horizontally, so there is a little confusion about dorsal vs ventral, but the unusual configuration Spirula has is that the siphuncle is on the inside of the spiral, not the center as in Nautilus or the outside as in many ammonoids.

edit: I neglected to mention that this post was inspired by a discussion with hallucigenia, who got me thinking about spirula again and helped me past some of my paleo-ignorance, as well as having a "find links, look in books, and discuss results" IM session (much like this) :oops:
 

Architeuthoceras

Architeuthis
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#10
Spirula has an endogastric shell, it coils the opposite way (ventrally) of (?most) ammonoids and Nautilus, The shell of ammonoids and Nautilus are exogastric, their shell coils above the head (dorsally).

In this thread, more is said about the different layers of shell in the spirulids, and that maybe they are more like the the orthoconic bactritids than coiled ammonoids.
 

monty

Colossal Squid
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#11
thanks! Knowing the word endogastric led me to this: http://www.thecephalopodpage.org/FosCephs.php which answers a few questions and raises some as well.

It seems like someone should be doing some genomic analysis to compare spirula to nautilus and to other coleoids. And the cirrate octopods and vamyroteuthis to more typical coleoids.

It still seems to me that spirula's shell geometry throws a big wrench into all the standard clade diagrams, and yet it seems to just not get discussed much... but maybe I'm just not looking in the right places, hence this thread! (the usual "I am an ignorant computer scientist, not a real bio-/palaeo-/teuth- or other -ologist" caveats apply)
 

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