Editing Siphuncle (section)

{{short description|Strand of tissue passing longitudinally through the shell of a cephalopod mollusc}}
{{Refimprove|date=December 2008}}[[Image:Siphuncle.gif|thumb|right|A cross-section through a ''[[Nautilus (genus)|Nautilus]]'' shell, showing a narrow siphuncle connecting the chambers of the shell]]The '''siphuncle''' is a strand of [[biological tissue|tissue]] passing longitudinally through the [[mollusc shell|shell]] of a [[cephalopod]] [[mollusc]]. Only cephalopods with chambered shells have siphuncles, such as the extinct [[ammonite]]s and [[belemnite]]s, and the living [[nautilus]]es, [[cuttlefish]], and ''[[Spirula]]''. In the case of the cuttlefish, the siphuncle is indistinct and connects all the small chambers of that animal's highly modified shell; in the other cephalopods it is thread-like and passes through small openings in the [[Septum (cephalopod)|septa]] (walls) dividing the [[Camera (cephalopod)|camerae]] (chambers). Some older studies have used the term '''siphon''' for the siphuncle, though this naming convention is uncommon in modern studies to prevent confusion with a [[Siphon (mollusc)|mollusc organ of the same name]].<ref name=":0">{{Cite journal |last=Flower |first=Rousseau H. |date=1964 |title=Nautiloid shell morphology |url=https://geoinfo.nmt.edu/publications/monographs/memoirs/downloads/13/Memoir-13.pdf |journal=New Mexico Bureau of Mines and Mineral Resources, Memoir |volume=13 |pages=1–78}}</ref>