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- Siphuncle abstract "The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, 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 walls dividing the chambers.The siphuncle is used primarily in emptying water from new chambers as the shell grows. Essentially what happens is the cephalopod increases the saltiness of the blood in the siphuncle, and the water moves from the more dilute chamber into the blood through osmosis. At the same time gas, mostly nitrogen, oxygen, and carbon dioxide, diffuses from the blood in the siphuncle into the emptying chamber. Note that the cephalopod does not pump up the shell; the gas moving into the chamber is a passive process, instead the energy is used in absorbing the water from the chamber.Removing water from the chambers of the shell reduces the overall density of the shell, and thus the shell behaves as a flotation device comparable to the swim bladder in bony fish. Typically, cephalopods maintain a density close to that of sea water, allowing them to swim with the minimum of effort. In the geologic past, many cephalopods grew to an enormous size (over ten meters in length) thanks to this.Generally, the siphuncle is unable to provide a way to change the density of shell rapidly and thus cause the animal to rise or sink at will; rather, the animal must swim up or down as required.The siphuncle found in fossilised cephalopods is assumed to have worked in the same general way. The siphuncle itself only rarely gets preserved, but many fossils show the holes, called septal necks (or siphuncle notches), through which the siphuncle passed. In most fossil nautiluses, the siphuncle runs more or less through the center of each chamber, but in ammonites and belemnites it usually runs along the ventral surface. In some fossil straight shelled nautiluses cylindrical calcareous growths ("siphuncular deposits") around the siphuncle can be seen towards the apex of the shell. These were apparently counterweights for the soft body at the other end of the shell, and allowed the nautilus to swim in a horizontal position. Without these deposits, the apex of the buoyant shell would have pointed upwards and the heavier body downwards, making horizontal swimming difficult. The siphuncle of the Endocerida also contained much of the organisms' body organs.".
- Siphuncle thumbnail Siphuncle2.png?width=300.
- Siphuncle wikiPageID "669046".
- Siphuncle wikiPageLength "3960".
- Siphuncle wikiPageOutDegree "27".
- Siphuncle wikiPageRevisionID "587080117".
- Siphuncle wikiPageWikiLink Ammonite.
- Siphuncle wikiPageWikiLink Ammonoidea.
- Siphuncle wikiPageWikiLink Baculites.
- Siphuncle wikiPageWikiLink Belemnite.
- Siphuncle wikiPageWikiLink Belemnitida.
- Siphuncle wikiPageWikiLink Biological_tissue.
- Siphuncle wikiPageWikiLink Blood.
- Siphuncle wikiPageWikiLink Carbon_dioxide.
- Siphuncle wikiPageWikiLink Category:Cephalopod_zootomy.
- Siphuncle wikiPageWikiLink Cephalopod.
- Siphuncle wikiPageWikiLink Cephalopod_size.
- Siphuncle wikiPageWikiLink Cuttlefish.
- Siphuncle wikiPageWikiLink Density.
- Siphuncle wikiPageWikiLink Endocerida.
- Siphuncle wikiPageWikiLink Fish.
- Siphuncle wikiPageWikiLink Fossil.
- Siphuncle wikiPageWikiLink Mollusc_shell.
- Siphuncle wikiPageWikiLink Mollusca.
- Siphuncle wikiPageWikiLink Mollusk.
- Siphuncle wikiPageWikiLink Nautilus.
- Siphuncle wikiPageWikiLink Nitrogen.
- Siphuncle wikiPageWikiLink Orthoceras.
- Siphuncle wikiPageWikiLink Osmosis.
- Siphuncle wikiPageWikiLink Oxygen.
- Siphuncle wikiPageWikiLink Phragmocone.
- Siphuncle wikiPageWikiLink Sea_water.
- Siphuncle wikiPageWikiLink Seawater.
- Siphuncle wikiPageWikiLink Spirula.
- Siphuncle wikiPageWikiLink Swim_bladder.
- Siphuncle wikiPageWikiLink Tissue_(biology).
- Siphuncle wikiPageWikiLink File:Siphuncle.gif.
- Siphuncle wikiPageWikiLink File:Siphuncle2.png.
- Siphuncle wikiPageWikiLinkText "Siphuncle".
- Siphuncle wikiPageWikiLinkText "endocone".
- Siphuncle wikiPageWikiLinkText "endosiphocone".
- Siphuncle wikiPageWikiLinkText "macrochoanitic".
- Siphuncle wikiPageWikiLinkText "molluscs".
- Siphuncle wikiPageWikiLinkText "siphuncle".
- Siphuncle wikiPageWikiLinkText "siphuncular".
- Siphuncle hasPhotoCollection Siphuncle.
- Siphuncle wikiPageUsesTemplate Template:Cephalopod_anatomy.
- Siphuncle wikiPageUsesTemplate Template:Refimprove.
- Siphuncle wikiPageUsesTemplate Template:Reflist.
- Siphuncle subject Category:Cephalopod_zootomy.
- Siphuncle hypernym Strand.
- Siphuncle type Article.
- Siphuncle type TelevisionShow.
- Siphuncle type Article.
- Siphuncle comment "The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula.".
- Siphuncle label "Siphuncle".
- Siphuncle sameAs خرطومچه.
- Siphuncle sameAs m.031crn.
- Siphuncle sameAs Vòi_hút_(chân_đầu).
- Siphuncle sameAs Q7525777.
- Siphuncle sameAs Q7525777.
- Siphuncle wasDerivedFrom Siphuncle?oldid=587080117.
- Siphuncle depiction Siphuncle2.png.
- Siphuncle isPrimaryTopicOf Siphuncle.