Strand of tissue passing longitudinally through the shell of a cephalopod mollusk
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Siphuncle" – news · newspapers · books · scholar · JSTOR(December 2008) (Learn how and when to remove this message)
A cross-section through a Nautilus shell, showing a narrow siphuncle connecting the chambers of the shell
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 septa (walls) dividing the 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 mollusc organ of the same name.[1]
^Flower, Rousseau H. (1964). "Nautiloid shell morphology" (PDF). New Mexico Bureau of Mines and Mineral Resources, Memoir. 13: 1–78.
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles...
typically had ventral siphuncles like ammonites, although often proportionally larger and more internally structured. The word "siphuncle" comes from the Neo-Latin...
perforated by the siphuncle, a fleshy tube which runs through each of the internal chambers of the shell. Surrounding the fleshy tube of the siphuncle are structures...
sections, straight to sinuous sutures, and a tubular, generally central siphuncle. Having survived relatively unchanged for hundreds of millions of years...
release of egg and sperm, in the nautilus a string of tissue called the siphuncle goes through all the chambers, and the eight plates that make up the shell...
of the siphuncle. The surface of the siphuncle is supported by septal necks which are holochoanitic, meaning that they fully sheath the siphuncle and extend...
body chamber transversely constricted, and a subcentral orthochoanitic siphuncle. The surface is ornamented by a network of fine lirae (Sweet 1964:K224)...
Agonititida. Agoniatitids are primitive ammonoids with a ventral retrochoanitic siphuncle (septal necks point to the rear) reflective of their nautiloid ancestors...
to some gastropods was used to support this view. The development of a siphuncle would have allowed the shells of these early forms to become gas-filled...
the genus Nanno in that the siphuncle in Nanno fills the entire apical portion of the shell while in Endoceras the siphuncle is ventral even there with...
Pseudactinoceratinae). The siphuncle is central or located between the center and venter. Necks are cyrtochoanitic, otherwise siphuncle shape and structure are...
twists the internal organs so the anus lies above the head. = Septa = Siphuncle Volborthella, some fossils of which predate 530 million years ago, was...
cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early...
some gastropods was used in support of this view. The development of a siphuncle would have allowed the shells of these early forms to become gas-filled...
ventral siphuncle instead. The siphuncle in Loganoceras is subcentral. The related Romingoceras is more curved, also with a ventral siphuncle. All three...
as endogastric, assuming the small siphuncle on the inner margin to be ventral. Known for sure dorsal siphuncles do not appear until later in the Early...
orthoconic to cyrtoconic shells that may be long or short with a narrow siphuncle invariably in contact with the ventral wall and sutures uniformly with...
On the ventral (bottom) side of the cuttlebone is the highly modified siphuncle; this is the organ with which the cuttlebone is filled with gas or liquid...
externally, but has a siphuncle with a trapezoidal aspect to its siphuncle segments. Perimecoceras has similar concave siphuncle segments but is tubular...
from North America, belonging to the family Endoceratidae, in which the siphuncle takes up the entire apex. Foestellites, named by Kobayashi, 1940, is based...
section, having a deeply impressed dorsum and a ventral to subcentral siphuncle, known from the Lower Ord (U Canad) of North America. It differs from...
of concavo-convex chambers linked by a centrally-placed tube called a siphuncle. There is a tendency for the chambers to develop cameral deposits, which...
Devonian. Discosorids are unique in the structure and formation of the siphuncle, the tube that runs through and connects the camerae (chambers) in cephalopods...
with the distance between the dorsum and siphuncle increasing while the separation between the venter and siphuncle remains at a more or less constant. Related...
this issue. Bisonocerids are similar to endocerids in many respects. The siphuncle was broad and positioned ventrally in the shell, which ranged in shape...
changing the gas-to-liquid ratio in the chambered cuttlebone via the ventral siphuncle. Each species' cuttlebone has a distinct shape, size, and pattern of ridges...
in the siphuncle, reaching as much as halfway between septa in the chambers; sparse cameral deposits and apparently none within the siphuncle. The inclusion...
only those ellesmerocerids that have straight transverse sutures and siphuncles with concave segments and thick connecting rings. Protocycloceratidae...
Bassleroceras. Septa are close spaced, the living chamber short, the siphuncle close to the venter. The type species, Leonoardoceras parvum Flower was...
Global Information
