What does siphuncle mean?
A siphuncle is the slender tubular passage that connects the chambers of a cephalopod shell. In living nautiluses, it allows fluid to move between chambers, enabling the animal to control its buoyancy and adjust its depth in the water. The structure can also be preserved in fossil shells, making it useful to palaeontologists studying the growth and biology of ammonites and related animals. The word is principally used in zoology, palaeontology, and the study of shells. Although the term may sound similar to siphon, it refers specifically to the tube within a cephalopod shell rather than a pipe or tube for carrying liquid.
nounA narrow tubular passage running through the chambers of a cephalopod shell, especially that of a nautilus or ammonite. It helps the animal regulate its buoyancy by allowing fluid to pass between chambers.
- The narrow tube or canal connecting the chambers of a cephalopod shell, used in the regulation of buoyancy.
"The nautilus adjusted its depth by changing the amount of fluid in the chambers connected by its siphuncle."
"Fossil collectors examined the coiled shell and its visible siphuncle."
"In a living nautilus, the siphuncle connects the shell's chambers and helps control the animal's buoyancy."
The plural is used when referring to the connecting tubes of multiple cephalopods or shells.
"Researchers compared the siphuncles of several fossil nautiluses."
A nautilus can raise or lower itself in the water by using the delicate tube running through its shell like a sophisticated internal ballast system.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does siphuncle come from?
The word comes through Latin from Greek, combining the root associated with siphon, a tube or pipe, with a diminutive suffix. The Latin form siphunculus referred to a small tube or passage. Its scientific use became established for the connecting tube within cephalopod shells.
Related word forms
How siphuncle is actually used
This is chiefly a technical zoological and palaeontological term. It is usually used with reference to cephalopod shells, including those of nautiluses, ammonites, and squids.