The chambered nautilus (Nautilus pompilius) is a species of marine invertebrate that can be found in the South Pacific and sometimes found in reefs near Austrailia, Japan, and Micronesia. It gets its name from the multiple chambers found in its shell encasing most of its body.
As a carnivore, it feeds on both underwater carrion and detritus, as well as living shellfish and crab. Mainly scavengers, chambered nautiluses have been described as eating “anything that smells”. This food is stored in a stomach-like organ known as a crop, which can store food for a great deal of time without it denaturing.
The shell of the chambered nautilus fulfills the function of buoyancy, which allows the Nautilus to dive or ascend at will, by controlling the density and volume of the liquid within its shell chambers. This was found during research done in New Caledonia on Nautiluses whose shell chamber fluid densities were tested at various depths, weeks apart. Generally speaking, chambered nautiluses inhabit a depth around 1000 feet, although further tests demonstrated that they can, and do, dive deeper. However, there are hazards associated with extreme depth for the Nautilus: the shells of chambered nautiluses slowly fill with water at such depths, and they are only capable of withstanding depths up to 2000 feet before imploding due to pressure. The chambered nautilus inhabits different segments of the shell as it grows, continuously growing new, larger “cells” into which it moves its internal organs as it grows in maturity. All of the smaller chambers, once uninhabited, are used in the method described above to regulate depth.
Nautilus shells were popular items in the Renaissance cabinet of curiosities and were often mounted by goldsmiths on a thin stem to make extravagant nautilus shell cups, mainly intended as decorations rather than for use. Small natural history collections were common in mid-19th-century Victorian homes, and chambered nautilus shells were popular decorations.
In 2011, scientists became alarmed at declining populations of nautilus resulting from overfishing, and have been studying world populations to determine the need for protection under the United Nations Convention on International Trade in Endangered Species.