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The chambered nautilus (Nautilus pompilius), also called the pearly nautilus, is the best-known species of nautilus. The shell, when cut away, reveals a lining of lustrous nacre and displays a nearly perfect equiangular spiral, although it is not a golden spiral. The shell exhibits countershading, being light on the bottom and dark on top. This ...
Nautilus (from Latin nautilus 'paper nautilus', from Ancient Greek ναυτίλος nautílos 'little sailor') [3] are the ancient pelagic marine mollusc species of the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina .
Nautilus belauensis. Much of what is known about the extinct nautiloids is based on what we know about modern nautiluses, such as the chambered nautilus, which is found in the southwest Pacific Ocean from Samoa to the Philippines, and in the Indian Ocean off the coast of Australia. It is not usually found in waters less than 100 meters (328 ...
Argonauts surrounding the Nautilus, in Jules Verne's novel Twenty Thousand Leagues Under the Seas. Argonauts are featured in Twenty Thousand Leagues Under the Seas, noted for their ability to use their tentacles as sails, though this is a widespread myth. A female argonaut is also described in Marianne Moore's poem "The Paper Nautilus".
Nautilus have unique sensory organs, which differ from related genera in several ways. Unlike other cephalopods, the eyes of Nautilus species lack ocular muscles and instead move via a stalk, which contains both muscle and connective tissue. Additionally, Nautilus eyes lack any lens or cornea and only have an aperture to allow for light.
Cutaway of a nautilus shell showing the chambers. The phragmocone is the chambered portion of the shell of a cephalopod.It is divided by septa into camerae.. In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camerae are linked by a siphuncle which determines buoyancy by means of gas exchange.
The Nautilaceae are represented by Nautilus and Allonautilus, genera included in the Nautilidae. Species in the Nautilaceae are generally smooth and involute with straight to strongly sinuous sutures and a small siphuncle. Some groups have sinuous plications or ribs.
The chambered part of the ammonite shell is called a phragmocone. It contains a series of progressively larger chambers, called camerae (sing. camera) that are divided by thin walls called septa (sing. septum). Only the last and largest chamber, the body chamber, was occupied by the living animal at any given moment. As it grew, it added newer ...