page_title: Nautilus
section_title: Senses
hierarchical_section_title: Nautilus / Physiology / Senses
caption_attribution_description: Nautilus pompilius&#160;L. 1758 English: Chambered Nautilus, at Pairi Daiza, Brugelette, Belgium
context_page_description: The nautilus is a pelagic marine mollusc of the cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina.
  It comprises six living species in two genera, the type of which is the genus Nautilus. Though it more specifically refers to species Nautilus pompilius, the name chambered nautilus is also used for any of the Nautilidae. All are protected under CITES Appendix II.
  Nautilidae, both extant and extinct, are characterized by involute or more or less convolute shells that are generally smooth, with compressed or depressed whorl sections, straight to sinuous sutures, and a tubular, generally central siphuncle. Having survived relatively unchanged for hundreds of millions of years, nautiluses represent the only living members of the subclass nautiloidea, and are often considered "living fossils".
  The word nautilus is derived from the Greek ναυτίλος nautílos and originally referred to the paper nautiluses of the genus Argonauta, which are actually octopuses. The word nautílos literally means "sailor", as paper nautiluses were thought to use two of their arms as sails.
context_section_description: Unlike many other cephalopods, nautiluses do not have what many consider to be good vision; their eye structure is highly developed but lacks a solid lens. Whereas a sealed lens allows for the formation of highly focused and clear, detailed surrounding imagery, nautiluses have a simple pinhole eye open to the environment which only allows for the creation of correspondingly simple imagery.
  Instead of vision, the animal is thought to use olfaction (smell) as the primary sense for foraging and for locating and identifying potential mates.
  The "ear" of the nautilus consists of structures called otocysts located immediately behind the pedal ganglia near the nerve ring. They are oval structures densely packed with elliptical calcium carbonate crystals.
caption: Head of N. pompilius showing the rudimentary eye, which functions similarly to a pinhole camera
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