Nautilus
Depth: 400 m · Twilight Zone
The nautilus carries its home as a striped spiral shell. Inside are many empty chambers full of gas, which it uses to rise and sink like a submarine. It is a living fossil and has drifted through the sea almost unchanged for over 500 million years.
For scientists
The nautilus controls its buoyancy by pumping gas and fluid through a thin cord (siphuncle) into the old chambers of its shell. With about 90 simple tentacles that have no suckers it feels and grips, and its pinhole eyes have no lens. At night it climbs the reef slope to feed on carrion and molted scraps, and by day it withdraws into the cool deep.
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