Cross-section of a
Chambered Nautilus (fig.) shell.
It contains a
series of separate chambers, sealed by thin partitions and arranged in a more or
less logarithmic spiral. The animal lives in the largest chamber, which opens to
the outside. The remaining chambers are filled with gas, and by adjusting the
amount of liquid in them, the Nautilus is able to adjusts its buoyancy and to
dive.
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