A vocabulary of landscape — a landscape of words
1367 entries
nautilus
The nautilus is a cephalopod living in the last chamber of a coiled shell, with the sealed chambers behind it working as a buoyancy tank regulated through a tube that runs the length of the spiral. It has around ninety tentacles with no suckers, eyes that work as pinhole cameras with no lens, and it moves by jetting water. Its relatives dominated the ancient seas; six species are left, all in the Indo-Pacific.
Etymology
The word is Greek for a sailor, and it was applied on a misunderstanding. Ancient writers believed the animal spread a membrane above the water and sailed, using two tentacles as oars, which is not what a nautilus does at all. The description belongs to the paper nautilus, a small octopus that makes a thin case and is not a nautilus, and the two were confused for two thousand years.
Notes
The claim that a nautilus shell follows the golden ratio is repeated constantly and is not true. It is a logarithmic spiral, which means each turn is a fixed multiple of the last, but the multiple is not the golden ratio and varies between individuals. Nautiluses migrate vertically hundreds of feet each night to feed and drop back before dawn, and the shell would implode at around 2,600 feet.