nautilus

Everyday

1. A sea animal related to the octopus and squid, which lives inside a coiled, striped shell divided into chambers. tree →
2. Nautilus: the name of famous submarines, including Captain Nemo's in Jules Verne's novel and the first nuclear submarine (a name). tree →

In the lessons

In science lessons the nautilus is an example of a mollusc and a «living fossil», as its relatives lived over 400 million years ago. Its shell is a spiral, used in maths to show spirals in nature. It floats by changing the gas in its shell chambers, like a submarine.

Examples

• A nautilus has up to ninety small tentacles. tree →
• The nautilus shell is a beautiful spiral. tree →
• The nautilus moves up and down by filling its chambers with gas or water. tree →
• In «Twenty Thousand Leagues Under the Sea», the submarine is called the Nautilus. tree →
• We saw a nautilus at the aquarium. tree →
• Ammonites were ancient animals like the nautilus. tree →
• She had watched jelly-fish and nautilus swimming a little way below the surface, and beautiful coloured sea-weeds floating about; but that was all. tree →

Note

Plural: nautiluses or nautili. Pronounced «NAW-ti-lus». A myth: the nautilus shell is often said to follow the «golden ratio» exactly, but real measurements show it does not.