Chambered nautilus
Nautilus pompilius
— Where the name comes from
From the Greek nautílos, “sailor”, from naûs, ship: the ancients believed the animal hoisted its tentacles like sails. Pompilius recalls a fish that was said to escort ships.
— Facts
- Group
- Molluscs · Mollusca
- Order
- Nautiluses
- Habitat
- Coral reef slopes, between 100 and 500 m
- Range
- The western Indo-Pacific
- Size
- 15–20 cm of shell
- Diet
- Carnivore and scavenger
- Lifespan
- 20 years and more
— Characteristics
- 01
The shell is divided into sealed chambers linked by a siphuncle.
- 02
It regulates buoyancy by changing the ratio of gas to liquid in the chambers.
- 03
It has up to 90 tentacles, none of them with suckers.
— What sets it apart
A section through the shell is the logarithmic spiral of the textbooks: it grows by adding ever wider chambers without ever changing shape. It is often cited as an example of the golden spiral, but it is not one — its growth factor is close to 1.3, not 1.618. The nautilus is proof that nature is far fonder of logarithmic spirals than it is of the golden ratio.
