Molluscs
Chambered nautilus
Nautilus pompilius
A true living fossil whose shape has barely changed in over 500 million years, it navigates using a chambered shell that works like a natural submarine.
🗺️ Geographic range
Deep reefs of the Indo-Pacific, notably around Fiji, the Philippines and Australia.
📊 Population
Not formally evaluated by the IUCN at the species level, but listed on CITES Appendix II since 2016 due to the documented decline of certain populations from overfishing for the shell trade.
⚠️ Threats
Overfishing for the shell trade
Documented decline in some populations linked to overfishing, which led to its listing under CITES Appendix II in 2016.
Source: French National Museum of Natural History
Habitat
- Pacific Ocean · High seas / open water · Mesopelagic zone · Permanent
Behaviour
- Diet
- Small crustaceans, dead fish and carrion detected by smell.
- Hunting
- Rises at night toward shallower water to feed, descending again by day.
- Reproduction
- Very slow growth, sexual maturity reached around age 15.
Physiology
- Anatomy
- A spiralled shell divided into gas-filled chambers.
- Adaptations
- Regulates its buoyancy by adjusting the gas-to-liquid ratio in its shell's chambers, like a submarine's ballast.
🔗 Web of marine life
Predators
⚡ Its extraordinary abilities
- A shape virtually unchanged for over 500 million years
- Regulates its depth like a submarine, using a shell with gas-filled chambers
🏆 Records
The longest-unchanged known body form in a cephalopod
Considered a living fossil, virtually unchanged for over 500 million years.
Source: French National Museum of Natural History
If you cross paths with this animal…
Risk: None.
Behaviour: Slow and discreet, mostly active at night.
Advice: A species threatened by fishing for the shell trade: avoid buying nautilus shells.
💡 Did you know?
- Can have up to 90 tentacles, without suckers, unlike octopuses and squid.
- Its shell's near-perfect logarithmic spiral has inspired generations of engineers and artists.