Nautiluses live in the tropical waters of the western Pacific and Indian Oceans, spending most of their time along deep coral reef slopes between 150 and 700 meters below the surface. They’re found near the coasts and islands of countries like the Philippines, Indonesia, Papua New Guinea, Fiji, Palau, Australia, American Samoa, and New Caledonia.
Geographic Range
The chambered nautilus (Nautilus pompilius) is the most widespread species, ranging across a broad swath of the Indo-Pacific. Its range stretches from the Andaman Sea and coastal India in the west, through Southeast Asia, and out to Fiji and American Samoa in the central Pacific. The Philippines and Indonesia are historically major population centers, though heavy fishing has reduced numbers in both areas.
Other species have much smaller ranges. Nautilus macromphalus is found only around New Caledonia. The rarest relative, the crusty nautilus (Allonautilus scrobiculatus), has been spotted alive just a handful of times, all near Ndrova Island off Papua New Guinea. It was first seen alive in 1984, briefly again in 1986, then not recorded for 31 years until a 2015 survey caught one on camera approaching bait.
Depth and Daily Movement Patterns
Nautiluses don’t stay at one depth. They ride an elevator-like daily cycle, moving up and down the water column depending on the time of day. During daylight hours, they tend to sit relatively still at around 200 meters, with a measured average of about 196 meters across studied individuals. Some spend daylight foraging much deeper, between 489 and 700 meters.
At dusk, things get interesting. Around 6 p.m., nautiluses that spent the day at 200 meters dip down to 250 or 300 meters, then rise back over the course of about two hours. After that, nighttime becomes their most active period. They move continuously through a range of roughly 110 to 350 meters, though some individuals travel the full span from 100 to over 700 meters in a single night. This constant vertical migration likely serves both feeding and predator avoidance, letting them exploit food sources at different depths while staying hidden from visual hunters during daylight.
Their overall livable range extends from near the surface down to about 750 meters for the chambered nautilus. Below that, water pressure becomes too great for the shell’s gas-filled chambers. The optimal zone, where they spend the bulk of their time, falls between 150 and 300 meters.
Reef Slopes and Bottom Terrain
Nautiluses aren’t open-ocean drifters. They’re bottom dwellers, living close to the seafloor along the steep slopes that drop away from coral reefs. These reef slopes and continental shelf edges give them access to a wide range of depths within a short horizontal distance, which is essential for their daily vertical migrations. Picture a steep underwater hillside covered in coral and rock: the nautilus crawls and jets along this terrain, scavenging dead fish, crustaceans, and other organic matter that drifts down from shallower reefs above.
This attachment to specific reef structures also means nautilus populations tend to be isolated from one another. A group living on one reef system may have little contact with a group on another island hundreds of kilometers away. That isolation makes each local population more vulnerable to overfishing, since there’s no easy way for nautiluses from elsewhere to replenish a depleted area.
Where They Lay Eggs
Nautiluses attach their egg capsules directly to the seafloor, and temperature appears to matter more than depth in choosing a spot. Studies using chemical signatures in nautilus shells have reconstructed where eggs develop: in New Caledonia, egg incubation happens at roughly 140 meters deep, where the water sits around 21°C. In Fiji and the Philippines, eggs are laid between 170 and 230 meters, but the water temperature at those depths is the same 20 to 22°C range.
Embryonic development is extraordinarily slow. In aquarium settings, it takes up to a full year. During that entire time, the developing nautilus is fixed in one spot on the ocean floor, secreting its first shell chambers inside the egg capsule. Adults appear to migrate to slightly shallower, warmer water when it’s time to mate and search for egg-laying sites. After hatching, juveniles gradually shift to deeper water as they mature.
Population Size and Threats
Nautilus populations are sparse even in healthy habitats. Surveys at Osprey Reef in Australia’s Coral Sea found the area “sparsely populated” compared to other known sites. Populations skew heavily male, with males making up about 83% of captured individuals across studies in the Philippines, Palau, New Caledonia, and Papua New Guinea.
The Philippines fishery has seen catch rates drop by roughly 80% over 10 to 20 years, even with only a few local fishermen working each site. Nautiluses grow slowly, reproduce late in life, produce few offspring, and don’t travel far. That combination of traits makes them extremely vulnerable to even modest fishing pressure. The primary driver is demand for their shells, which are sold as souvenirs, used in jewelry, and turned into decorative inlay. This trade has no cultural or historical basis in the communities where fishing occurs.
The entire nautilus family was added to CITES Appendix II in 2016, meaning international trade now requires permits and proof of sustainability. The chambered nautilus is also listed as threatened under the U.S. Endangered Species Act. Indonesia, the Philippines, and China have been flagged for continued trade despite restrictions.