The chambered nautilus (Allonautilus and Nautilus species) is the only living descendent of a group of ocean creatures that thrived in the seas 500 million years ago when the earth’s continents were still forming. It is even older than the dinosaurs! Chambered nautili are known as living fossils because they have remained virtually unchanged for millions of years.


Credit: USFWS

Among the last representatives of the ancient lineages of cephalopods (animals with no backbones but with tentacles or arms), chambered nautiluses are easily distinguished from their closest living relatives -- the octopus, squid, and cuttlefish -- by their distinctive external coiled shells. A feat in molluscan evolution, the internal chambers of their shell provide a buoyancy mechanism to facilitate movement that inspired the inventor of the earliest modern submarine to name the invention “Nautilus.”

They are found in the coastal reefs around Southeast Asia and Australia, including American Samoa. Chambered nautiluses grow slowly, maturing around 10-15 years of age. They produce a small number of eggs that require at least a year-long incubation period. These deep-sea scavengers spend much of their time hovering along the reef at depths of 100-300 meters (330-990 feet), dangling their tentacles as they move along in search of food. They have up to 90 retractable, suckerless tentacles with grooves that secrete mucous to help in obtaining food and attaching to the reef face when resting.

Research scientists have had little success breeding these animals in captivity; eggs will hatch but the young do not live long enough to reach maturity. Little is known about nautilus populations in the wild. The very first population estimate was made only in 2010.

Conserving the Chambered Nautilus

Harvested primarily for their beautiful shells, and not as a source of food, chambered nautiluses are sold as souvenirs to tourists and shell collectors, and as jewelry and home decoration items. Living animals are taken for public aquariums and research. The reef habitat where they live is also subject to pollution, destruction, and degradation and coral reefs are prone to being overfished for a variety of reef species that live there.

Yet, chambered nautilus biology does not lend itself to recovering from overfishing or adjusting to habitat destruction. These are slow-growing marine invertebrates – they take 15-20 years to reach maturity. They alsolay only one egg at a time and they produce a small number of eggs annually that take about 1 year to incubate that swim along the ocean reef. They do not swim in the open ocean and cannot move between habitats that are separated by deep ocean.

Due to their life history characteristics, chambered nautilus are currently vulnerable to trade and are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), effective January 2, 2017
For more information, see our spotlight on these species.

Additional Information

Save the Nautilus is an organization, started by some inspiring young conservationists, that is dedicated to raising awareness about the chambered nautilus and its conservation. Their informative website can be accessed here. Also be sure to check out an article featured in TIME For Kids on one child’s efforts to conserve this amazing creature.