The nautilus is a living relic, defying the short lives of its cephalopod cousins.

Nature · Published 3 October 2026 Swipe more like this →

In short: While most cephalopods live fast and die young, the nautilus is a remarkable exception. These ancient creatures, which have survived for millions of years, can live up to 15 years. Unlike their octopus and squid relatives, they possess a unique, chambered shell and a surprisingly high number of tentacles.

Nautiloids represent a fascinating lineage within the cephalopod class, a group that includes octopuses, squid, and cuttlefish. While modern cephalopods are often characterized by their intelligence, three hearts, and rapid growth rates—sometimes increasing body weight by 10% daily—nautiluses stand apart. Most cephalopods have incredibly short life spans, typically living only one to two years and spawning just once before dying. In stark contrast, the nautilus can survive for up to 15 years, making it a long-lived outlier in a group defined by fleeting existence.

The anatomy of the nautilus is equally distinct. While an octopus has eight arms and a squid has eight arms plus two tentacles, the nautilus boasts about 90 tentacles. These appendages lack the suckers found on the arms of octopuses, which use their suckers to hunt, capture prey, and manipulate objects. Furthermore, while many cephalopods rely on complex color-changing cells called iridophores to disguise themselves or communicate, the nautilus remains a unique study in evolutionary persistence. Its external shell, divided into internal chambers, provides a protective structure that has remained largely unchanged for eons.

Taxonomically, the nautiloid group is complex. It includes a few living species alongside thousands of fossilized forms that once dominated ancient oceans. Scientists classify these animals based on features like the siphuncle—a tube running through the shell chambers—and the simple, curved walls called septa that separate these chambers. Because nautiloids are a paraphyletic group, they are often viewed as the ancestral stock from which other cephalopod lineages diverged. Understanding these creatures provides a window into the deep history of marine life, offering a stark contrast to the highly derived, short-lived cephalopods that populate our modern seas.

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