10 Types of Nautiloids: Meet the Living Species of Nautilus and Allonautilus

Fossil hunters have catalogued more than 2,500 nautiloid species from rock layers spanning nearly half a billion years, yet only a small cluster of coiled-shell survivors remains in today’s oceans. Understanding the types of nautiloids alive now means sorting through a genus list that has been revised repeatedly as DNA evidence catches up with century-old shell descriptions. Some of these animals were only given scientific names in 2023, while others have been argued over for decades.

This piece walks through the ten Nautilus and Allonautilus species that researchers currently recognize or have proposed, covering where each one lives, what sets its shell apart, and why its taxonomic status is or isn’t settled. Along the way, the deeper story of these animals’ predatory instincts in wildlife and their precarious survival behaviors in a shrinking Pacific range comes into focus.

1. Nautilus Pompilius

The chambered nautilus, Nautilus pompilius, is the type species of the entire genus and the one most people picture when they hear the word “nautilus.” Linnaeus described it in 1758, and it remains the most geographically widespread of the living nautiloids, ranging across much of the Indo-Pacific from the Andaman Sea to Fiji and northern Australia.

Adults commonly reach shell diameters around 8 inches, with the spiral shell housing a soft-bodied animal that uses buoyancy chambers rather than fins or jet propulsion alone to manage its depth. A recognized subspecies, N. p. suluensis, occurs in the Philippines, though genome-wide studies have struggled to separate it cleanly from the broader population.

This is also the species that illustrates nature’s harsher realities most starkly. Research on the species’ phylogeography notes that N. pompilius is fished for its shell more heavily in the Philippines than anywhere else, with little monitoring of the harvest. A CITES proposal documenting the trade found that trap yields in the Tañon Strait fishery fell by 97 percent, and researchers consider the local population commercially extinct there.

Important Note: Nautilus shell harvesting data referenced here comes from a CITES proposal compiled in the mid-2010s. Regional fishery pressure and regulations may have shifted since that assessment, so readers researching current trade rules should check the latest CITES appendices directly.

2. Nautilus Belauensis

The Palau nautilus, Nautilus belauensis, is endemic to the waters around Palau in the western Pacific. It was described by Saunders in 1981 on the strength of shell and soft-tissue differences that seemed, at the time, distinct enough to warrant a separate species.

That separation has not held up well under scrutiny. Recent taxonomic review notes that N. belauensis has been disputed and is not currently supported by phylogenetic studies, since it does not show significant morphological differences from other extant species. Some researchers have treated it as a junior synonym of N. pompilius, though the name is still accepted as valid elsewhere.

3. Nautilus Macromphalus

Commonly called the bellybutton nautilus for the pronounced umbilical depression at the center of its shell coil, Nautilus macromphalus is restricted to the waters off New Caledonia. Where the chambered nautilus ranges across the wider Indo-Pacific, this species effectively replaces it in that one archipelago.

The FAO species catalogue for commercial cephalopods notes that N. pompilius is absent from around New Caledonia, where it is replaced by Nautilus macromphalus. That kind of geographic exclusivity, repeated across several of the species on this list, is part of why researchers increasingly treat depth and distance as real barriers separating nautilus populations rather than minor regional quirks.

4. Nautilus Stenomphalus

The white-patch nautilus, Nautilus stenomphalus, takes its common name from a pale marking near the umbilicus that is absent on most other species. It occurs off northern Australia and is sympatric with both N. pompilius and Allonautilus scrobiculatus in parts of its range.

Like several entries on this list, its species status is genuinely contested among biologists. A 2016 mitochondrial study examining the hypothesis that multiple named species are actually one animal with variable shell traits found that the validity of N. stenomphalus, alongside N. repertus and N. belauensis, has been questioned in the taxonomic literature. The same paper found that nautiluses sampled from the Philippines, eastern Australia, Vanuatu, American Samoa, and Fiji fell into distinct geographic genetic clades, which is part of the evidence that eventually supported naming three brand-new species in 2023.

5. Nautilus Repertus

The Australian pearly nautilus, Nautilus repertus, was first described by Iredale in 1944 from specimens collected at Rottnest Island and Pelsaert Island off Western Australia. The species is reported from both Western Australia and the Philippines, with mature shells reaching up to 228 millimeters in diameter, living close to the seafloor over reef slopes from near the surface down to roughly 500 meters.

Its taxonomic fate illustrates just how unsettled nautilus classification remains. The World Register of Marine Species currently lists N. repertus as a taxon inquirendum, meaning its status needs further investigation, while a separate taxonomic summary for the genus describes it as a likely nomen dubium, possibly representing nothing more than a giant form of N. pompilius. Genetic work has also linked the name with N. belauensis rather than treating it as fully distinct, which is a reminder that shell size and shape alone rarely settle these debates.

6. Nautilus Samoaensis

Named only in 2023, the Samoan nautilus, Nautilus samoaensis, was described from specimens collected around American Samoa. It is one of three new Nautilus species formally named using a combination of shell measurements, soft-anatomy observations, and genetic sequencing rather than shell shape alone.

The researchers behind the description argued that naming the species was overdue given new findings on genetic structure, geographic occurrence, and morphological traits such as color patterns of the shell and hood. Because nautilus populations separated by deep water rarely mix, American Samoa’s isolated location gives this species a genuinely distinct identity rather than being just a regional variant of a wider-ranging animal.

7. Nautilus Vanuatuensis

The Vanuatu nautilus, Nautilus vanuatuensis, is the second of the three species named in the 2023 Coral Sea and South Pacific revision. Its description relied on the same genetic and morphological evidence used for its Samoan and Fijian relatives, reflecting a broader pattern across this part of the Pacific where island groups separated by deep channels have each developed their own distinct nautilus population.

Depth itself functions as the barrier that keeps these island populations apart. Nautilid shells implode at depths greater than 800 meters, so stretches of ocean deeper than that, combined with horizontal separations of 200 kilometers or more between island groups, prevent gene flow between populations almost as effectively as a wall would. That isolation is precisely what let N. vanuatuensis diverge enough to earn its own name.

8. Nautilus Vitiensis

Rounding out the trio of 2023 species, the Fiji nautilus, Nautilus vitiensis, was described from populations around Fiji. Like its Samoan and Vanuatu counterparts, its recognition depended on genetic structure data that revealed a geographically distinct clade rather than relying solely on traditional shell-based classification.

The research team that named all three species noted that formal recognition would aid conservation management of what they describe as possibly endangered animals, since each island population is naturally small, isolated, and vulnerable to even modest fishing pressure. For readers interested in how isolated or small populations get flagged for protection more broadly, resources cataloguing endangered animals in other Pacific-adjacent regions illustrate similar documentation challenges.

9. Allonautilus Scrobiculatus

The crusty nautilus, Allonautilus scrobiculatus, belongs to a different genus entirely and looks it. This is the type species of Allonautilus, a genus whose members have a significantly different morphology from species placed in the sister genus Nautilus, including a fuzzy, hair-like periostracum coating much of the shell and a distinctly different gill and reproductive anatomy.

Genetic comparisons back up what the shell differences suggested. Mitogenome studies comparing Allonautilus and Nautilus confirm that their split represents the oldest divergence among living nautiloids, which is why taxonomists eventually moved this species out of Nautilus altogether rather than treating it as an unusual variant. It occurs off New Guinea, overlapping in range with both N. pompilius and N. stenomphalus in the same reef slope habitats.

Key Insight: The split between Nautilus and Allonautilus is older than the split between some of the individually named Nautilus species, which is why a handful of disputed species names (belauensis, stenomphalus, repertus) keep resurfacing in taxonomic revisions while the genus-level divide has stayed stable.

10. Allonautilus Perforatus

The second and far less documented species in the genus, the Bali nautilus, was originally described as Nautilus perforatus before researchers reclassified it as Allonautilus perforatus once its closer relationship to the crusty nautilus became clear. A Wikipedia summary of nautilus taxonomy confirms this history, noting that the original name was reclassified as Allonautilus perforatus after further study.

Records of this species are sparse compared with every other animal on this list. It is associated with waters around Indonesia, including the Bali region, but detailed population studies and recent sighting data are limited, which keeps it one of the least-understood living cephalopods despite belonging to a genus that otherwise attracts significant research attention.

Across all ten names, the pattern that emerges is less about counting discrete species and more about watching taxonomy catch up with genetics in real time. A few names, like N. repertus and N. belauensis, may eventually collapse into N. pompilius as more sequencing data accumulates. Others, like the three 2023 South Pacific species, show that isolated island populations separated by deep-water barriers can accumulate enough genetic and morphological difference to justify entirely new names.

What hasn’t changed is the vulnerability shared by every one of these animals. Small, slow-breeding, geographically confined populations living on narrow reef slopes make nautiluses easy to overharvest and slow to recover, a dynamic that mirrors the population mixing and boundary questions biologists grapple with when population genetics blurs the line between what counts as one species or several. Whether the final tally of living nautiloid types settles at six, seven, or ten, the animals themselves remain among the ocean’s most fragile living links to a 500-million-year lineage.