NAUTILUS SHELLS

Nautilus Shells

The Nautilus genus, a marine cephalopod within the Nautilidae mollusk family, exhibits significant morphological differences from the two species classified under the closely related sister-taxon Allonautilus.

A cephalopod is a member of the molluscan class Cephalopoda, which includes species such as squids, octopuses, cuttlefish, and nautiluses. These marine animals are distinguished by their bilateral body symmetry, distinct heads, and a series of arms or tentacles, which are muscular hydrostats evolved from the primitive molluscan foot. Fishermen often refer to cephalopods as "inkfish," alluding to their shared trait of ejecting ink. This ink typically appears as a dark patch on the shell.

The classification of species within the genus Nautilus has been a subject of debate for decades, leading to multiple reconfigurations and redefinitions over time. Nautilus, the type genus of the Nautilidae family, was initially defined as any species with a coiled shell and simple sutures—walls between shell compartments. Species with complex sutures were categorized under the genus Ammonites. This classification stood for nearly two centuries, from the genus's establishment in 1758 by Carl Linnaeus until 1949. That year, paleobiologist Arthur K. Miller provided a comprehensive description of the N. pompilius shell, designating it as the type species for the genus. In 1951, Miller proposed that only living Nautilus species should be included in the genus, a significant shift from the previous inclusion of numerous fossil species.

Species of the genus Nautilus are found in the Indo-Pacific, particularly in the tropical waters of this region, though their full geographic range remains undocumented. The depth of water significantly limits the movement of Nautilus species. They struggle to traverse areas deeper than 27 feet, with most of their activity taking place between 330 and 985 feet deep. Occasionally, Nautilus may be spotted shallower than 328 feet, but the shallowest depth they inhabit is influenced by factors like water temperature and seasonality. All species of Nautilus are considered likely endangered, as evidenced by the overfishing of Nautilus Pompilius in the Philippines, leading to an 80% population reduction from 1980 to 2010.

Nautiluses have been observed spending days in the deeper regions around coral reefs to evade predators such as turtles and carnivorous fish, and they ascend to the reef's shallow areas at night. In these shallower waters, they scavenge for animal remains and crustacean molts. Typically, nautiluses are solitary in their travels and feeding habits. After daybreak, they return to the depths where they also lay their eggs, which take about a year to hatch. This behavioral pattern may have contributed to their survival during the Cretaceous-Paleogene extinction event, which rendered shallow oceanic areas uninhabitable. Nautiluses are known to inhabit a wide range of depths, up to approximately 1640 feet, but are at risk of implosion if they exceed their depth and pressure thresholds. The shells of living nautiluses can collapse at depths exceeding 2460 feet, depending on the species.

The feeding behavior of the genus has been determined through observations of captive individuals and analysis of the stomach contents of wild specimens. Nautilus are opportunistic feeders, consuming a variety of crustaceans, including their sheds, and fish, but they have also been known to eat chicken and bat bait. While Nautilus were once believed to be active predators of certain prey, this behavior has only been documented in traps, where prey is confined close to the Nautilus. They locate food using their tentacles, which possess chemosensory abilities, and their vision. Nautilus engage in regular vertical migrations, rising to shallow reef areas between 328 and 492 feet deep at night to feed, then descending to depths of 820 to 1148 feet during the day, although these depths can vary with local geography. Nautilus can ascend at roughly 7 feet per minute and descend at about 10 feet per minute.

Numerous species are known to prey on the Nautilus. Octopuses, for instance, have been identified as predators, especially after an event where an octopus was found having partially eaten a Nautilus in a trap. Moreover, many drift shells show small holes that correspond to the marks left by octopuses drilling into the shell to feed. Teleost fish, like triggerfish, are also known to consume Nautilus by forcefully ramming them to fracture their shells. When faced with predator attacks, Nautilus retreat into their shells for protection.

It is possible to keep Nautilus in aquaria, however, specific care is necessary in order to ensure their survival in captivity. The survival rate of Nautilus in captivity is relatively poor, primarily due to the stress that individuals are subjected to during transportation. As many as 50-80% of Nautilus die during transportation, and this percentage can be higher if individuals are exposed to high temperatures. In captivity, Nautilus are generally fed a diet of whole shrimp, fish, crab, and lobster moults. Several aquaria around the world host specimens of the genus, however, there have not yet been any successful attempts of breeding in captivity, despite viable eggs being produced at several locations. Two Nautilus eggs were hatched at Waikiki Aquarium, however, these individuals both died months later.

The majority of our knowledge about Nautilus reproduction is derived from captive individuals in aquariums. These observations suggest that Nautiluses lack a complex courtship ritual. Males are known to attempt mating with any object resembling another Nautilus in size and shape. Upon locating a female, the male engages in the mating process and may remain attached to the female for a duration varying from several minutes to hours.

Nautilus eggs are deposited in capsules that are typically 1 to 2 inches in length and gradually harden upon exposure to seawater. The exact method by which juveniles escape these capsules is not fully understood, but it is speculated that they may chew their way out using their beaks. The genus displays a sex ratio heavily skewed towards males, a pattern observed in various global locations, with some populations comprising up to 95% males. The cause of this imbalance remains a mystery.

The male nautilus possesses a reproductive organ called Van der Hoeven's organ. The female nautilus has two reproductive organs, the functions of which are not yet understood: the Organ of Valenciennes and Owen's laminated organ.

All nautilus species are threatened by overfishing for their shells, commonly used in jewelry and decorative crafts. In 2016, they were included in CITES Appendix II to restrict international trade, and the chambered nautilus was subsequently designated as a threatened species under the Endangered Species Act. Consequently, commercial harvesting of these species is prohibited. We possess a finite inventory acquired prior to their endangered classification. Availability following the sale of this stock is unpredictable.

Scientific classification

Domain: Eukaryota

Kingdom: Animalia

Phylum: Mollusca

Class: Cephalopoda

Subclass: Nautiloidea

Order: Nautilida

Family: Nautilidae

Genus: Nautilus

Linnaeus, 1758

(REF: "Checklist of CITES species".)(REF: Ward, Peter; Dooley, Frederick; Barord, Gregory Jeff (2016-02-29). "Nautilus: biology, systematics, and paleobiology as viewed from 2015". Swiss Journal of Palaeontology. 135)(REF: Goedert, James L.; Kiel, Steffen; Tsai, Cheng-Hsiu (2022). "Miocene Nautilus (Mollusca, Cephalopoda) from Taiwan, and a review of the Indo-Pacific fossil record of Nautilus)(REF:Gregory J. Barord, David J. Combosch, Gonzalo Giribet, Neil Landman, Sarah Lemer, Job Veloso et Peter D. Ward, « Three new species of Nautilus Linnaeus, 1758 (Mollusca, Cephalopoda) from the Coral Sea and South Pacific)(REF:Griffin, Lawrence E. (October 1897). "Notes on the Anatomy of Nautilus Pompilius". Zoological Bulletin. 1)(REF: Wray, Charles G.; Landman, Neil H.; Saunders, W. Bruce; Bonacum, James (1995). "Genetic divergence and geographic diversification in Nautilus". Paleobiology. 21)(reF: Barber, V. C.; Wright, D. E. (1969). "The fine structure of the sense organs of the cephalopod mollusc Nautilus". Zeitschrift für Zellforschung und Mikroskopische Anatomie. 102 )(REF: Dunstan, A.; Alanis, O.; Marshall, J. (November 2010). "Nautilus pompilius fishing and population decline in the Philippines: A comparison with an unexploited Australian Nautilus population". Fisheries Research. 106)(REF:Landman, Neil H.; Cochran, J. Kirk; Rye, Danny M.; Tanabe, Kazushige; Arnold, John M. (1994). "Early life history of Nautilus: evidence from isotopic analyses of aquarium-reared specimens". Paleobiology. 20 )(REF: Arthur Willey (1902). Zoological Results Based on Material from New Britain, New Guinea, Loyalty Islands and Elsewhere: The anatomy and development of Peripatus novae-britanniae. University Press. pp. 778–9.)

Whole Natural/Tiger Nautilus Shells

Our Nautilus shells are in their natural condition. We carefully inspect shells to make sure they are not broken prior to SHIPMENT. These are high quality shells

F5-5

A whole Tiger Nautilus shell, measuring at least five inches.. .....$115

F6-5

A whole Tiger Nautilus shell, measuring at least 6 inches.. ......$125

F7-5

A complete Nautilus shell, measuring at least 7 inches......$135

Contact shells-of-aquarius by email at ja1@mindspring.com

TIGER NAUTILUS CENTER CUT WITH TWO MATCHING PARTS

Tiger Nautilus Center Cut

The picture shows the Natural pearlized inner shell of the Tiger Nautilus. The bi and tri cut Nautilus shells are the best way to view the iridescent inner shell of the Natural Nautilus.

***OUR NAUTILUS SHELLS ARE IN THEIR NATURAL CONDITION. WE CAREFULLY INSPECT SHELLS TO MAKE SURE THEY ARE NOT BROKEN BEFORE SHIPMENT. THESE ARE HIGH QUALITY SHELLS

The picture shows the compartments of the Nautilus. This is where the Nautilus animal housed itself while the shell grew. Each compartment represents a growth period.

You can also see the Nautilus beak. The beak is different for every Nautilus. Notice the black coloration, this is the beak, where the animal lived. The color comes from a dye the animal releases.

TIGER NAUTILUS SHELL 3 SECTION CUT MATCHING SET

THREE SECTION TIGER NAUTILUS SHELL MATCHING SET

WHOLE PEARL NAUTILUS SHELL

Pearl Nautilus shell

These are actually a highly polished Tiger Nautilus shell. Artisans polish the Tiger Nautilus shell down to its iridescent inner shell or nacre; often called the "mother of pearl". Notice that the Tiger Nautilus is pearlized with the exception of the beak. As previously described, the beak is unique in all Nautilus shells. The beak is the area of black coloration near the shell opening. It is where the animal lived. While alive, the Nautilus animal excreted a black dye like liquid.

Tiger (natural Nautilus) shells are found mostly in the Indochina waters, running from the Indian Ocean East to the northern coast of Australia. They are free swimmers; using their chambered inner shell areas to hold a gas that keeps their buoyancy under conThe Pearl Nautilus shell is the Natural Nautilus or sometimes called the Chambered Nautilus or Tiger Nautilus. The Pearl Nautilus under goes intensive polishing until the inner shell or nacre appears. The nacre sometimes referred to as the "mother of pearl". You can see the pearlized effect in the picture. The Tiger Nautilus has this pearlization on the inner side of the shell.

The Center Cut Pearl Nautilus enables you to see the Nautilus chambers (where the animal lived during stages of its life). The chambers were gas filled, which helped the Nautilus control its buoyancy. The buoyant shell then was able swim freely with the ocean currents.

This is a lightweight thin-shelled species, coveted for its color. The pearlized Nautilus is especially sought by collectors and vacationers for its total pearlized look.

The Pearl Nautilus shell has the pearl effect over its entire body except for the beak. The beak is unique with all Nautilus shells. You will see the beak at the shell opening. The picture does not give a good example of the beak. The is composed of black discoloration. It is where the Nautilus animal last lived inside the shell (the final chamber). The beak color is from black/purple like dye the animal excretes. The beak is more pronounced in some Nautilus'.

The Nautilus is now mostly confined to the Indo-Pacific region.

WHOLE PEARL NAUTILUS

D2-5

One whole Pearl Nautilus shell, measuring at least 2 inches in size........ $25

D3-5

One Whole Pearl Nautilus, measuring at least 3 inches....... $35

D7-5

A single, whole Pearl Nautilus shell, measuring at least 7 inches...... $135

D5-5

A complete Pearl Nautilus shell, measuring at least 5 inches....... $110

D6-5

A complete Pearl Nautilus shell, measuring at least 6 inches........$125

PEARL NAUTILUS SHELL CUT INTO TWO MATCHING SECTIONS

PEARL NAUTILUS SHELL CENTER CUT

PEARL NAUTILUS SHELL 3 SECTION CUT MATCHING SET

PEARL NAUTILUS 3 SECTION CUT MATCHING SET

O4-6

A Pearl Nautilus shell, measuring at least 4 inches, sectioned into three parts....... $45