Nautilus

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Nautilus

Nautilus (from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
?a?t????, 'sailor') is the common name of any marine creatures of the cephalopod

Cephalopod

The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
family Nautilidae, the sole family of the suborder Nautilina. It comprises six species in two genera, the type

Type genus

In biology, the phrase type genus is used differently depending on the nomenclature Codes that applies:* In ICZN, a type genus is "The nominal genus that is the name-bearing Biological type of a nominal family-group taxon."...
of which is the genus Nautilus
Nautilus (genus)

Nautilus is a genus of cephalopods in the family Nautilus. Species in this genus differ significantly in terms of morphology from those placed in the sister taxon Allonautilus....
. Though it more specifically refers to the species Nautilus pompilius, the name chambered nautilus

Chambered Nautilus

The Chambered Nautilus is the best known species of nautilus. The shell, when cut away as in the photograph in the gallery below, reveals a lining of lustrous nacre, and displays a nearly perfect logarithmic spiral....
is also used for any species of the Nautilidae.

Having survived relatively unchanged for millions of years, nautiluses represent the only living members of the subclass Nautiloidea, and are often considered to be "living fossil

Living fossil

Living fossil is an informal term for any living species of organism which appears to be the same as a species otherwise only known from fossils and which has no close living relatives....
s."

The name "Nautilus" originally referred to the Argonauta, otherwise known as paper nautiluses, because they allegedly use their two expanded arms as sails (cf.

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Encyclopedia

Nautilus (from Greek

Greek language

Cephalopod

Type genus

Chambered Nautilus

Living fossil

Aristotle

Aristotle was a Greeks philosopher, a student of Plato and teacher of Alexander the Great. He wrote on many subjects, including physics, metaphysics, Poetics , theater, music, logic, rhetoric, politics, government, ethics, biology and zoology....
Historia Animalium
History of Animals

History of Animals is a zoology natural history text by Aristotle.The work consists of lengthy descriptions of countless species of fish, shellfish, and other animals and their anatomies....
622b).

Description

The nautilus is similar in general form to other cephalopods, with a prominent head and tentacle

Tentacle

Tentacles can refer to the elongated flexible organs that are present in some animals, especially invertebrates, and sometimes to the hairs of the leaves of some carnivorous plant....
s. Nautiluses typically have more tentacles than other cephalopods, up to ninety. These tentacles are arranged into two circles and, unlike the tentacles of other cephalopods, they have no sucker

Sucker

Sucker may refer to:* Lollipop or sucker, a type of confection* Basal shoot or sucker, a shoot or cane that grows from the base of a tree or shrub...
s, are undifferentiated and retractable. The radula

Radula

The radula is an anatomical structure found in mollusks and used for feeding. It is a minutely toothed, chitinous ribbon. It is typically used for scraping or cutting food before the food enters the esophagus....
is wide and distinctively has nine teeth. There are two pairs of gill

Gill

A gill is an anatomical structure found in many aquatic ecosystem organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide....
s.

Nautilus pompilius is the largest species in the genus. One form from western Australia

Australia

Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
may reach 26.8 cm in diameter. However, most other nautilus species never exceed 20 cm. Nautilus macromphalus
Bellybutton Nautilus

The Bellybutton Nautilus is a species of nautilus native to the waters off New Caledonia, the Loyalty Islands, and northeastern Australia. The shell of this species lacks a Callus , leaving the umbilicus exposed, in which the inner coils of the shell are visible....
is the smallest species, usually measuring only 16 cm.

The shell

Nautiluses are the sole cephalopods whose bony structure of the body is externalized as a shell. The animal can withdraw completely into its shell, closing the opening with a leathery hood formed from two specially folded tentacle

Tentacle

Tentacles can refer to the elongated flexible organs that are present in some animals, especially invertebrates, and sometimes to the hairs of the leaves of some carnivorous plant....
s. The shell is coiled, calcareous, nacreous and pressure resistant (imploding at a depth of about 800 m). The nautilus shell is composed of 2 layers: the outer layer is a matte

Matte

Matte may refer to:In film:* Matte , film and video technology* Matte painting, a process of creating sets used in film and video* Matte box, a camera accessory for controlling lens glare...
white, while the inner layer is a striking white with iridescence

Iridescence

Iridescence is an optical phenomenon in which hue changes with the angle from which a surface is viewed. Iridescence may be easily seen in soap bubbles and butterfly wings....
. The innermost portion of the shell is a pearlescent blue-gray. The osmena pearl, contrarily to its name, is not a pearl

Pearl

A pearl is a hard, roundish object produced within the soft tissue of a living animal shelled mollusk. Just like the shell of mollusks, a pearl is made up of of calcium carbonate in minute crystalline form, which has been deposited in concentric layers....
, but a jewelry product derived from this part of the shell.

The shell is internally divided into chambers, the chambered section being called the phragmocone

Phragmocone

The phragmocone is the chambered portion of the Animal shell of a cephalopod. It is divided by Septa into camerae.In most nautiloids and Ammonoideas, the phragmocone is a long, straight, curved, or coiled structure, in which the camarae are linked by a siphuncle which determines buoyancy by means of gas exchange....
. The phragmocone is divided into camerae

Camerae

Camerae are the spaces or chambers enclosed between two adjacent Septa in the phragmocone of a nautiloid or Ammonoidea cephalopod. These can be seen in cross-sections of a nautilus shell and in the polished cross-sections of ammonites....
by septa

Septa (biology)

Septa are thin walls or partitions between the internal chambers of the Animal shell of a cephalopod, namely nautiloids or Ammonoideas.As the creature grows, its body moves forward in the shell to a new living chamber, secreting septa behind it....
, all of which are pierced in the middle by a duct, the siphuncle

Siphuncle

The siphuncle is a strand of biological tissue passing longitudinally through the mollusc shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula....
. As the nautilus matures its body moves forward, sealing the camerae behind it with a new septum. The last fully open chamber, also the largest one, is used as the living chamber. The number of camerae increases from around four at the moment of hatching

Hatching

Hatching is an artistic technique used to create tonal or shading effects by drawing closely spaced parallel lines. When lines are placed at an angle to one another, it is called cross-hatching....
to thirty or more in adults.

The shell coloration also keeps the animal cryptic in the water. When seen from the top, the shell is darker in color and marked with irregular stripes, which makes it blend into the darkness of the water below. On the contrary, the underside is almost completely white, making the animal indistinguishable from brighter waters near the ocean surface. This mode of camouflage

Camouflage

Camouflage is a method of cryptic or concealing coloration that allows an otherwise visible organism or object to remain invisibility through deception....
is named countershading

Countershading

Countershading, or Thayer?s Law, is a form of camouflage. Countershading, in which an animal?s pigmentation is darker dorsum , is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal?s body....
.

The nautilus shell presents one of the finest natural examples of a logarithmic spiral

Logarithmic spiral

A logarithmic spiral, equiangular spiral or growth spiral is a special kind of spiral curve which often appears in nature. The logarithmic spiral was first described by Ren? Descartes and later extensively investigated by Jakob Bernoulli, who called it Spira mirabilis, "the marvelous spiral"....
, although it is not a golden spiral

Golden spiral

In geometry, a golden spiral is a logarithmic spiral whose growth factor b is related to φ, the golden ratio. Specifically, a golden spiral gets wider by a factor of φ for every quarter turn it makes....
.

Buoyancy and movement

In order to swim, the nautilus draws water into and out of the living chamber with the hyponome

Hyponome

A siphon is an anatomical structure which is part of the soft parts of aquatic molluscs in three Class es: Gastropoda, Bivalvia and Cephalopoda....
, which makes use of jet propulsion. When water is inside the chamber, the siphuncle

Siphuncle

Salt

A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and base . Salts are ionic compounds composed of cations and anions so that the product is electrically electric charge ....
from it and diffuses it into the blood. When water is pumped out, the animal adjusts its buoyancy

Buoyancy

In physics, buoyancy is the upward force that keeps things afloat. The net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body....
with the gas contained in the chamber. Buoyancy can be controlled by the osmotical

Osmosis

Osmosis is the diffusion of a solvent through a Semipermeable membrane, from a solution of low solute concentration to a solution with high solute concentration , up a solute concentration gradient....
pumping of gas and fluid into or from the camerae along the siphuncles. The control of buoyancy in this manner limits the nautilus; they cannot operate under extreme hydrostatic pressures.

In the wild, nautiluses usually inhabit depths of about 300 m, rising to around 100 m at night for feeding, mating and egg

Egg (biology)

In most birds and reptiles, an egg is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo....
laying. The shell of the nautilus cannot withstand depths greater than approximately 800 m.

Diet and sensory system

Nautiluses are predators and feed mainly on shrimp

Shrimp

Shrimp are swimming, Decapoda crustaceans classified in the infraorder Caridea, found widely around the world in both fresh water and seawater. Adult shrimp are Filter feeder benthic animals living close to the bottom....
, small fish

Fish

A fish is any marine biology vertebrate animal that is typically ectothermic , covered with scale , and equipped with two sets of paired fins and several unpaired fins....
and crustacean

Crustacean

Crustaceans are a large group of arthropods, comprising almost 52,000 described species , and are usually treated as a subphylum . They include various familiar animals, such as crabs, lobsters, crayfish, shrimp, krill and barnacles....
s, which are captured by the tentacles. Due to the limited energy expended in swimming, they need only eat once a month. Unlike many other cephalopods, they do not have good vision; their eye structure is highly developed but lacks a solid lens

Lens (anatomy)

The lens is a transparent, Lens_#Types_of_lenses structure in the eye that, along with the cornea, helps to refract light to be Focus on the retina....
. They have a simple "pinhole

Pinhole camera

A pinhole camera is a very simple camera with no photographic lens and a single very small aperture. Simply explained, it is a light-proof box with a small hole in one side....
" lens through which water can pass. Instead of vision, the animal is thought to use olfaction

Olfaction

Olfaction refers to the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates....
as the primary sense for foraging

Foraging

Foraging theory is a branch of behavioral ecology that studies the foraging behavior of animals in response to the environment in which the animal lives....
, locating or identifying potential mates.

Reproduction and lifespan

Nautiluses are sexually dimorphic

Sexual dimorphism

Sexual dimorphism is the systematic difference in form between individuals of different sex in the same species. Examples include color , size, and the presence or absence of parts of the body used in courtship displays or fights, such as ornamental feathers, horns, antlers or tusks....
, in that males have four tentacles modified into an organ, called the "spadix," which transfers sperm into the female's mantle during mating. Nautiluses reproduce by laying egg

Egg (biology)

In most birds and reptiles, an egg is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo....
s. Gravid females attach the fertilized eggs to rocks in shallow waters, whereupon the eggs take eight to twelve months to develop until the 30 mm juveniles hatch. Females spawn once per year and regenerate their gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells....
s, making nautiluses the only cephalopods to present iteroparity or polycyclic spawning. The lifespan of nautiluses is about 20 years, which is exceptionally long for a cephalopod.

Classification

The genus Nautilus contains six extant species and several extinct species

Extinct species

This page features extinct species, organisms that have become Extinction.* List of extinct animals* List of extinct plants...
.

Genus Allonautilus
Allonautilus

The genus Allonautilus contains two species of nautiluses, which differ significantly in terms of morphology from those placed in the sister taxon Nautilus ....

Allonautilus perforatus
Allonautilus perforatus

Allonautilus perforatus is a species of nautilus native to the waters around Bali, Indonesia. It is known only from drifted shells and, as such, is the least studied of the six recognised nautilus species....
Allonautilus scrobiculatus
Crusty Nautilus

The Crusty Nautilus is a species of nautilus native to the waters around New Guinea, specifically New Britain and Milne Bay, and the Solomon Islands....

Genus Nautilus
Nautilus (genus)

Nautilus is a genus of cephalopods in the family Nautilus. Species in this genus differ significantly in terms of morphology from those placed in the sister taxon Allonautilus....

Nautilus belauensis
Palau Nautilus

The Palau Nautilus is a species of nautilus native to the waters around the Pacific Ocean island nation of Palau. N. belauensis is very similar to Chambered Nautilus and shares with this species a closed umbilicus covered with a callus ....
†Nautilus clarkanus
Nautilus clarkanus

Nautilus clarkanus is an extinction species of nautilus. It lived during the Lower Carboniferous. Fossil specimens have been uncovered in the Spergen Hill Limestone formation of Indiana....
†Nautilus cookanum
Nautilus cookanum

Nautilus cookanum is an extinction species of nautilus. It lived during the Eocene epoch. N. cookanum has been grouped into a single taxon together with extant species based on their shared shell characters....
Nautilus macromphalus
Bellybutton Nautilus

The Bellybutton Nautilus is a species of nautilus native to the waters off New Caledonia, the Loyalty Islands, and northeastern Australia. The shell of this species lacks a Callus , leaving the umbilicus exposed, in which the inner coils of the shell are visible....
Nautilus pompilius (type
Type species

In taxonomy, a type species is the species that originally defined a genus . It is an individual specimen that fixes the name of a genus . Two different definitions are used interchangeably, in a general term and a botanical term....
)

Nautilus pompilius pompilius
Nautilus pompilius suluensis

†Nautilus praepompilius
Nautilus praepompilius

Nautilus praepompilius is an extinction species of nautilus. It lived during the late Eocene and Oligocene epochs. Fossil specimens have been uncovered from the Chegan Formation of Kazakhstan....
Nautilus stenomphalus
White-patch Nautilus

The White-patch Nautilus is a species of nautilus native to the Great Barrier Reef. N. stenomphalus is very similar to Chambered Nautilus and may in fact represent a subspecies....

Dubious or uncertain taxa

The following taxa

Taxon

A taxon or taxonomic unit is a name designating an organism or a group of organisms. In biological nomenclature according to Carl Linnaeus, a taxon is assigned a taxonomic rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships....
associated with the family Nautilidae are of uncertain taxonomic status:

Binomial name and author citation	Current systematic status	Type locality	Type repository
Nautilus alumnus Iredale Tom Iredale Tom Iredale was an England-born ornithologist and malacologist born at Stainburn, Workington, Cumberland, who had a long association with Australia where he lived for most of his life.... , 1944	Species dubium [fide Saunders (1987:49)]	Queensland Queensland Queensland is a States and territories of Australia of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south.... , Australia Australia Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....	Not designated [fide Saunders (1987:49)]
Nautilus ambiguus Sowerby, 1848	Species dubium [fide Saunders (1987:48)]	Not designated	Unresolved
Nautilus beccarii Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Non-cephalopod; Foraminifera Foraminifera The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net.... [fide Frizzell and Keen (1949:106)]
Nautilus calcar Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	?Non-cephalopod; Foraminifera Lenticulina	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus crispus Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Mediterranean Sea Mediterranean Sea The Mediterranean Sea is a sea or Ocean off the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus crista Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Non-cephalopod; Turbo [fide Dodge (1953:14)]
Nautilus fascia Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus granum Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Mediterranean Sea Mediterranean Sea The Mediterranean Sea is a sea or Ocean off the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus lacustris Lightfoot John Lightfoot FRS The Reverend John Lightfoot was an England conchologist and botanist.Lightfoot was the chaplain and librarian of Margaret Bentinck, Duchess of Portland.... , 1786	Non-cephalopod; Helix Helix (genus) *Helix* is a genus of large air-breathing land snails, terrestrial Pulmonata gastropod molluscs. This genus is native to Europe and the regions around the Mediterranean Sea.... [fide Dillwyn Lewis Weston Dillwyn Lewis Weston Dillwyn , eldest son of William Dillwyn and Sarah Dillwyn , was born in Walthamstow. His father, a Pennsylvanian Quaker had returned to Britain in 1777 during Philadelphia's worst period in the American War of Independence and settled at Higham Lodge, Walthamstow, Essex, UK.... (1817:339)]
Nautilus legumen Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus micrombilicatus Joubin, 1888	Nomen nudum Nomen nudum The phrase *nomen nudum* is a Latin language term, meaning "naked name". In taxonomy, this is used to indicate a term or phrase which looks like a scientific name, and may well have been intended to become a scientific name, but fails to be one because it was not published with an adequate description , and thus is "bare" or "naked"....
Nautilus obliquus Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus pompilius marginalis Willey, 1896	Species dubium [fide Saunders (1987:50)]	New Guinea New Guinea New Guinea, located just north of Australia, is the List of islands by area, having become separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period....	Unresolved
Nautilus pompilius moretoni Willey, 1896	Species dubium [fide Saunders (1987:49)]	New Guinea New Guinea New Guinea, located just north of Australia, is the List of islands by area, having become separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period....	Unresolved
Nautilus pompilius perforatus Willey, 1896	Species dubium [fide Saunders (1987:49)]	New Guinea New Guinea New Guinea, located just north of Australia, is the List of islands by area, having become separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period....	Unresolved
Nautilus radicula Linne, 1758	?Non-cephalopod; Foraminifera Nodosaria	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus raphanistrum Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Mediterranean Sea Mediterranean Sea The Mediterranean Sea is a sea or Ocean off the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus raphanus Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758]]	Undetermined	Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus semi-lituus Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	Liburni, Adriatic Sea Adriatic Sea The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus sipunculus Linne Linne Linne is a town in the Netherlands province of Limburg . It is a part of the municipality of Maasgouw, and lies about 6 km southwest of Roermond.... , 1758	Undetermined	"freto Siculo"	Unresolved; Linnean Society of London Linnean Society of London The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals.... ?
Nautilus texturatus Gould, 1857	Nomen nudum Nomen nudum The phrase *nomen nudum* is a Latin language term, meaning "naked name". In taxonomy, this is used to indicate a term or phrase which looks like a scientific name, and may well have been intended to become a scientific name, but fails to be one because it was not published with an adequate description , and thus is "bare" or "naked"....
Octopodia nautilus Schneider, 1784	Rejected specific name [fide Opinion 233, ICZN (1954:278)]

Distribution

Nautiluses are only found in the Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeography region of the earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia....
, from 30° N to 30° S latitude and 90° to 185° W longitude. They inhabit the deep slopes of coral reef

Coral reef

Coral reefs are aragonite structures produced by living organisms. In most reefs the predominant organisms are colonial cnidarian that secrete an exoskeleton of calcium carbonate....
s.

Natural history

Fossil

Fossils are the preserved remains or trace fossil of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous Rock formations and sedimentary rock layers is known as the fossil record....
records indicate that nautiluses have not evolved much during the last 500 million years, and nautiloids were much more extensive and varied 200 million years ago. Many were initially straight-shelled, as in the extinct genus Lituites
Lituites

Lituites is an extinct genus of the nautiloids, and is one of the most primitive known cephalopods. It originated in the Ordovician period, around 460 million years ago....
. They developed in the Cambrian

Cambrian

The Cambrian is a geologic period that began about Mya at the end of the Proterozoic eon and ended about Ma with the beginning of the Ordovician period ....
period and became a significant sea predator in the Ordovician

Ordovician

The Ordovician is a geologic period, the second of six of the Paleozoic era , and covers the time between 488.3?1.7 to 443.7?1.5 million years ago ....
period. Certain species reached over 2.5 meters in size. The other cephalopod subclass, Coleoidea

Coleoidea

Subclass Coleoidea is the grouping of cephalopods containing all the primarily soft-bodied creatures. Unlike its sister group the Nautiloidea, which has a rigid outer shell for protection, the coleoids have at most an internal bone or shell that is used for buoyancy or support....
, diverged from the Nautilidae long ago and the nautilus has remained relatively unchanged since. Extinct

Extinction

In biology and ecology, extinction is the death of every member of a species or group of taxon. The moment of extinction is generally considered to be the death of the last individual of that species ....
relatives of the nautilus include ammonite

Ammonite

Ammonites are an Extinction group of marine animals of the Subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific Geologic time scale....
s, such as the baculite

Baculite

Baculites is a genus of Extinction marine animals in the phylum Mollusca and class Cephalopoda. They are a nearly straight-shelled type of heteromorph ammonite that lived worldwide throughout the Late Cretaceous period....
s and goniatites

Goniatites

Goniatites is genus of the Goniatitaceae superfamily. They are an extinction group of ammonite, which are shelled cephalopods related to squids, belemnites, octopus, and cuttlefish, and more distantly to the nautiloids....
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Nautilus

Description

The shell

Buoyancy and movement

Diet and sensory system

Reproduction and lifespan

Classification

Dubious or uncertain taxa

Distribution

Natural history

See also

External links