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Explorer's Guide
The Exterior of John G. Shedd Aquarium

The Explorer's Guide contains a treasure trove of aquatic science resources developed for use in K-12 classrooms. Back to Explorer's Guide.

Chambered Nautilus Scientific Name: Nautilus pompilius
Appearing to be a delicate creature, the nautilus is a brutal predator. Using 90 arms, the nautilus snatches up a shrimp or crab, passes its prey to its mouth, and crushes the crustacean’s shell with its beak. Nautilus will travel up to 1,500 feet each night to feed.

Region: Philippines

The chambered nautilus lives inside a shell that coils in circles. Just like sharks and many other fish, the nautilus camouflages itself with countershading. The top of the shell is dark and has a variety of stripes that breakup the outline of the animal. When viewed from above, the dark colors and stripes of the nautilus blend in with the dark ocean bottom. The bottom of the shell is white and blends in with the sunny waters above when viewed from below.

Sticking out from the shell is the nautiluses’ arms and a leathery hood that closes the animal into its shell for protection. Once closed, the hood is very hard for any animal to open.

This nautilus has more than 90 arms. The arms have folds and creases all over them, helping them to better grasp their prey. Within the center of all the tentacles lies the animal’s mouth where a beak, just like a bird, is located.

The chambered nautilus lives off steep slopes of coral reefs at depths of 1,200 to 1,500 feet (3,996 to 4,995 m). This is a safe place for them to live because they have few predators that live that deep. At night, the nautilus rises to the reef to catch its food.

The chambered nautilus is only found in the waters of the Pacific Ocean near Asia.

With a powerful beak like a bird, the nautilus cracks open the shells of crabs and shrimp and eats the animals hiding inside. After approaching a prey animal, the nautilus grasps the victim with its tentacles. Passing it to the center of the tentacles where the mouth is located, the nautilus uses its beak to crush the shell of the animal. Another feeding device, the tongue-like tooth radula, slices up the prey before the nautilus eats it.

The male nautilus has a modified arm which reaches out to deposit a packet of sperm on the female’s arms. The female stores the sperm and uses it when she produces eggs. Producing the eggs one at a time, she puts them into the sperm packet. Once all the eggs are inside, the female brings the fertilized eggs into warm, shallow waters, sticking them to rocks or corals. The young nautili feed off their eggs’ yolks until they are ready to hatch.

>A species or group of organisms that is in danger of extinction or disappearing from the face of the earth in the near future if its situation is not improved.

A species that can be found throughout its natural range but is declining in number and may become endangered in the absence of special protection efforts.

A species that is not declining in number but is of special concern because it is sensitive to pressure by particular human activities or natural events.

A species that is not declining in number and is not sensitive to pressures by human activities or natural events.

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Threats and Management
Unfortunately for the nautilus, people think their shell is very pretty. Each year thousands of these animals are killed so their shells can be sold. Only a small amount of those caught are taken for the pet trade. Animals in the pet trade are sold to pet stores, zoos, and aquariums.

Did You Know?
When threatened, the nautilus squirts ink, creating a smoky cloud in the water. Fogging the water, the nautilus can escape before the attacker can clearly see again.

The nautilus can not live in waters warmer than 77°F (25°C) for long periods. That’s one of the reasons they live in deep waters where it is cooler.

The nautilus is most closely related to the octopus, cuttlefish and squid. Of all the invertebrates or animals without backbones, this group has the most complex nervous system with a well developed brain.

The nautilus is the only member of its Class (Cephalopoda) that has a fully developed shell, which can be seen on the outside.

They are always in danger when coming to the reef to feed. Ferocious triggerfish will not stop trying until they break open the shell of the nautilus and eat the animal tucked inside.

This animal has been in the ocean for more than 400 million years ago. Back then, the nautilus was the most advanced and developed creature in the sea.

The shell of the nautilus is one of the most unique qualities of this animal. It makes its own shell. The mantle produces this shell, which is divided into chambers. A baby nautilus has about 4 chambers and an adult has about 30. Unlike a snail's shell, the nautilus' shell has many chambers that come after another, winding around in a spiral. The animal lives in the outermost chamber. A piece of the animal, which is a thin strand, runs through the walls of the chambers through a small hole. The hole made by this strand allows the chambers to be completely closed off. Through the small hole, the nautilus can fill the chambers it doesn’t occupy any more with gas or water. If the chambers are filled with gas, the animal will float. If the chambers are filled with water, the animal will sink. This system allows the animal to travel up from the depths of the ocean to feed at night.

A nautilus swims by using jet propulsion. By blowing water in and out of its mantle with a siphon or suction device that can be found under the tentacles, the nautilus can propel forward, backward or even sideways.

Web Sites:
NOTE: The following Web sites are not maintained by the John G. Shedd Aquarium and will open in a new browser window.

Waikiki Aquarium:

Print Publications:
Allen, G. R. & Stene, R. 1996. Indo-Pacific Coral Reef Field Guide. El Cajon, California: Odyssey Publishing Company. 378p. ISBN# 981-00-5687-7.

Allen, G. R. 1997. Tropical Marine Life. North Claredon, Vermont: Periplus Editions Ltd. 64p. ISBN# 962-593-157-0.

Banister, K. & Campbell, A. 1988. Encylopedia of Aquatic Life. New York, New York: Equinox (Oxford) Ltd. 349p. ISBN# 0-8160-1257-101-X.

Colin, P. L. & Arneson, C. 1995. Tropical Pacific Invertebrates. Beverly Hills, California: Coral Reef Press. 296p. ISBN# 0-9645625-0-2.

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Vocabulary Words

Countershading – A form of camouflage in which an animal has a dark-colored top and a light-colored bottom. When viewed from below, the animal blends in with the brightness of the sunny waters above. Viewed from above, the animal blends in with the dark ocean bottom. Countershading camouflages the animal, allowing it to sneak up on unsuspecting prey or hide from predators.

Extinction – An organism that has not been present on the face of the earth for over 50 years.

Hood – A leathery flap that can close a nautilus up into its shell for protection.

Invertebrate – An animal without a backbone.

Nautili – Plural for nautilus; more than one nautilus.

Organism – A living thing.

Pet trade – An industry or business in which animals are taken from the wild and sold to pet stores, zoos, and aquariums.

Radula – A structure that is like a combination of a tongue and teeth together that chews up food.

Species – A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.

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Chambered Nautilus
Chambered Nautilus

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