Nautilus pompilius

Geographic Range

Nautilus pompilius is found in the Indo-Pacific area. They primarily live near the bottom, in waters up to 500 meters deep, but rise closer to the surface throughout the night.

(Morton 1979)

Habitat

They live along the bottom of the shores and coral reefs of the South Pacific.

(Abbot 1935)

Physical Description

Nautilus pompilius can grow to a length of about 20 cm. The smooth thin shell spirals exogastrically, or above the animal, and has a pattern of brown and white. The animal creates chambers that increase in size as it moves to occupy the outermost chamber of its shell. An adult may have about 30 of these chambers. A tube called a siphuncle runs down the center of these chambers releasing a gas to maintain buoyancy and to keep N. Pompilius in an upright position. There is a tough hood where the anterior of its body connects to the shell. Below the hood protrudes about 90 small suckerless tentacles. Beneath, there is a funnel containing two separate lobes. The eyes contain no cornea or lens.

(Attenborough 1979, Morton 1979, Brusca and Brusca 1990)

Reproduction

This species reproduces sexually through internal fertilization and reaches sexual maturity at age 15 to 20 years. Four of the tentacles on the male form the spandix, which transfers sperm by means of a spermatophore. A spermatophore contains an elongated sperm mass that adheres to the female's mantle wall. The protective coating disintegrates, releasing the sperm. They then lay oblong eggs that are around 1.5 inches in length. The newly hatched chambered nautilus has a small shell that is about one inch in diameter.

(Brusca and Brusca 1990, Dybas 1994)

Behavior

The muscles of the funnel contract to cause N. pompilius to swim. They steer mostly by sensing obstacles with their tentacles or lightly bumping into them before changing course. When not swimming, it uses tentacles to pull itself along rocks. This species is nocturnal.

(Borradaile and Potts 1961, Morton 1979)

Food Habits

Due to its primitive eyes and sensitivity to light, N. pompilius relies on its sense of smell to detect the fishes and crabs that it feeds on. They also feed on carrion.

(Attenborough 1979, Morton 1979)

Economic Importance for Humans: Positive

Researchers study N. pompilius for many reasons. First, there is a process called biominetrics that strives to synthetically produce such organic materials as nacre, or the mother of pearl that lines the inside of N. pompilius' shell. This thin coating is incredibly strong, and this synthesized material would be used in small machines. Researchers are mainly interested in understanding how these materials are made naturally. In addition, N. pompilius has the most highly developed pinhole eyes, making them the subject of much research. This relatively uncommon eye type lacks lenses.

(Clery 1992, Nilsson 1989)

Other Comments

These chamber-shelled cephalopods first appeared around 550 million years ago. The peak of its ancestors' dominance was during the early Paleozoic era where some had shells with a length of twenty or thirty feet if uncoiled. Despite this rich fossil record, only six closely related species of this genus are known to still exist. They are now referred to as living fossils because of their evolutionary history.

(Attenborough 1979, Abbot 1935, Dybas 1994)

Contributors

Beth Goetz (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

References

Abbot, C. 1935. Geological History. New York: Smithsonial Institution Series, Inc..

Attenborough, D. 1979. Life on Earth. Boston: Little, Brown and Company.

Borradaile, L., F. Potts. 1961. The Invertebrata. London: Cambridge University Press.

Brusca, .., .. Brusca. 1990. Invertebrates. Massachusetts: Sunaver Associates.

Clery, D. March 28, 1992. The Mother of All Pearls. New Scientist: 25.

Dybas, C. October, 1994. Crossing a Squid and a Seashell. Sea Frontiers: 22-23, 54.

Morton, .. 1979. Molluscs. London: Hutchinson & Co..

Nilsson, D. May, 1998. Vision Optics and Evolution. BioScience: 298-307.