http://waquarium.otted.hawaii.edu/research/cephalopod_biology.html
Biology and embryology of the
chambered nautilus (Nautilus belauensis)
The Waikiki Aquarium collaborated with Dr. John Arnold, formerly from the University of Hawaii, Dr. Bruce Saunders of Bryn Mawr College, Dr. Peter Ward of the University of Washington, Dr. Neil Landman of the American Museum of Natural History, and others, to unlock the secrets of this "living fossil".
In 1984, we used sonic transmitters to track living Nautilus belauensis in Palau, Micronesia, in order to learn more about its daily movements. We discovered that Nautilus moves as deep as 467 meters (1541 ft.) during the day, and at dusk ascends to depths as shallow as 85 meters (280 ft.). Temperatures at these depths ranged from 8º C to 24º C (46º to 75º F).
Using the results from our field research, we constructed aquariums that allowed temperatures to vary from 14º C to 22º C (57º to 72º F). The aquariums were not pressurized. Adult nautilus in these aquariums laid eggs continuously over several years. The eggs were maintained in separate incubator tanks at a constant temperature of 22º C (72º F), corresponding to the water temperature in the shallower depths visited by the adult nautilus at night. This "guess" at the correct incubator temperature resulted in the discovery of the first nautilus embryos known to science in 1985. A preliminary description of the nautilus embryo was published in Science in 1986. We predicted that the embryo would take up to a year to hatch -- a prediction that was confirmed in December 1988, when our colleagues in Japan hatched the first nautilus. On October 27, 1990, we hatched our first Nautilus belauensis. Of the ten hatchlings produced at the Waikiki Aquarium, two survived to over one year of age, providing the first growth data on young nautilus.
http://www.dal.ca/~ceph/TCP/Npompil.html
Nautilus pompilius
Nautilus and Allonautilus are the last living genera of externally shelled cephalopods (Ward 1983 and 1987, CephBase 2002). These slow moving Cephalopods sre considered primitive when compared to their faster moving relatives. In addition to having an external shell, these cephalopods do not have lenses in their eyes.
As far back as the ancient Greeks, the shell of the chambered nautilus has been a symbol of perfection. There is a mathematical proportion that the Ancient Greeks called The Golden Ratio that describes the growth of nautilus shell. This proportion is consistent through out the shell and is 1:1.618 Click here for more information on The Nautilus Shell Spiral.
Nautiloids and ammonoids were once one of the dominant groups, both in terms of number of species and biomass, found in the ocean's of the world (See the Fossil Cephalopods FAQ). Nautiluses are living fossils and have been around for 500 million years. The remaining seve species of Nautilus and Allonautilus are living fossils. Nautiluses have been on the planet for 500 million years!
The external shell of these animals provides both protection and rigid open spaces that can be filled with gas for buoyancy. Carlson et al (1984) reports that tagged Nautilus belauensis descend to a depth of 476 meters and move approximately 0.45 - 0.8 km in an average day.
Unfortunately for Nautiluses, their are shells attractive to humans and many are killed each year. Indonesia had banned the collection and export since 1987 but many other countries still collect and kill them. A small percentage are also taken for the aquarium trade. Dr. Peter Ward reports hearing that the situation New Caledonia is a catastrophe. Over a period of two years or less, 10,000 live Nautilus were captured and killed for their shells.
One reason that nautiluses are not protected by CITIES is that we don't have much scientific information on them. We do know that they have extremely slow reproductive rates, especially when compared to other cephalopods. Nautilus take perhaps 5 to 10 years to reach maturity and only lay a dozen or so eggs in a year. Once mature, Nautilus produce eggs over many years. This means that if their population is severely depressed it will take a long time for them to recover. In contrast, most cephalopods only live a year and produce many smaller offspring. Many cephalopods only reproduce once and die.
At Dalhousie I've worked with nautiluses while investigating their activity patterns with Dr. Webber and Dr. O'Dor. I have to say, Nautilus are not much like squid, octopuses and cuttlefish. They are interesting for scientific reasons but they don't rapidly change color, are not as active and do not seem to be anywhere near as intelligent and responsive as the other cephalopods. They are basically swimming snails. These major differences are not suprisingly as they diverged from modern cephalopods before there were bony fish in the ocean.
In aquaria they may live for a long time but they have buoyancy problems (they tend to float at the top) and problems producing new shell (the new shell is discolored and black). There are no known solutions to these problems. Only two places have ever been able to get them to successfully reproduce in captivity; Waikiki Aquarium and an aquarium in Japan. Their eggs have never been found in the wild. As far as I know, no one has ever raised a hatchling to maturity in captivity. For these reasons they are not, in my opinion, a good pet choice for home aquarists and I therefore have not written a popular article on their care in captivity.
References and Credits
Credits
Photograph by James B. Wood Photography.
References
