Nautilus
(Nautilus sp.)
Facts
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IUCN NOT EVALUATED (NE)
Facts about this animal
The Nautilus is an archaic member of cephalopods still possessing a chambered, coiled shell of 16 to 26.8 cm in diameter. Only the last of the up to 36 chambers is inhabited whereas the others, filled with gas and fluid, are used to regulate buoyancy. Gas pressure is hold constant at 0.91 atm and the body is moved in and out to change water displacement in order to sink or rise. The shell is patterned with brown stripes above and is white below, both serving as camouflage. Arranged in two circles the foot possesses about 82 to 90 retractable tentacles which have no suckers. A dorsal hood can close the shell to protect the soft parts. The animal moves slowly by ejecting breathing water from the ventral mantle cavity, which contains four gills, through the siphon. The olfactory sense is thought to be the primary one but a pair of quite large, open pinhole eyes is also present. These probably just serve to recognize the diurnal fluctuation of light.
Nautiluses make vertical migrations from 300 to 450 m depth where they hide by day to 90 m depth by night where they forage of shrimps, other crustaceans, carrion and small fishes. The only known natural enemy is the Octopus which can crack the shell.
The large eggs are laid individually in leathery capsules and adhered to rocks or corals near the surface. The hatchlings will emerge after 12 months. They yet have a four-chambered shell. Life may last up to 20 years.
Did you know?
that only 5-6 extant species exist of this 500 million year old group of cephalopods having their greatest radiation in the Ordovician about 450 million years ago? that the shell of a Nautilus contains gas-filled chambers and therefore will implode at a depth greater than 800 m? that the Nautilus has no ink to protect itself like other cephalopods because it can hide in its shell?
| Factsheet | |
|---|---|
| Class | CEPHALOPODA |
| Order | NAUTILIDA |
| Suborder | NAUTILINA |
| Family | NAUTILIDAE |
| Name (Scientific) | Nautilus sp. |
| Name (English) | Nautilus |
| Name (French) | Nautile |
| Name (German) | Perlboot, Nautilus |
| Name (Spanish) | Nautilus |
| CITES Status | Not listed |
| CMS Status | Not listed |
Photo Copyright by
Lee R. Berger
Distribution
| Distribution | |
|---|---|
| Range | Indo-Pacific ocean from the Andaman Islands to Fiji. |
| Habitat | At the slopes of tropical reefs at a depth of 90 to 450 m in open water or above the reef. Rocks or corals near the surface seem to be necessary for the deposition of eggs and their development. |
| Wild population | The species are living in marine ecosystems in 90-450 m depth where appropriate counting is not possible. Fishermen, however, report to catch up to 20 specimens per net draw. |
| Zoo population | 28 reported to ISIS (2008) |
In the Zoo
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Why do zoos keep this animal
Much in the life cycle of the Nautilus is unknown because of its hardly accessible habitat. Therefore, some aquariums try to breed them in captivity which failed until recently.
Adults are shown for educational reasons to illustrate shelled cephalopods which had a great radiation in former epochs.
How this animal should be kept
It is rather easy to keep. Use 400 l glass tanks with the background formed with concrete and fiber glass and a biological filter submerged in the gravelly bottom. Nautilus shall be kept at the rather cool conditions of their natural habitat (13 °C) because warm water may induce reproduction. Eggs and adults shall be kept in different tanks because of different temperature preferences. Animals can be fed with shrimps (also small crustaceans and fishes). Although buoyancy is regulated Nautilus may hang around being attached with some tentacles to the walls of the tank during much of the time with only short periods of activity in between.