Nautilus macromphalus

Nautilus species are sometimes referred to as ‘living fossils’ due to being the sole survivors of a once extremely specious subclass.

Identification

N. macromphalus has an open umbilcus in which the inner coils of the shell are visible. This opening may be up to 15% of the total shell diameter. No callus is present in this species.

Habitat

Nautilus macromphalus inhabits continental shelf and slope waters associated with coral reefs, from the surface to a depth of about 500m.

Distribution

Southwestern Pacific Ocean, off north-eastern Australia, New Caledonia and Loyalty Islands.

Feeding and diet

Nautiluses have very poor eyesight and use scent and touch to recognise and find food. They are mainly scavengers and N. macromphalus may rise to water <20m deep to feed during the night. Movement vertically through the water column is achieved by adjusting gases held in their chambered body to alter buoyancy.

Life history cycle

Nautilus species have a life span of up to 20 years.

Economic impacts

N. macromphalus supports a substantial shell trade, mostly from beach drift specimens, subsistence and artisanal fisheries. The outer layers of the shell are sometimes removed to reveal a silvery mother-of-pearl outer surface. The meat for human consumption is limited to local markets mainly in New Caledonia.

References

• Japanese Expert Consultation on Living Nautilus (JECOLN). (1980). Nautilus macromphalus in captivity, Tokai University Press, Tokyo.
• Jereb, P., & Roper, C.F.E (eds). (2005). Cephalopods of the World: Chambered Nautiluses and Sepioids, Food & Agriculture Organization of the United Nations, Rome.
• Norman, M. (2000). Cephalopods - A World Guide, ConchBooks, Germany.
• Norman, M., & Reid, A. (2000). A Guide to Squid, Cuttlefish and Octopuses of Australasia, CSIRO Publishing, Victoria.