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Septum morphology and bathymetry in cephalopods

Published online by Cambridge University Press:  08 February 2016

Gerd E. G. Westermann  and
Peter Ward
Gerd E. G. Westermann
Affiliation:
Department of Geology, McMaster University, Hamilton, Ontario L8S 4M1
Peter Ward
Affiliation:
Geology Department, University of California, Davis, California 95616
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Abstract

Nautilus pompilius at Fiji lives abundantly to about 600 m depth while the shell implodes between 730–900 m when sunk in a cage. From this, and the average parameters of the septum, its tensile strength is calculated to 110–140 MPa. This is markedly higher than the latest value from direct tensile tests (78 MPa). In recent pressure tests by Saunders and Wehman with dry shells from the Philippines, implosion occurred at pressure equivalents to 310–680 m depth, without significant correlation with septal thickness. We attribute this excessive range and non-correlation to structural damage by postnecrotic processes. The recalculated tensile strength from their original data is 56–137 MPa; the higher values are compatible with our values for septal nacre of Nautilus and Spirula (c. 155 MPa). Septal curvature and thickness in orthocones thus remain useful guides to bathymetry.

Type
Articles
Information
Paleobiology , Volume 6 , Issue 1 , Winter 1980 , pp. 48 - 50
Copyright
Copyright © The Paleontological Society 

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References

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