Respiratory metabolism of the desert millipede Orthoporus ornatus (Girard) (Diplopoda).

Abstract

Respiratory metabolism was measured each month for Orthoporus ornatus throughout a year. Respiratory rates were determined at a standard 20°C and at the mean ambient soil temperature at time of collection.No significant differences were noted between respiratory rates of reproductively mature males and females. A size relationship between live body weight and oxygen consumption per unit weight was found. The b values for 20°C and 25°C were-0.28 and-0.24, respectively. Premolt specimens had lower respiratory rates than postmolt individuals. There were significant differences between Q 10 values of animals exposed to temperatures above and below ambient field conditions.Seasonal changes in the use of metabolic reserves by O. ornatus were indicated by corresponding changes in RQ values.A "best estimate" of annual respiratory metabolism was 1332 cal g-1yr-1. Respiratory metabolism closely paralleled changes in ambient field temperature and was at its peak in July when animals were on the soil surface.