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The discontinuous gas exchange cycle of the pseudoscorpion Garypus californicus, mean mass 5.9 …


Biology Articles » Anatomy & Physiology » Physiology, Animal » Discontinuous gas exchange in a tracheate arthropod, the pseudoscorpion Garypus californicus: Occurrence, characteristics and temperature dependence

Abstract
- Discontinuous gas exchange in a tracheate arthropod, the pseudoscorpion Garypus californicus: Occurrence, characteristics and temperature dependence

Discontinuous gas exchange in a tracheate arthropod, the pseudoscorpion Garypus californicus: Occurrence, characteristics and temperature dependence

John R.B. Lighton, Barbara Joos

Department of Biological Sciences, University of Nevada at Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4004.
Jrlighton@aol.com

Abbreviations
C phase closed spiracle
DGC discontinuous gas exchange cycle
O phase open spiracle
VCO2 rate of CO2 emission

The discontinuous gas exchange cycle of the pseudoscorpion Garypus californicus, mean mass 5.9 mg, is rudimentary and is characterized by bursts of CO2 at frequencies ranging from 3.6 mHz at 15 °C to 13.3 mHz at 35 °C. The mean volume of CO2 emitted per burst is 3.6 µl g-1 at 25 °C, about a tenth of the amount emitted by tracheate arthropods with a well developed discontinuous gas exchange cycle. Interburst CO2 emission is high and increases with temperature, reaching near 45% of total CO2 production rate at 35 °C. No fluttering spiracle phase is evident. The metabolic rate of G. californicus at 25 °C (8.4 µW) is typical of other arthropods. We infer from the high rate of interburst CO2 emission in G. californicus that trans-spiracular O2 partial pressure gradients are small and that spiracular conductance is correspondingly high, which may lead to high rates of respiratory water loss relative to arthropods with more stringent spiracular control and higher CO2 buffering capacity. The typical moist, hypogeal environments and small body sizes of pseudoscorpions correlate well with their respiratory physiology.

Journal of Insect Science, 2:23. Open Access Article.


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