1. 1. Water loss and oxygen consumption were measured from three troglobitic (obligate cave dwellers) and one non-troglobitic cave species from the tropical but semi-arid Cape Range, Western Australia. The values are compared with those for epigean species of the same taxa sensu lato, measured both de novo and from the literature. 2. 2. The species include representatives of the Schizomida (Chelicerata), Araneae, Diplopoda and Isopoda. 3. 3. In ascending order the oxygen consumption (μlmg −1 hr −1) was: schizomids (0.24), cave millipedes (0.29), epigean millipedes (0.29), cave isopods (0.44) and epigean isopods (0.48). 4. 4. The cave millipedes have a high temperature coefficient for oxygen consumption: Q 10 22–30°C = 3.26. 5. 5. In ascending order the resistance (cm sec −1) to water loss was: cave isopods (22.4), epigean isopods (31.6), cave millipedes (40.9), schizomids (76.6), cave spiders (132.2) and epigean millipedes (878.1). 6. 6. The rate of oxygen consumption of the cave species is at the lower end of values taken from the literature for the relevant taxa but are not exceptionally low. 7. 7. The rates of water loss from cave species are high but comparative data are mostly lacking for comparison with epigean counterparts. Except for isopods the cave species have water loss rates around an order of magnitude greater than epigean species.
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