title: Gas exchange characteristics, metabolic rate and water loss of the Heelwalker, Karoophasma biedouwensis (Mantophasmatodea: Austrophasmatidae).
abstract: This study presents the first physiological information for a member of the wingless Mantophasmatodea, or Heelwalkers. This species shows cyclic gas exchange with no evidence of a Flutter period (more typical of discontinuous gas exchange in insects) and no indication that the spiracles are fully occluded during quiescent metabolism. Standard metabolic rate at 20 degrees C was 21.32+/-2.73 microl CO(2)h(-1) (mean+/-S.E.), with a Q(10) (10-25 degrees C) of 1.7. Increases in V()CO(2) associated with variation in mass and with trial temperature were modulated by an increase in burst period volume and a decline in cycle frequency. Total water loss rate, determined by infrared gas analysis, was 0.876+/-0.08 mg H(2)Oh(-1) (range 0.602-1.577, n=11) whilst cuticular water loss rate, estimated by linear regression of total water loss rate and metabolic rate, was 0.618+/-0.09 mg H(2)Oh(-1) (range 0.341-1.363, n=11). Respiratory water loss rate was therefore no more than 29% of the total rate of water loss. Both total water loss rate and estimated cuticular water loss rate were significantly repeatable, with intraclass correlation coefficients of 0.745 and 0.553, respectively.
authors.affiliation: DST-NRF Centre for Invasion Biology, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa. slchown@sun.ac.za
authors.forename: S L
authors.initials: SL
authors.lastname: Chown
authors.forename: E
authors.initials: E
authors.lastname: Marais
authors.forename: M D
authors.initials: MD
authors.lastname: Picker
authors.forename: J S
authors.initials: JS
authors.lastname: Terblanche
mesh_terms: D000818:Animals; D001481:Basal Metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D005260:Female; D007313:Insecta / Q000378:metabolism*; D008297:Male; D014867:Water / Q000378:metabolism*; D014870:Water Loss, Insensible
chemical_list: D014867:Water; D002245:Carbon Dioxide