Thermal dependence of locomotory energetics and aerobic capacity of the Gila monster (Heloderma suspectum)

Henry B. John-Alder, Charles H. Lowe, Albert F. Bennett

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The thermal dependencies of sustainable locomotion and aerobic energetics were determined in the Gila monster, a lizard of relatively low thermal preference. Maximal aerobic speed (MAS) is 0.70 km/h at 25°C and 1.03 km/h at 35°C (Q10=1.5). Endurance declines as speed is increased above MAS, and Gila monsters are unusual in being unable to engage in brief periods of high-speed burst locomotion. The rate of O2 consumption ( {Mathematical expression}) during locomotion has the same thermal dependence as that of MAS. Maximal {Mathematical expression}'s are 0.594 ml O2/(g·h) at 25°C and 0.896 ml O2/(g·h) at 35°C (Q10=1.5). The masscorrected {Mathematical expression} max of the Gila monsters is highest among lizards at 25°C and is relatively high, consistent with other platynotans, among lizards at 35°C. Net cost of locomotion is temperature independent and is relatively low among lizards. Low net cost of locomotion together with high {Mathematical expression} max's lead to Gila monsters having high MAS's at both 25°C and 35°C. Gila monsters thus appear to be well adapted for aerobic, sustainable activity. The total cost of locomotion shows a positive thermal dependence. However, the minimum cost of transport, attained at the highest sustainable speed, is temperature independent. Locomotion at MAS becomes faster with increasing body temperature with no obligatory increase in total cost of locomotion.

Original languageEnglish (US)
Pages (from-to)119-126
Number of pages8
JournalJournal of Comparative Physiology ■ B
Issue number2
StatePublished - Jun 1983
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology


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