Torpor in the Echidna, Tachyglossus aculeatus

Augee, M. L.; Ealey, E. H. M.

doi:10.2307/1378202

Cited by 42 publications

(25 citation statements)

References 7 publications

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“…Secondly, even inactive animals may be under stress in artificial surroundings and this stress may contribute to an increased body temperature again though increased metabolic heat production. Augee and Ealey (1968) monitored the heart rates of echidnas using probes inserted via hollow spines, which seemed not to induce as much struggling.…”

Section: Discussionmentioning

confidence: 99%

Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field

Brice

Grigg

Beard

et al. 2002

Journal of Thermal Biology

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Abstract(1) Echidnas occur throughout the hot arid zone of Australia yet laboratory studies have concluded that they are ill equipped physiologically to manage T a higher than 35°C. (2) Consequently, it is generally assumed that echidnas must rely on behavioural thermoregulation, being nocturnal in hot weather and seeking less extreme microclimates during the day.(3) By monitoring T b of echidnas in the field and relating these to T a within their day time shelters in Western Queensland during summer, this study showed that echidnas are able to tolerate T a of 35-40°C in hollow logs for up to 10 h. (4) Further, as T b remains < T a in these situations, echidnas may have physiological mechanisms for dealing with the heat after all.

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Section: Discussionmentioning

confidence: 99%

Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field

Brice

Grigg

Beard

et al. 2002

Journal of Thermal Biology

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“…The field data show that peak rewarming rates of echidnas (7.2 ± 0.8°C h − 1 , Table 1) are much greater than the rate measured by Augee and Ealey (1968) of 2.2°C h − 1 , which was used in the analysis of Geiser and Baudinette (1990). However, this rate came from a study where torpor was induced by starvation, which would have depleted energy reserves, whereas natural hibernation in echidnas occurs after they have laid down significant fat stores (Falkenstein et al, 2001).…”

Section: Rewarming From Deep Torpormentioning

confidence: 83%

Rewarming rates and thermogenesis in hibernating echidnas

Nicol

Andersen

2008

Comparative Biochemistry and Physiology Part A: Molecular &

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We measured body temperatures (T b ) in 14 free-ranging echidnas (Tachyglossus aculeatus) using implanted data-loggers. An average of 1020 ± 744 days of T b data was recorded from each animal. The average maximum T b was 35.3 ± 0.7°C (n = 14), and the lowest T b was 4.7°C. Detailed analysis of rewarming events from four echidnas showed rewarming time to be dependent on initial T b (rewarming time in hours = 15.6 − 0.41T initial , n = 31) with an average rewarming rate of 1.9 ± 0.4°C h − 1 . Based on an hourly sampling rate, the peak rewarming rate was found to be 7.2 ± 0.8°C h − 1 (n = 12), which was measured at a mean T b of 26.2 ± 2.4°C. This rate of heating was calculated to be equivalent to a peak oxygen consumption rate of 1.4 ± 0.2 ml O 2 g h − 1 , approximately 9 times the basal metabolic rate. We found that a plot of rate of change of T b against T b for the entire data set from an individual echidna provided a useful summary and analytical tool.

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“…Body temperatures of adrenalectomized echidnas were measured with thermocouple probes inserted through the base of a spine on the dorsal body surface in the pectoral region. The positioning of the probes and intraperitoneal trans¬ mitters, and comparison of temperatures obtained in this way with those obtained by mercury thermometers inserted into the rectum, have been reported previously (Augee & Ealey, 1968 Heart rate was measured with a standard clinical electrocardiograph. The leads were attached to hypodermic needles inserted through the base of a spine.…”

Section: Methodsmentioning

confidence: 99%

“…If exposure to cold is continued for more than 1 day the body temperature begins to fluctuate, but the mean temperature is maintained indefinitely at about 28°C provided the animal is able to maintain an adequate food intake (Augee & Ealey, 1968). If food is withheld, normal echidnas in ambient temperatures of 0-10°C eventually become torpid with body temperatures falling to the ambient temperature.…”

mentioning

confidence: 99%

Role of the Adrenal Cortex in the Adaptation of the Monotreme Tachyglossus Aculeatus to Low Environmental Temperature

Augee¹,

McDonald²

1973

Journal of Endocrinology

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When exposed to a low ambient temperature of 5 \ s=deg\ C, adrenalectomized echidnas were able to increase their metabolic rate and to maintain their body temperature within the normal range for no more than 48 h \ p=m-\ less than 12 h in five out of six animals. Thereafter, activity, metabolic rate, cardiac rate and body temperature declined and the animals became torpid.When maintained with daily i.m. injections of 1\p=n-\2mg cortisol acetate/kg, adrenalectomized echidnas maintained activity and normal body temperature in the cold environment indefinitely. When cortisol injections were withheld and exposure to cold continued, normal body temperature was maintained for a further 10 days, after which it declined rapidly.The onset of torpor was always preceded by a marked fall in plasma glucose concentration, as occurred in normal, but fasted, echidnas after prolonged exposure to cold. Both cortisol and corticosterone have glucocorticoid activity in echidnas, and torpor was prevented in adrenalectomized echidnas by preventing the fall in plasma glucose with either intermittent injections or constant rate infusions of glucose solutions.The adrenal glands of normal echidnas exposed repeatedly to low environmental temperatures showed marked hypertrophy and increase in lipid content.It is concluded that adrenocortical secretions are necessary for the metabolic response to cold stress in these prototherian mammals, and a major role of the corticosteroids is in maintenance of normal blood glucose concentrations, presumably by enhancing hepatic gluconeogenesis.

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Torpor in the Echidna, Tachyglossus aculeatus

Cited by 42 publications

References 7 publications

Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field

Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field

Rewarming rates and thermogenesis in hibernating echidnas

Role of the Adrenal Cortex in the Adaptation of the Monotreme Tachyglossus Aculeatus to Low Environmental Temperature

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