. The Australian zoologist. Zoology; Zoology; Zoology. MONOTREMES AND HOMEOTHERMY histological examination of adipose tissues. The low level of NST is further indi- cated by the low level of oxygen consumption of inactive monotremes. Dawson (this volume) has shown very low levels in the New Guinea long-beaked echidna Zaglossus. Oxygen consumption is at its lowest in inactive Tachyglossus at about Ta 25°C. Under these conditions oxygen is consumed at about ml/gm body weight/hour. This is about one third the level predicted for eutherians of equal weight based on the factor W"025
. The Australian zoologist. Zoology; Zoology; Zoology. MONOTREMES AND HOMEOTHERMY histological examination of adipose tissues. The low level of NST is further indi- cated by the low level of oxygen consumption of inactive monotremes. Dawson (this volume) has shown very low levels in the New Guinea long-beaked echidna Zaglossus. Oxygen consumption is at its lowest in inactive Tachyglossus at about Ta 25°C. Under these conditions oxygen is consumed at about ml/gm body weight/hour. This is about one third the level predicted for eutherians of equal weight based on the factor W"025 (Augee 1976). This value does not allow for differences in Tb between echidnas and eutherians. A few metabolic measure- ments obtained under experimental conditions on echidnas with Tb near 38°C do give higher values which are approximately 70% that predicted for eutherians (Augee 1976). MONOTREMES ARE NOT HIBERNATORS As long as echidnas are supplied with sufficient food they resist torpor regard- less of Ta (Augee et al, 1970). In all instances of reported torpor in echidnas there is evidence that, generally due to an inappropriate diet, the animals were in a condition of weight loss. The prime evidence cited as support for monotreme hibernation is a paper by Wardlaw (1915). However, he states that his animals were "rather emaciated", and most appear to have weighed less than 2 kg on capture. Wardlaw (1915) did observe periods of torpor lasting from one to seven days. However, of his seven animals, three did not recover from their first torpor and died without rewarming. Three others became active after one bout of torpor, became torpid a second time and then died without rewarming. The last animal survived, but it is unclear if it ever became torpid. Hibernation is generally TUBULE DIAMETFH. Sm\. ' FEB.' MAR. ' APR ' MAY ' JUNE ' JULY ' AUG. ' SEPT ' OCT ' NOV ' DEC FIG. 5.—Season reproductive changes in male echidnas. Figure from Wendy Baldwin. 115. Please note
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1914
