Temperature Regulation in the Platypus, Ornithorhynchus anatinus: Production and Loss of Metabolic Heat in Air and Water

Grant, Tom; Dawson, Terence J.

doi:10.1086/physzool.51.4.30160956

Cited by 68 publications

(40 citation statements)

References 31 publications

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“…Grant & Dawson (1978b) found that the temperature inside an arti¢cially constructed platypus burrow remained between 14 and 18 8C while the outside air temperature in their study area went from 75.5 to 33.5 8C during the same period. Although the cooling capacity of water means that high thermal stress does not generally occur while individuals are foraging in water, the loss of metabolic heat produced during exercise in water at temperatures higher than the normal body temperature of the species means that animals cannot tolerate such water temperatures (Grant & Dawson 1978a,b).…”

Section: Temperature Regulation and Hibernationmentioning

confidence: 87%

“…Studies of captive platypuses (Grant & Dawson 1978a,b), and radio-telemetric work on free-ranging animals (Grant 1983b;Grigg et al 1992), have shown the erroneous nature of these earlier conclusions, as platypuses were found to maintain homeothermy while foraging for hours in water below 5 8C. A constant body temperature is maintained in actively foraging animals by an increase in their metabolic activity, the excellent fur and tissue insulation and the possession of a vascular counter-current heat exchange system at the base of the hind legs and tail (Grant & Dawson 1978b). Bennett (1835Bennett ( , 1860 indicated that platypuses could be seen in Australian rivers at all seasons of the year, but because of his observations that the species was more abundant in summer than in winter, he speculated on the possibility that individuals may`not in some degree hybernate'.…”

Section: Temperature Regulation and Hibernationmentioning

confidence: 99%

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Field biology of the platypus (Ornithorhynchus anatinus): historical and current perspectives

Grant

Temple-Smith

1998

Phil. Trans. R. Soc. Lond. B

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The ¢eld biology of the platypus, Ornithorhynchus anatinus, was ¢rst studied by a number of expatriate biologists who visited the Australian colonies to collect specimens in the 1800s. Their work was followed in the early to mid-1900s by a group of resident natural historians and later by an increasing number of academic biologists. All of these workers contributed signi¢cantly to the current understanding of the ¢eld biology of this unique Australian species. The platypus occupies much the same general distribution as it did prior to European occupation of Australia, except for its loss from the state of South Australia. However, local changes and fragmentation of distribution due to human modi¢cation of its habitat are documented. The species currently inhabits eastern Australia from around Cooktown in the north to Tasmania in the south. Although not found in the west-£owing rivers of northern Queensland, it inhabits the upper reaches of rivers £owing to the west and north of the dividing ranges in the south of the state and in New South Wales and Victoria. Its current and historical abundance, however, is less well known and it has probably declined in numbers, although still being considered as common over most of its current range. The species was extensively hunted for its fur until around this turn of this century. The platypus is mostly nocturnal in its foraging activities, being predominantly an opportunistic carnivore of benthic invertebrates. The species is homeothermic, maintaining its low body temperature (32 8C), even while foraging for hours in water below 5 8C. Its major habitat requirements include both riverine and riparian features which maintain a supply of benthic prey species and consolidated banks into which resting and nesting burrows can be excavated. The species exhibits a single breeding season, with mating occurring in late winter or spring and young ¢rst emerging into the water after 3^4 months of nurture by the lactating females in the nesting burrows. Natural history observations, mark and recapture studies and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a polygynous mating system. Recent ¢eld studies have largely con¢rmed and extended the work of the early biologists and natural historians.

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Section: Temperature Regulation and Hibernationmentioning

confidence: 87%

Section: Temperature Regulation and Hibernationmentioning

confidence: 99%

Field biology of the platypus (Ornithorhynchus anatinus): historical and current perspectives

Grant

Temple-Smith

1998

Phil. Trans. R. Soc. Lond. B

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“…Fur seals, muskrats, mink, otters, beavers, and the platypus maintain a pelage air layer for thermal insulation underwater, whereas most other aquatic mammals become wet to the skin (Johansen 1962;Grant and Dawson 1978;Costa and Kooyman 1982;Williams 1986;Riedman 1990). Seals and sea lions exhale before submergence and rely for metabolism mainly on oxygen stored in their large volume of blood (Kanwisher 1 986), whereas inshore species such as otters,and muskrats probably carry larger volumes of respiratory air during dives (e.g., sea otters, Kooyman 1989, p. 40).…”

Section: Introductionmentioning

confidence: 99%

Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.)

Lovvorn¹,

Jones²

1991

Can. J. Zool.

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LOVVORN, J. R., and JONES, D. R. 1991. Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.). Can. J. Zool. 69: 2879-2887. Recent studies of diving ducks (Aythya spp.) have shown that buoyancy is far more important to locomotor costs of shallow diving than is hydrodynamic drag. Working with Canvasbacks (A. valisineria), Redheads (A. americana), and Lesser Scaup (A. aflnis), we investi ated factors affecting buoyancy in models of locomotor energetics. Body volume can be accurately estimated from body mass ( rf = 0.82-0.95), but equations sometimes differ among species, and body volume relative to mass is higher in winter than in summer. Wing molt does not influence body volume or buoyancy. In scaup, an increase in body lipid from 35 to 190 g (from 5.4 to 22.3% of body mass) increases the energy costs of descent more through the inertial effects of higher mass and added mass of entrained water (82.8% of change) than through greater work against drag (12.0%) or buoyancy (5.2%). Costs of foraging at the bottom are 20% lower in the fatter birds because increased inertial resistance to the buoyant force is greater than the increase in buoyancy. Maximal changes in body lipid and associated hypertrophied muscle raise overall costs of diving to a depth of 2 m by only 2%. Such effects can be offset by altering respiratory and plumage air volumes (+I5 mL for a 155-g lipid increase) or the relative amount of time spent at the bottom. Hence, diving energetics contrast with the energetics of flight, which are strongly affected by body mass changes. Reduced buoyancy from compression of air spaces with depth lowers costs of bottom foraging in scaup by 24% at 1.2 m and 36% at 2 m. Mass-specific plumage air volume decreases with increasing body mass (slope = 0.12)' and body tissues are incompressible relative to air. Thus, buoyancy decreases faster with increasing pressure in smaller birds and they become negatively buoyant at shallower depths (about 43 m for Oldsquaws, Clangula hyemalis). Ducks such as eiders (Somateria spp.) weighing over 1200 g and diving to less than 60 m probably never become negatively buoyant. LOVVORN, J. R., et JONES, D. R. 1991. Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.). Can. J. Zool. 69 : 2879-2887. Des etudes rkcentes sur les canards plongeurs (Aythya spp.) ont dkmontrk que la flottabilitk contribue beaucoup plus que la trainke hydrodynamique au coQt de la locomotion au cours de la plongke. Nous avons tent6 de dkteminer les facteurs qui affectent la flottabilitk en ktudiant des Morillons h dos blanc (A. valisineria), des Morillons h tCte rouge (A. americana) et des Petits Morillons (A. aflnis) et en intCgrant nos rksultats h des mod&les d'knergie locomotrice. Le volume du corps peut Ctre estimk justement d9apr&s la masse corporelle (2 = 0,82-0,97), mais les equations different parfois selon l'esp&ce et les rapportsvolume/masse sont plus ClevCs en hiver qu'en k...

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“…For example, the sea otter (Enhydra lutris), coypus (Myocastor coypus) and platypus (Ornithorhynchus anatinus) all exhibit BMRs that are substantially greater than those of other closely related members of their respective lineages [7,9,12]. Like C. cristata with which it shares a largely sympatric range and semi-aquatic habits, the northern water shrew this T a was close to the upper limit of thermoneutrality.…”

Section: Discussionmentioning

confidence: 95%

“…Considering their large surface area-to-volume ratio and the exceptional thermal conductivity of water compared to air, it is not surprising that most small-bodied, semi-aquatic mammals are unable to maintain core T b while immersed, and tend to cool rapidly in the aquatic medium [18], but see [12,36] for exceptions. Cold acclimation in shrews is accompanied by an elevation of BMR and maximal heat-producing capabilities [8].…”

Section: Discussionmentioning

confidence: 99%

Fasting metabolism and thermoregulatory competence of the star-nosed mole, Condylura cristata (Talpidae: Condylurinae)

Campbell

McIntyre

MacArthur

1999

Comparative Biochemistry and Physiology Part A: Molecular &

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Metabolic and body temperature (T b ) responses of star-nosed moles (Condylura cristata) exposed to air temperatures ranging from 0 to 33°C were investigated. The thermoneutral zone of this semi-aquatic mole extended from 24.5 to 33°C, over which its basal rate of metabolism averaged 2.25 ml O 2 g − 1 h − 1 (45.16 J g − 1 h − 1 ). This rate of metabolism is higher than predicted for terrestrial forms, and substantially higher than for other moles examined to date. Minimum thermal conductance was nearly identical to that predicted for similar-sized eutherians and may represent a compromise between the need to dissipate heat while digging and foraging in subterranean burrows, and the need to conserve heat and avoid hypothermia during exposure to cold. C. cristata precisely regulated T b (mean 9SE =37.790.05°C) over the entire range of test temperatures. Over three separate 24-h periods, T b of a radio-implanted mole varied from 36.6 to 38.8°C, and generally tracked level of activity. No obvious circadian variation in T b and activity was apparent, although cyclic 2 -4 h intervals of activity punctuated by periods of inactivity lasting 3-5 h were routinely observed. We suggest that the elevated basal metabolic rate and relatively high T b of star-nosed moles may reflect the semi-aquatic habits of this unique talpid.

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Temperature Regulation in the Platypus, Ornithorhynchus anatinus: Production and Loss of Metabolic Heat in Air and Water

Cited by 68 publications

References 31 publications

Field biology of the platypus (Ornithorhynchus anatinus): historical and current perspectives

Field biology of the platypus (Ornithorhynchus anatinus): historical and current perspectives

Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.)

Fasting metabolism and thermoregulatory competence of the star-nosed mole, Condylura cristata (Talpidae: Condylurinae)

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