Body Temperature Variability in the Australian Water Rat, Hydromys chrysogaster, in Air and Water

1980 ◽  
Vol 28 (2) ◽  
pp. 229 ◽  
Author(s):  
FD Fanning ◽  
TJ Dawson
Keyword(s):  
Heat Loss ◽  
Cold Water ◽  
Vascular System ◽  
Australian Water ◽  
The Poor ◽  
Air Temperatures ◽  
Level Of Activity ◽  
Eastern Australia ◽  
Stable Core ◽  
Hydromys Chrysogaster

Body and skin temperatures were recorded from water rats exposed to a range of air temperatures and also immersed in water at various temperatures. They were able to maintain stable core temperatures (mean 36.1�C, SD 0.65, n=61) at air temperatures up to 30�C. At 35�C they were unable to avoid hyperthermia despite their use of saliva spreading to enhance heat loss. Regional heterothermia was observed both in air and in water, but water rats were unable to maintain deep body temperatures at water temperatures lower than 25�C. Variations in the level of activity in cold water affected the rate of heat loss. Examination of the vascular system revealed the presence of various networks adapted for heat loss, but no major heat-conserving vascular retia. It is suggested that the poor thermoregulatory performance of water rats during aquatic excursions is largely due to the lack of heat-conserving retia, and to the poor insulative capacity of the fur when wet. The platypus, which possesses excellent fur insulation and a highly developed heat-conserving system, is a very competent homeotherm in cold water. The behavioural responses displayed by water rats which enable them to exploit the aquatic environment in south-eastern Australia are discussed.

Skinfolds and resting heat loss in cold air and water: temperature equivalence

1975 ◽  
Vol 39 (1) ◽  
pp. 93-102 ◽  
Author(s):  
R. M. Smith ◽  
J. M. Hanna
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Heat Loss ◽  
Air Temperature ◽  
Indirect Calorimetry ◽  
Cold Water ◽  
Heat Conductance ◽  
Air Temperatures ◽  
Body Core ◽  
Male Subjects

Fourteen male subjects with unweighted mean skinfolds (MSF) of 10.23 mm underwent several 3-h exposures to cold water and air of similar velocities in order to compare by indirect calorimetry the rate of heat loss in water and air. Measurements of heat loss (excluding the head) at each air temperature (Ta = 25, 20, 10 degrees C) and water temperature (Tw = 29–33 degrees C) were used in a linear approximation of overall heat transfer from body core (Tre) to air or water. We found the lower critical air and water temperatures to fall as a negative linear function of MSF. The slope of these lines was not significantly different in air and water with a mean of minus 0.237 degrees C/mm MSF. Overall heat conductance was 3.34 times greater in water. However, this value was not fixed but varied as an inverse curvilinear function of MSF. Thus, equivalent water-air temperatures also varied as a function of MSF. Between limits of 100–250% of resting heat loss the followingrelationships between MSF and equivalent water-air temperatures were found (see article).

Helminth Parasite Communities of the Water-rat, Hydromys chrysogaster, from Queensland

1997 ◽  
Vol 24 (4) ◽  
pp. 445 ◽  
Author(s):  
L. R. Smales ◽  
T. H. Cribb
Keyword(s):  
Bimodal Distribution ◽  
Helminth Fauna ◽  
Helminth Community ◽  
Parasite Communities ◽  
Far North ◽  
Core Species ◽  
Helminth Communities ◽  
Eastern Australia ◽  
Hydromys Chrysogaster ◽  
High Diversity

The helminth fauna from 124 water-rats, Hydromys chrysogaster, collected from 33 localities in Queensland was analysed. A total of 45 species of helminths was found, comprising 2 acanthocephalans, 2 cestodes, 13 nematodes and 28 trematodes. The helminth community of the water-rats in the region north of latitude 18˚ (far north) was different from that of water-rats south of 18˚ (central); Sorensen’s Index 45·8% similarity, whereas Holmes and Podesta’s Index gave 32·1% similarity. Comparisons with data from water-rats from southern and Tasmanian regions showed that they were different from each other and from both Queensland regions. The helminth communities were characterised by high diversity, dominated by trematodes in the central and Tasmanian regions, but with nematodes becoming more prominent in the far northern and southern regions. No core or secondary species were found in the Queensland helminth communities, the southern community was suggestive of a bimodal distribution and the Tasmanian had two core species. A checklist of helminth species occurring in water-rats from eastern Australia is provided.

The life-cycle of Echinoparyphium hydromyos sp.nov. (Digenea: Echinostomatidae) from the Australian water-rat

Parasitology ◽  
1967 ◽  
Vol 57 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. Madeline Angel
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Experimental Work ◽  
Field Work ◽  
Type Material ◽  
South Australian Museum ◽  
The South ◽  
Australian Water ◽  
Australian Museum ◽  
Hydromys Chrysogaster

Echinoparyphium hydromyos sp.nov. with forty-five collar spines is described from the Australian water rat, Hydromys chrysogaster Geoffr.The cercaria occurs naturally in Plananisus isingi (Cotton & Godfrey), and all stages in the life-history have been demonstrated experimentally.Encystation occurs in the kidneys of tadpoles.The adult is most closely related to Echinoparyphium recurvatum (Linstow). It differs from this in its greater number of eggs and in its life-history. E. recurvatum occurs predominantly in birds, and is rarely found naturally in mammals. E. hydromyos has been found only in a mammal.Cercaria echinoparyphii hydromyos is compared with C. clelandae Johnston and Angel; it differs from the latter in the ‘compound’ nature of the excretory granules. The adult of C. clelandae has not been demonstrated in spite of a number of experiments to determine it.Type material has been deposited in the South Australian Museum.I wish to acknowledge the help given by my colleague, Patricia M. Thomas, in field work and in other ways, and by Mr Ian Smith, of this department, in the experimental work on life-history studies.

Assessment of Convective Heat Loss From Humans in Cold Water

1978 ◽  
Vol 100 (1) ◽  
pp. 7-13 ◽  
Author(s):  
L. A. Kuehn
Keyword(s):  
Heat Loss ◽  
Convective Heat ◽  
Cold Water ◽  
Water Immersion ◽  
Physiological Data ◽  
Direct Calorimetry ◽  
Biophysical Models ◽  
Convective Heat Loss ◽  
Different Temperatures ◽  
Body Heat

Convective heat loss is a primary cause of hypothermia in humans undergoing water immersion, particularly for swimmers and divers at relatively shallow depths. Various biophysical models have been advanced to account for body heat loss in water of different temperatures and cold stress, most of which have made use of physiological data obtained with easily applied classical thermometry techniques. Explicit techniques for the determination of body heat loss must involve direct calorimetry or the use of heat flow transducers, techniques which are difficult to apply in realistic simulations of actual cold water exposure. This paper describes these latter two techniques in some detail, concentrating on the accuracy to be attained and the calibration necessitated with each method. Results obtained with each method specific to heat loss determination at surface and both dry and wet hyperbaric exposures are shown, illustrating the types of data that can be attained.

scholarly journals An Evaluation of Auditory Exostoses in 621 Prehistoric Human Skulls from Coastal Brazil

2007 ◽  
Vol 86 (8) ◽  
pp. 468-472 ◽  
Author(s):  
Maria Mercedes M. Okumura ◽  
Célia Helena C. Boyadjian ◽  
Sabine Eggers
Keyword(s):  
External Auditory Canal ◽  
Cold Water ◽  
Brazilian Coast ◽  
Multidisciplinary Research ◽  
Human Skull ◽  
Air Temperatures ◽  
Adult Humans ◽  
Human Skulls ◽  
Bone Anomalies ◽  
Water Sports

Auditory exostoses are bone anomalies located on the floor of the external auditory canal. They frequently develop in individuals who participate in water sports and other aquatic activities. Their etiology is probably multifactorial; development seems to be triggered by regular exposure to cold water, as well as to low air temperatures and/or cold winds. The presence of auditory exostoses has been recorded in human skull fossils that date back approximately 250,000 years. We conducted a study of auditory exostoses in 621 skulls of adult humans who had been part of a marine-dependent population that lived on the Brazilian coast between 5,400 and 800 years ago. The overall frequency of exostoses was 22%, but there was a great variance among different subgroups (0 to 56%). In this article, we propose some possible explanations for this variance. We also hope that our study will stimulate multidisciplinary research aimed at deciphering the intricate bony messages contained in cryptic archaeologic remains.

Energy exchanges of veal calves in relation to body weight, food intake and air temperature

1976 ◽  
Vol 23 (1) ◽  
pp. 35-42 ◽  
Author(s):  
A. J. F. Webster ◽  
J. G. Gordon ◽  
J. S. Smith
Keyword(s):  
Body Weight ◽  
Heat Loss ◽  
Heat Production ◽  
Live Weight ◽  
Milk Replacer ◽  
Total Heat Loss ◽  
Direct Calorimetry ◽  
Veal Calves ◽  
Air Temperatures ◽  
Energy Retention

SUMMARY1. Two series of energy balance trials were conducted with British Friesian veal calves. In the first, calves were given a milk replacer diet at three different planes of nutrition. In the second, calves were raised from about 80 to 180 kg at four air temperatures, 5°, 10°, 15° and 20°.2. The net efficiency of utilization of the milk replacer diet for growth was 0·72. The effect of body size on heat production in growing calves was best expressed by an exponent of body weight slightly but not significantly below W0·75.3. Measurements of heat production estimated from respiratory exchange and heat loss measured by direct calorimetry agreed exactly at all planes of nutrition. Heat production at zero energy retention was 675 kJ/kg W0·75 per 24 hr.4. Average daily live-weight gain and total heat loss were the same at all air temperatures. Changes during growth in the partition of heat loss into its sensible and evaporative components indicated that calves acclimated progressively to the air temperatures to which they were exposed.

Heat Production and Heat Loss in the Dog at 8–36°C Environmental Temperature

1958 ◽  
Vol 194 (1) ◽  
pp. 99-108 ◽  
Author(s):  
H. T. Hammel ◽  
C. H. Wyndham ◽  
J. D. Hardy
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Vascular System ◽  
Heat Content ◽  
Important Change ◽  
The Body ◽  
Critical Temperatures ◽  
Hot Environment ◽  
Environmental Temperatures ◽  
Made In

Metabolic and thermal responses of three dogs were made in a rapid responding calorimeter at temperatures ranging from 8°C to 36°C. These dogs were acclimatized to a kennel temperature of 27°C and had critical temperatures between 23°C and 25°C. The only physiological responses to low environmental temperatures were a moderate decrease in total heat content and an increase in heat production. The tissue conductance and the cooling constant of the fur did not effectively decrease below the levels obtaining throughout the neutral zone. In a hot environment heat loss from the respiratory tract was greatly increased. Although there was a great increase in the tissue conductance in the hot environment, conductance of heat through the tissue became decreasingly important as the air temperature approached body temperature so that panting became increasingly important for maintaining thermal balance. It is concluded that the vasomotor response of the peripheral vascular system is primarily a mechanism for dissipating excess heat produced during exercise; it is practically unimportant as a heat conserving mechanism. Effective changes in the total insulation of the fur can only be achieved by changing the surface area of the body, particularly those areas which are thinly furred, and not by any important change in the fur thickness through pilomotor activity.

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