Abstract
Excavation of burrows is an extremely physically demanding activity producing a large amount of metabolic heat. Dissipation of its surplus is crucial to avoid the risk of overheating, but in subterranean mammals it is complicated due to the absence of notable body extremities and high humidity in their burrows. IR-thermography in a previous study on two species of African mole-rats revealed that body heat was dissipated mainly through the ventral body part, which is notably less furred. Here, we analyzed the dorsal and ventral skin morphology, to test if dermal characteristics could contribute to higher heat dissipation through the ventral body part. The thickness of the epidermis and dermis and the presence, extent and connectivity of fat tissue in the dermis were examined using routine histological methods, while vascular density was evaluated using fluorescent dye and confocal microscopy in the giant mole-rat Fukomys mechowii. As in other hitherto studied subterranean mammals, no subcutaneous adipose tissue was found. All examined skin characteristics were very similar for both dorsal and ventral regions: relative content of adipose tissue in the dermis (14.4 ± 3.7% dorsally and 11.0 ± 4.0% ventrally), connectivity of dermal fat (98.5 ± 2.8% and 95.5 ± 6.8%), vascular density (26.5 ± 3.3% and 22.7 ± 2.3%). Absence of large differences in measured characteristics between particular body regions indicates that the thermal windows are determined mainly by the pelage characteristics.
Highlights
IntroductionMammals are able to maintain a stable and relatively high body temperature in a wide range of ambient temperatures, which is achieved by heat production and heat loss regulation (McNab, 2002; Withers et al, 2016)
In the proximal region of the wing of the Brazilian free-tailed bat Tadarida brasiliensis, a network of arteries and veins positioned perpendicular to the body has been found, which is unique among bats and which is considered to be a thermal window allowing effective thermoregulation during migration (Reichard et al, 2010)
We focus on skin characteristics of the social F. mechowii, a species in which the role of ventral body size in heat dissipation has been suggested on the grounds of its higher surface temperatures and lower pelage insulation (Šumbera et al, 2007; Okrouhlík et al, 2015)
Summary
Mammals are able to maintain a stable and relatively high body temperature in a wide range of ambient temperatures, which is achieved by heat production and heat loss regulation (McNab, 2002; Withers et al, 2016). Heat dissipation in mammals can be enhanced in body areas known as thermal windows (Feldhamer et al, 2015; Withers et al, 2016). These areas are usually sparsely haired and situated at body appendages as pinnae in elephants or rabbits (Mohler & Heath, 1988; Weissenböck et al, 2010), tail in coypus and beavers (Krattenmacher & Rübsamen, 1987; Steen & Steen, 1965), or feet in foxes or otters (Klir & Heath, 1994; Kuhn & Meyer, 2009). There are, for example, two main blood vessel plexuses beneath the dark patches of giraffe skin considered as thermal windows, which facilitate heat exchange with the environment (Ackerman, 1976; Mitchell & Skinner, 2004). In the proximal region of the wing of the Brazilian free-tailed bat Tadarida brasiliensis, a network of arteries and veins positioned perpendicular to the body has been found, which is unique among bats and which is considered to be a thermal window allowing effective thermoregulation during migration (Reichard et al, 2010)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
