Reexamining echidna physiology: The big picture for Tachyglossus aculeatus acanthion
MetadataShow full item record
The early divergence of monotremes and therian mammals has resulted in considerable interest in the comparative physiology of the short-beaked echidna (Tachyglossus aculeatus), the most common and widespread living monotreme. However, there are many and varied interpretations of its physiology, reflecting the many and varied studies, limitations and uncertainties of aspects of some previous studies, and potential differences between the various subspecies. Consequently, we thoroughly examine here the standardized physiology of the most widely distributed subspecies of short-beaked echidna (T. aculeatus acanthion) over a wide range of ambient temperatures to definitively assess its physiology in a comparative context. We conclude that the low and variable body temperature of the short-beaked echidna is physiologically “primitive,” but it also reflects adaptation to its myrmecophagous niche. Other aspects of its physiology are more typically mammalian. A low metabolic rate reflects its low body temperature, and ventilatory variables are matched to accommodate a modest gas exchange requirement. Thermal conductance is typical for a mammal of equivalent mass. In contrast to previous studies, we demonstrate that short-beaked echidnas can enhance evaporative water loss above thermoneutrality, like other mammals, with a similar capacity for evaporative heat loss. Cooling of their nasal blood sinus with nasalmucousmay contribute to this enhanced evaporative cooling. Their capacity to evaporatively cool explains how their distribution can include habitats where ambient temperature, even in shelters, exceeds their supposed critical thermal limit.
© 2016 by The University of Chicago.
Showing items related by title, author, creator and subject.
Barker, Justine Megan (2016)The short-beaked echidna has a combination of ancestral and derived physiological traits. Its physiology is less primitive than previously thought, with many aspects being typically mammalian, including a previously ...
The private life of echidnas: Using accelerometry and GPS to examine field biomechanics and assess the ecological impact of a widespread, semi-fossorial monotremeClemente, C.; Cooper, Christine; Withers, Philip; Freakley, C.; Singh, S.; Terrill, P. (2016)The short-beaked echidna (Tachyglossus aculeatus) is a monotreme and therefore provides a unique combination of phylogenetic history, morphological differentiation and ecological specialisation for a mammal. The echidna ...
Atypical residency of short-beaked common dolphins (Delphinus delphis) to a shallow, urbanised embayment in south-eastern AustraliaMason, S.; Salgado Kent, Chandra; Donnelly, D.; Weir, J.; Bilgmann, K. (2016)Short-beaked common dolphins (Delphinus delphis) are typically considered highly mobile, offshore delphinids. This study assessed the residency of a small community of short-beaked common dolphins in the shallow, urbanized ...