| dc.description.abstract | The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL,
456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric
methods. These data increase fivefold the range of body masses for which bat lung data are available, and
allow more representative allometric equations to be formulated for bats.
2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung
parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94 0 in PP to 89 0
in PH. Of the components of the parenchyma, the alveoli composed 89 0 and the blood capillaries about
500.
3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the
capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary
endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 ptm)
and PP had the thickest (0.3033 ptm).
4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the
surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total
morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of
the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher
unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange
performance of its lungs.
5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot
always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these
pulmonary structural disparities in different species of bats must await additional physiological and flight
biomechanical studies.
6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data
(b = 0.82) exceeds the value for flight V02 (b = 0.70), those for the surface area of the blood-gas (tissue)
barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung
diffusing capacity for oxygen (b = 0.69) all correspond closely to the Vo2 value. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying
mammals reveal that superiority of the bat lung over that of the non-flying mammal. However, the bat
parameters relative to those of non-flying mammals deteriorate towards the higher body size range,
because of the generally steeper slopes of the equations for non-flying mammals. Allometric comparisons
also reveal that small-size bats have, in general, better adapted lungs than birds of equivalent size but at
the higher body mass scale, bats are generally inferior to birds. | en |
