the trachea of goat, pig, and striped dolphin were compressed
between two plates. We, therefore, assumed that PD,S in a diving
marine mammal was similar to that of a terrestrial mammal. As
Cozzi et al. (2005) did not measure the relationship between pressure
and volume during their compression tests, we modelled the
dead space as a compressible tube using data for terrestrial animals
and an equation adapted from Aljuri et al. (1999):