[M.sub.b] = body mass, [VO.sub.2] = oxygen consumption at 20[degrees]C, BLV = book lung volume, [D.sub.t][O.sub.2] = oxygen diffusion capacity, [DtO2.sup.m] = mass-specific oxygen diffusion capacity, and [DELTA][PO.sub.2] = required gradient of partial oxygen pressures between air and hemolymph to support these [VO.sub.2] values.
In this study we hypothesized that Grammostola rosea Walckenaer 1837, an active predator of large size that depends on its two paired book lungs for respiration, would have a refined low energy strategy based on its thin air-hemolymph barrier.