Environmental Engineering Reference
In-Depth Information
4.5 (a) Energy cost of surface and submerged swimming
(based on T. M. Williams 1999). (b) Cross-sections of fish
bodies showing two distinct placements of aerobic muscles: in
most fish species they run laterally just under the skin, but in
tuna and lamnid sharks they are deep inside the body (based
on Shadwick 2005).
red (aerobic) muscles deep within their bodies, where
other fish have only white anaerobic fibers, but also by
their regional endothermy; those internal muscles can be
10
C-20
C warmer than the surrounding water (fig.
4.5) (Shadwick 2005). The aerobic red muscles are kept
warm by constant contractions; if the fish stopped swim-
ming, the muscles would stop working and might never
bounce back (Bernal et al. 2005).
Flying animals can be found in each of the five classes
of vertebrates. But it is the flight of birds, swift and ma-
neuverable, that has been so envied by humans and that
has led to millennia of unfulfilled dreams and failed emu-
lations (Hart 1985). Humans simply lack the radical
avian adaptations: lengthening of forelimbs to produce
wings delivering sufficient lift and thrust, muscles strong
enough to sustain the flapping, a respiratory system supe-
rior to mammals' in its extraction of atmospheric oxygen.
The minimum energy costs of flying can be estimated
from the loss of potential energy in gliding. Birds and
bats losing 1-2.5 m/s reduce their potential energy
