Graphics Reference
In-Depth Information
FIG 4.35
Cat pounce sequence.
Hauling Loads
Animals carrying loads suffer a general increase in energy cost of locomotion.
Although there may be some noticeable differences in gait, such as a head
held lower than in a normal walk, the upright stance is maintained. However,
when an animal is hauling a load, the change in stance may be more
noticeable. Horses that pull carts may maintain a very similar posture to a
normal walk, particularly once the inertia of the load is overcome and forward
momentum of the load achieved. The differences are more noticeable with
heavier loads or when the animal is pulling against pressure that is constant,
such as in plowing. In this instance a horse can be seen to be holding its head
less upright; it is generally extended either forward or downward. The forward
reach of the horse's legs may be shortened slightly while the backward thrust
is extended. This gives the appearance of the body being angled forward, an
effect enhanced by the hips being held lower than in an ordinary walk. This
stance enables the horse to deliver more power to the hind legs, which are
providing the main source of thrust for forward locomotion.
Group Action
Many animals gather together in herds, flocks, shoals, or crowds. Such group
actions have benefits in protection from predators, as is the case with the
flocking of starlings as they go to roost or the bait-balling behavior of sardines
in the presence of predators such as dolphins, seals, or larger fish. Animal
groupings obviously offer benefits to those animals; group bonding is one
such benefit. Some animals choose to live in extended family groups or larger
troupes of various sizes throughout their lives; others come together more
