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In-Depth Information
of huge amounts of energy in a very short period of time for scurrying to take
place. The level of energy required for scurrying would therefore demand
much larger muscles, which in turn would increase the weight of the leg and
as a consequence the demand for more power. Likewise, when very large legs
are in motion, they gain a great deal of momentum, which becomes difficult
to shed very quickly in order to come to rest. Legs the size of an elephant's
could not do this at a speed quick enough to constitute a scurrying motion;
the strain on the skeletal structure would be too great. Small dinosaurs may
have been able to turn their heads with the speed of a bird, but this would
have been impossible for the larger dinosaurs such as the brontosaurus or the
tyrannosaurus. Obviously, the study of these now extinct animals is limited
to the study of their fossilized remains, so there is a degree of conjecture and
not a little controversy among paleontologists regarding the details of these
creatures. However, it is possible to make reasonable assumptions about their
movements based on their skeletal structures, their size, and the comparative
study of animals that exist today; they are, after all, subject to the same
natural laws as those extinct creatures.
Flying as a mode of locomotion also has its limitations. Birds are limited in
their size due to the power-to-size ratio. Muscles needed to provide the
power for flight have an upper limit on their effectiveness. Size may also limit
the type of movement possible. Because of the manner in which they fly the
hummingbird has natural limits to the size it is able to achieve: about the size
of a blackbird. Any larger than that and a hummingbird will not be capable of
flapping its wings sufficiently quickly to create the necessary lift. Nature really
is the supreme designer.
The Principles of Locomotion
The methods of locomotion that various creatures use to get around vary
greatly from species to species, but despite these differences there are some
common features of locomotion, such as maneuverability, that they all share.
All creatures also have to deal with and operate within the same laws of physics.
What is interesting is the way that different types of animals approach the
problem of getting around in very similar environments. For example, it's not
only fish that swim. Some birds, mammals, insects, spiders, and reptiles have
taken to the water too. Likewise, there are fish that quite regularly take to the
air. All these animals have one other thing in common: They have all evolved
modes of movement through need.
Speed
The importance of speed to an animal is not simply a choice of movement
based on a whim; it may be a matter of life or death. It has become necessary
for some animals to be able to move at high speeds to catch their food, and
conversely it has become important for other animals to be able to achieve
