BIOL1131 Lecture Notes - Lecture 6: Zebra Finch, Namib Desert, Ecophysiology
7 Jun 2018
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Locomotion
• All plants and animals have intracellular movement
o Using microfilaments or microtubules
o Essential for cell functioning
• Motile cells
o Able to move by amoeboid or ciliary movement, or move fluid
across their cell surface
• All animals (but only a few plants) are able to move parts of their body
• Amoeboid movement of cells
o A result of changes in the intracellular micro skeleton, and the
action of actin microfilaments or microtubules
• Ciliary movement
o Cilia are able to propel a cell or move fluid over a cell by rhythmic
beating movements – the POWER STROKE (moving back and
forth)
• Animal movement
o A consequence of muscle contraction, which exerts a force on the
external environment using an articulated skeleton as a rigid point
of attachment
• Animal locomotion
o Aquatic (buoyancy and swimming)
▪ Buoyancy force = the weight of the fluid the animal
displaces
▪ In air, buoyancy is negligible because the density of air is so
low
▪ Water is much denser, so the buoyancy force is often nearly
equal to the body weight
▪ Animals are usually a little more dense than water, and so
tend to sink
• To counteract this, many animals have a certain
volume of a low density material
• Some deep sea squid use ammonium chloride to fill
their body cavity, as it is less dense than sodium
chloride
• Some aquatic animals use a fat called squalene
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