Water is an essential compound to most life on
Earth. It has many properties that aid in the survival of living organisms.
Which include the expansion of water upon freezing allowing ice to have a lower
density than water enabling it to float on its surface. Another property is its
surface tension and the strong cohesive forces permitting organisms with a
higher density to travel across its upper most layer. Now, as you can tell the
two of these properties are vital in sustaining aquatic life but, what if these
properties were thrown away? Would the impact be catastrophic on marine
Usually liquids compress when they are cooled
and in return achieve a higher density. However, water begins to contract until
4oC where it reaches a maximum density. Beyond 4oC water
will begin to expand as it freezes thus water molecules will be further apart
in solid state, causing ice to have a lower density than water. The enlargement
is due to the rapid formation of hydrogen bonds between negatively charged
oxygen atoms and positively charged hydrogen atoms in an unorderly fashion. So,
when temperatures reach freezing there is little to no heat energy to break the
bonds and each water molecule is held at a distance between neighboring
molecules equal to the length of hydrogen bonds.
If ice was not less dense than water aquatic
life would probably end as it is known today. The preservation of marine
animals would practically be impossible since the ice would sink to the ocean
floor and begin to accumulate until it froze completely hence rendering almost
all masses of water uninhabitable. On the other hand, there are plans to begin
towing multi-million-ton ice bergs to areas which are suffering from droughts
allowing the ice to melt and supply the region with sufficient water supplies
until the drought had passed. These plans would have collapsed if the density
of ice was higher than the density of water and leaving human society with no
plausible safeguard against water shortages.
H2O or water has a characteristic
known as surface tension. All liquids have a surface tension caused by cohesive
forces between the molecules of the liquid. The molecules at the surface do not
have adjacent molecules in all directions therefore, they cohere significantly
stronger to the molecules that directly conjoin with them being next to or
below them. So, the molecules at the surface want to cling together through
cohesion which is the attraction between similar molecules.
Water has the second highest known surface
tension second only to the element Mercury. This tension allows a multitude of
insect species to walk across its surface and survive by feeding off the other
organisms living at the top, or dead ones which floated to the surface. These
organisms secrete surfactants or hydrophobic materials that allows them to
suspend themselves on water. Hydrophobic means that it is a liquid water would
rather not bind to and would bind to other water molecules. If water binded to
it the insect would penetrate the surface and sink, that would mean that the
insect is considered hydrophilic or water loving in simpler terms. The mayfly
for instance can float on water during a stage in their life cycle. Once the
mayfly reaches the winged stage and becomes a subimago it sprouts hair on its
body coated with a waxy hydrophobic layer which allows it to float on water.
Other insects like the water strider have hydrophobic bodies with the exception
of their claws so they can acquire a firm grip on the water and control the
direction of their movement.
If water did not have high surface
tension many insects and birds would probably never come to be. As this aspect
of waters physical properties is the key factor maintaining the group of
aquatic species inhabiting regions of low water quantity and high humidity,
like swamps. So, if the surface tension was lower or non-existent multiple
species of birds, insects, and other aquatic organisms would go extinct which
could have severe negative impacts on the environments food chain causing rapid
decreases in the population of certain species.
All in all, water has many unique
properties that defy common trends of other liquids like the expansion upon
freezing causing it to have a lower density and its high surface tension.
Liquids tend to contract when cooled and achieve a higher density but, water is
the opposite. This peculiarity is the reason why the ocean is capable of being
a home for aquatic life and water the origin of all life since the oceans would
freeze completely if ice had a higher density than its liquid state. Its
surface tension also allows organisms with hydrophobic bodies or
characteristics to thrive and balance the food chain maintaining the crucial
yet basic circle of life.