Water is an essential compound to most life onEarth. 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 lowerdensity than water enabling it to float on its surface. Another property is itssurface tension and the strong cohesive forces permitting organisms with ahigher density to travel across its upper most layer. Now, as you can tell thetwo of these properties are vital in sustaining aquatic life but, what if theseproperties were thrown away? Would the impact be catastrophic on marinespecies?Usually liquids compress when they are cooledand in return achieve a higher density.
However, water begins to contract until4oC where it reaches a maximum density. Beyond 4oC waterwill begin to expand as it freezes thus water molecules will be further apartin solid state, causing ice to have a lower density than water. The enlargementis due to the rapid formation of hydrogen bonds between negatively chargedoxygen atoms and positively charged hydrogen atoms in an unorderly fashion. So,when temperatures reach freezing there is little to no heat energy to break thebonds and each water molecule is held at a distance between neighboringmolecules equal to the length of hydrogen bonds.If ice was not less dense than water aquaticlife would probably end as it is known today. The preservation of marineanimals would practically be impossible since the ice would sink to the oceanfloor and begin to accumulate until it froze completely hence rendering almostall masses of water uninhabitable.
On the other hand, there are plans to begintowing multi-million-ton ice bergs to areas which are suffering from droughtsallowing the ice to melt and supply the region with sufficient water suppliesuntil the drought had passed. These plans would have collapsed if the densityof ice was higher than the density of water and leaving human society with noplausible safeguard against water shortages.H2O or water has a characteristicknown as surface tension. All liquids have a surface tension caused by cohesiveforces between the molecules of the liquid.
The molecules at the surface do nothave adjacent molecules in all directions therefore, they cohere significantlystronger to the molecules that directly conjoin with them being next to orbelow them. So, the molecules at the surface want to cling together throughcohesion which is the attraction between similar molecules.Water has the second highest known surfacetension second only to the element Mercury. This tension allows a multitude ofinsect species to walk across its surface and survive by feeding off the otherorganisms living at the top, or dead ones which floated to the surface.
Theseorganisms secrete surfactants or hydrophobic materials that allows them tosuspend themselves on water. Hydrophobic means that it is a liquid water wouldrather not bind to and would bind to other water molecules. If water binded toit the insect would penetrate the surface and sink, that would mean that theinsect is considered hydrophilic or water loving in simpler terms. The mayflyfor instance can float on water during a stage in their life cycle.
Once themayfly reaches the winged stage and becomes a subimago it sprouts hair on itsbody coated with a waxy hydrophobic layer which allows it to float on water.Other insects like the water strider have hydrophobic bodies with the exceptionof their claws so they can acquire a firm grip on the water and control thedirection of their movement.If water did not have high surfacetension many insects and birds would probably never come to be. As this aspectof waters physical properties is the key factor maintaining the group ofaquatic species inhabiting regions of low water quantity and high humidity,like swamps. So, if the surface tension was lower or non-existent multiplespecies of birds, insects, and other aquatic organisms would go extinct whichcould have severe negative impacts on the environments food chain causing rapiddecreases in the population of certain species.All in all, water has many uniqueproperties that defy common trends of other liquids like the expansion uponfreezing 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 isthe opposite. This peculiarity is the reason why the ocean is capable of beinga home for aquatic life and water the origin of all life since the oceans wouldfreeze completely if ice had a higher density than its liquid state. Itssurface tension also allows organisms with hydrophobic bodies orcharacteristics to thrive and balance the food chain maintaining the crucialyet basic circle of life.