REASONS WHY FISH SURVIVE IN COLD ICE OCEAN

THE REASONS WHY FISH SURVIVE IN COLD ICE OCEAN ARE:

In icy cold winters months, lakes and rivers freeze over forming ice, the fish and other aquatic animals manage to survive. Animals like seals, penguins, walruses and a wide variety of sea birds are all fish eaters, they live in the arctic and Antarctic circle, amidst the ice caps. The land is completely frozen. Yet these animals manage to live in this region. How do they do it?

The icy waters of the arctic and Antarctic oceans support a great amount of marine life for millions of years, life has remained undamaged making it possible for these animals to adapt themselves to these partial of excretions.  

But they do get some help from nature. All liquid have a boiling point and a freezing point. When water boils at a certain temperature it turns into steam. When it cools to a certain temperature it freezes and become ice. Water boils at 100 degree Celsius (100⁰c) and freezes at 0⁰c. When the outsides temperature falls below the freezing point of waters, lakes and rivers yet frozen.

However only the top layer of lakes or river freeze. Underneath the frozen upper layer, the water remains in its liquid form and does not freeze. Also, oxygen is trapped beneath the layer of ice. As a result, fish and other aquatic animals find it possible to live comfortably in the frozen lakes and ponds.

But why doesn’t the entire body if water freeze, like a giant, lake – sized ice cubes? Generally, all liquids expand on heating, but water is an exception to this rule. If water is heated, its volume continues till the temperature rises to 4⁰c. At temperatures over 4⁰c water starts expanding. It then keeps expanding with the further rise in temperature, till finally at 100⁰c it turns into steam.

In other words, at 4⁰c, water has the least volume (occupies the least amount if space) and maximum density (is at its heaviest) this irregular expansion if water called anomalous expansion. This anomalous expansion plays an important role by only freezing the upper layer in lakes and rivers.

During winter months in colder countries the outside or atmosphere temperature is very low it drops to below freezing and the upper layers of waters in the lakes and ponds start cooling. When the temperature of the surface layers fall to 4⁰c the waters body acquires maximum density and sinks down. The water that sinks down displaces water below, and the lower layers of water simultaneously rise up. This also gets cooled to 4⁰c and again sinks down.

When the temperature of the water body finally goes down below 4⁰c the density or heaviness of water decreases and as a result water does not sink down. The surface water finally freezes at 0⁰c while the lower part still remains at 4⁰c. the light frozen layer of ice floats on top.

Ice does not allow heat to pass through it easily, so the freezing of the waters below is a very slow process. At depth below 30 meters, temperatures are cold and stables, but food is source. As a result animals have adapted to this situation by growing more slowly.

There are other dangers that fish face in freezing waters like deaths. The body fluid of an ordinary fish can solidify if the temperature of the surrounding water drops below 5⁰c, so Arctic and Antarctic fish have adjusted to their surrounding in an interesting manner.

Certain species of cod, polar fish have a reduced metabolic rate and produce anti freeze molecules called glycoprotein to reduce the freezing point of their body fluids. One could look at it as the fishy version of bears hibernating, a survival tactic that has seen theses friends outlive many other creature on earth.