why does aquatic life survive in arctic region when temeprature falls below 0 degree celcius?

Answer 1

There are a couple different reasons for this. First, remember they live in sea water, which does not freeze at 0c. Much arctic aquatic life also produce organic "anti-freeze" that lowers the temperature at which their fluids will freeze even further. Lastly, a large number of these creatures live at a depth where the water's pressure also retards freezing.

Answer 2

if the comprehensive earth flooded the salinity of the water could be decreased. There could be no clean water, so any aquatic existence that relies upon on clean water does not have the skill to stay to tell the story. The bigger volume of water might replace how and the place ocean currents lie, and the typical temperature of the water could be bigger than whilst there is land in the way, so the polar caps might soften inflicting the decrease in salinity. In result all aquatic existence could have been worn out. How did noah get 2 blue whales on the ark?

Answer 3

The animals have certain adaptations, like the antifreeze mentioned above. It's really quite amazing.
Another important characteristic about artic organisms is that their cell membranes are more fluid. That is, they have more unsaturated fatty acids in the lipid bilayer. Why unsaturated? That means that the fatty acid tails are spread further apart than saturated FAs, since they have kinks in the tails. This is important because is prevents freezing, crystallization and eventual fracture of the cell membranes.
High metabolism and lots of blubber also help keep them warm. They eat lots of fatty foods (seals, etc) in the months leading up to the cold season in order to store fat for energy and warmth.
Note that polar bears are included in this group!
There's a really cool fish (can't remember the name!) that goes into hibernation when the water above him freezes. He stops using aerobic metabolism. Result: his body is full of ethanol when he wakes up. The fish is producing alcohol, enough to get us drunk. Neat, eh?

Answer 4

also, remember the water freezes from the top down, so even if the surface is frozen there may well still be liquid water underneath.

Answer 5

Because SALT water is still liquid at that temperature.

Answer 6

anamolous expansion of water

Answer 7

They have antifreezing molecules in their structure.