Question

Many fresh water animals cannot live for long in sea water mainly because of

• A. Change in the atmosphere
• B. Change in level of thermal tolerance
• C. Variation in light intensity
• D. Osmotic problems they would face
• E. Change in temperature and light

Answer 1

The correct option is D Osmotic problems they would face

Saline level of water ranges from less to moderate to high salt content. Therefore, there are different types of fishes living in different types of saline water. Some fish cannot live in areas where there is much salt and others need salt in the water to live. However, some fish can live in both salt water and freshwater. The fish however needs to keep its blood at a constant salinity and this, it does by the ability of 'asmoregulation'. They have different kidneys & gills in respect to the salinity level.

Many freshwater animals cannot live longer in sea water because freshwater animals have differently abled organs that allow osmoregulation that is different from the osmoregulation happening in sea water animals. Therefore the answer option D- "osmotic problems they would face".