How do aquatic mammals maintain homeostasis while under water for so long?

Answer 1

There are many ways in which aquatic mammals maintain homeostasis underwater.

One way is using a countercurrent exchange system for heat. Blood is warmest at the center of the animal's body, and coolest around the body's extremities, which are in contact with the cold ocean water.

In a countercurrent heat exchange system, blood that has reached the extremities and has cooled down returns to the heart in veins. As this happens, hot blood from the heart travels in arteries towards the extremities. In this opposing system, the arteries carrying warm blood from the center of the body transfer heat to the cooled blood in the veins. This allows an animal to retain body heat in a cold aquatic environment. A good example of this is with whales.

Another way is through the usage of insulation. Many animals, such as seals, have a layer of blubber (fat), which insulates them from the cold.

Some other methods of regulating homeostasis underwater include osmoregulation for maintaining solute concentrations, diving to different water depths to adjust temperature, and keeping large internal oxygen stores.