Marine mammals, such as whales and dolphins, can dive to great depths without experiencing decompression sickness, also known as the bends. This is because they have evolved physiological adaptations that allow them to withstand the high pressure changes that occur during diving. However, there is still much that is not understood about how marine mammals avoid the bends.

A new study published in the journal "Frontiers in Physiology" offers a new hypothesis that may help to explain how marine mammals are able to avoid the bends. The study, conducted by researchers from the University of California, San Diego, suggests that marine mammals may use a process called "denitrogenation" to reduce the amount of nitrogen in their tissues before diving. This process involves exhaling carbon dioxide, which in turn causes the body to release nitrogen.

When a marine mammal dives, the pressure of the water increases, which causes the nitrogen in the body's tissues to dissolve into the bloodstream. This can lead to decompression sickness if the marine mammal ascends too quickly, as the nitrogen bubbles can form in the body and cause tissue damage. By reducing the amount of nitrogen in the body before diving, marine mammals may be able to reduce the risk of decompression sickness.

The study also highlights the potential role that sonar plays in marine mammal strandings. Sonar is a technology that uses sound waves to detect objects underwater. When sonar is used at high frequencies, it can produce loud noises that can cause marine mammals to panic and ascend too quickly, which can lead to decompression sickness.

The researchers suggest that further research is needed to better understand how marine mammals avoid the bends and the potential role that sonar plays in marine mammal strandings. This information could help to develop strategies to reduce the risk of decompression sickness in marine mammals and to mitigate the impacts of sonar on marine mammal populations.