Take a big inhale and a deep dive. Imagine staying underwater as long as possible. Now imagine a shark approaching, with gleaming teeth, and swimming away as fast as you can. Imagine trying to do both at the same time.
You are not alone if you find this confusing. Freeze and flight responses are often mutually exclusive. If you try to do both at once, your brain and muscles will run out of oxygen. However, a recent study found this paradoxical behavior in narwhals when they respond to novel threats.
The research was conducted by scientists from UC Santa Cruz and the Greenland Institute of Natural Resources. With the help of hunters in East Greenland, the scientific team used suction cups to attach satellite tags on narwhals, before releasing them back into the wild. Scientists were able to track nine narwhals, as well as monitor their depth, acceleration, and heart rates. Researches studied the physiological response of the narwhals during escape dives, in which the narwhals try to escape from net entanglement. The team found that narwhal heart rates reached incredibly low rates of 3 to 4 beats per min, indicating an innate freeze mode to conserve oxygen. During this escape period the narwhals also made faster strokes and used more oxygen than during normal dives, somewhat paradoxical behavior.
Whether such complex escape response leads to disorientation or death in marine mammals remains to be determined. However, physiological studies like this one can help researchers better regulate expanding activities in the Arctic environment. After all, we need to understand the impact our behavior has on marine mammals.
Original Research Article:
Narwhals Wearing Heart Monitors Reveal Danger of Human Encounters – National Geographic