Extreme cold seems to have contributed to the deaths of four thresher sharks that were recently found in Cape Cod Bay in Massachusetts—including a shark that was frozen completely solid. Even though this is not a common occurrence, it shows sharks are indeed affected by extreme cold temperatures.
Cold-stunning, which refers to the hypothermic reaction animals experience when exposed to extremely cold water, is typically associated with turtles. The symptoms of cold-stunning in air-breathing animals are initially decreased heart rate, decreased circulation and extreme tiredness, followed later by shock and pneumonia. If there is continued exposure to the cold water, cold-stunning can result in death.
Sea turtles are most commonly cold-stunned, especially when they fail to migrate to the warmer waters of the south when they should. Being cold-blooded, they rely on outside heat to warm their bodies, which is not possible in near-freezing water. National Aquarium Animal Rescue works to rehabilitate cold-stunned turtles and help them back into the ocean.
To learn more about cold-stunning, particularly with sea turtles, check out this video!