Hammerhead sharks 'hold their breath' in deeper, colder waters, research shows
Sharks are ectotherms and their internal body temperatures usually reflect the waters they swim in. Holding their breath helps them function in the frigid deep.
Sharks are among the best swimmers on the planet, but new research suggests that even they sometimes "hold their breath" while diving deep underwater.
The reason is that sharks are ectothermic, or cold-blooded, and their body temperature essentially matches the waters they swim in. To do deep dives, they must conserve body heat, and the best way to do that is to tightly close
