The Surprising Breath-Holding Abilities of Hammerhead Sharks.
Researchers have discovered that scalloped hammerhead sharks hold their breath and seal their gills while diving more than half a mile below the ocean's surface to prevent heat from escaping through their gills at the deepest, coldest depths. This behavior, witnessed for the first time in fish, allows the sharks to maintain their body temperature at around 75 degrees Fahrenheit, even in water as cold as 39 degrees Fahrenheit. The discovery could help address potential vulnerabilities associated with changing ocean conditions or future human exploitation of these deep foraging habitats, as the scalloped hammerhead shark is a globally endangered species.