The hammerhead shark lives in the shallow, warm, waters of the tropics — but it hunts in the dark and chilly waters far below.
How does it cope with the transition from tropical temperatures to near-Arctic? The answer, according to new research, is it holds its breath.
For most of the day, hammerheads swim in waters of around 25C. Their prey lives in a very different environment. More than half a kilometre down, the sharks feed on slow moving fish, squid and crustaceans. To reach them, they have to dive for many minutes and endure a temperature drop of 20C.
Until now, how they did this physiologically has been something of a mystery. Maintaining a warm body temperature should be crucial for the cold-blooded sharks,
