For most sharks, the front end is the dangerous bit. Thresher sharks are the exception. They’re deadly at both ends, because they’ve managed to weaponise their tails.

The top halves of their scythe-like tail fins are so huge that they can be as long as the rest of the shark. For around a century, people have been saying that the threshers lash out at their prey with these distended fins—hence the name. But no one had ever seen them do so in the wild.

In 2010, one team showed that they can lash out at tethered bait under controlled conditions. But Simon Oliver has done better. His team spent the summer of 2010 in the Philippines, watching and filming wild pelagic