Meet the Thresher Shark

Chatterton smiled and allowed another diver to stay with Kohl for a while. He then moved to the back of the Seeker to help Yurga climb aboard. Still about two hundred feet from the stern of the boat, Yurga waved to Chatterton. Chatterton began to wave back, but his arm froze. Stalking Yurga from behind was an eighteen-foot monster. “Shark!” Chatter

In effect, that pioneering orca induced “tonic immobility” in its adversary—a temporary state of paralysis many species of sharks fall into when turned on their backs. The human discovery of tonic immobility in sharks is relatively recent, making the orca’s behavior all the more remarkable.