http://www.newsweek.com/chinese-scientists-are-using-sperm-whales-hide-secret-military-messages-1205120

Scientists in China have found a way to hide messages in the calls of sperm whales. The discovery could allow the military to use whales to send encoded messages hidden from any eavesdropping enemies.

Jiang Jiajia, from Tianjin University, and colleagues was leading research into how to camouflage underwater signals, making them harder to detect, the South China Morning Post reports. They were looking at sperm whales and their ability to use echolocation—using sound waves to locate and identify objects near them. Because these pulses are found throughout the world’s oceans, they are normally filtered out by reconnaissance systems looking for signals from submarines.