seaquake strands 150 melon-headed whales in Japan
April 10, 2015 : Extreme changes in diving pressure generated during a seaquake caused barotrauma in the cranial air sinuses of a pod of melon-headed dolphins on 22 March (see below). Because they use the air in their sinuses and air sacs serve as acoustic mirrors bouncing, focusing, and channeling returning echo location and navigation clicks in a fashion to make their biosonar work, a pressure-related tear in the membranes of these air spaces knocks out their navigation. They swim blindly downstream in the path of least drag arriving at a 6-mile stretch of Hokota Beach about 60 miles northeast of Tokyo Japan on Friday morning. Words of an AFP journalist at the scene revealed that the pod has no sense of direction. He wrote that despite efforts to push the dolphins to deep water, they were being washed back onto the beach by the incoming surface current ( link ). That they could not swim to freedom against the incoming flow indicates that they have no acoustic sense of direction...