Why do whales beach themselves?
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When whales or other aquatic mammals wash onto the shore, they are usually unable to return to the sea without help. What exactly causes a whale to beach, and how can scientists prevent it? Tune in and learn more in this episode.
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Diving pods of offshore toothed whales and dolphins (odontoceti) feed on squid above mid-oceanic ridges where they are often exposed to oscillations in ambient water pressure when shallow-focused earthquakes suddenly erupt in the seafloor below them. On rare occasion these changes in pressure are too excessive and/or too rapid to be counterbalanced by the whales' pressure regulating anatomy resulting in barotrauma in the sinuses and air sacs of each animal's head. Since echo-navigation and echo-location are not possible without intact and functional sinuses and air sacs, a pressure related injury in this system renders the victims unable to use their acoustic navigation system to determine their position and find food. Nor are they able to dive without suffering intense pain. The injured pod huddles together for protection against sharks and swims slowly away from the epicenter, but not in a random direction. Rather, increased resistance (drag) to swimming against or perpendicular to the surface flow will turn the whales headfirst and point them in the path of the least drag, which is always downstream with the flow of the surface currents.
Many barotraumatized pods recover after an unknown period of rest on the surface. Those that do not recover are eventually: (a) guided to a stranding beach by the surface current, (b) harvested by sharks and killer whales, or (c) die and sink to the bottom. Decomposing gases will form in the carcasses that sink in water less than 100 meters deep. The gases formed after about a week underwater will re-float these carcasses and they will then be carried by the surface currents to a beach.
Non-navigating whales, carcasses, and flotsam are deposited on beaches because the current that carried each grain of sand to build the beach in the first place, is the same energy determining the path of everything floating on the surface. Where currents wash shoreward, there are beaches, flotsam, and beached whales; where current does not wash toward the shore, there are no beaches, no flotsam, and no beached whales.
http://deafwale.com/seaquake_solution/