Jaime says ...

1.       The majority of the devastation caused by the Sumatra and Tohoku (the region of Japan most seriously affected by the temblor) earthquakes was caused by the attendant tsunami, which in both instances was basically caused by the edge of the tectonic plate ‘pinging upwards’ as the stress was released. This pushes the water column above the thrust upwards, resulting in a wave.

The wave is so destructive because it has a high amplitude and long wavelength. It’s often barely noticeable in the open ocean as the amplitude of the wave is not as great as the depth of the water column. When the water gets shallower, though, the sea floor reflects the wave back earlier, so the energy has nowhere to go. The amplitude of the wave is deflected upwards, causing it to rear up. The long wavelength ensures that there are millions – possibly billions – of gallons of water pushed up behind the crest which all follows the wavefront inland. This is why it’s so destructive on coastal areas.

Unless whales happened to be close to shore, I don’t think they would suffer any ill-effects – a wave is actually a circular motion of the water, so they might be somewhat confused for a few seconds as they are pushed in a wide circle. As for other marine life, obviously coastal fish and other sea life close to shore would be pushed inland and come into contact with very dirty, muddy water, with implications for their survival. Coral and other sedentary organisms would have to cope with the sheer amount of energy in the wave as it pushed strongly in one direction for several minutes, and then deal with the sludge, and possibly pollutants, flowing in the other direction as the wave recedes

2.       Marine creatures in the deep ocean probably wouldn’t be largely affected by earthquakes, since not much in the way of tremors is felt at the source of a quake. Same with tsunamis; in the open ocean, tsunami waves are just a couple feet tall at most. They get large in shallow water.

  Marine creatures who are more likely to get affected by things like these are those living    in intertidal zones (whose habitats would be washed away by a tsunami) or if buildings or something fell into the water and damaged their habitat that way.