How the animals escaped the tsunami

[Ivan Seeking]

It is widely reported that animals were generally able to anticipate the tsunami and seek higher ground. The exact mechanism for this is now a subject of debate. One expert believes that a warning or panic signal cascades through the animal populations ahead of the wave. Others suggest that hearing is the key, and still other explanations are found. Here is one report.

Wildlife officials in Sri Lanka have reported that, despite the loss of human life in the Asian disaster, there have been no recorded animal deaths. [continued]

http://news.bbc.co.uk/2/hi/south_asia/4136485.stm

 

[alpha_wolf]

If I recall correctly, one of the videos on the web show (among many other things) a bird flying away as the wave floods the coast. So at least that one didn't leave the area in advance...

 

[Astronuc]

Birds can get airborne fairly quickly, they simply go up. And there is no telling where the bird was just before it came into that area.

As for land animals - the could have heard the tsunami - something to which people are less sensitive. Also, elephants are very good at detecting vibrations in the ground, and they would have known something unusual was happening. Other animals could have taken cues from the elephants - as is the case on the plains of Africa and other wild places. Humans have long forgotten.

Incidentally, there was one island off the coast of Sumatra where the inhabitants evacuated the coastal areas for higher ground. No one was lost. Apparently they have passed down in oral history, the story of a major tsunami following an earthquake back in the 1800's. So some people do learn. But it is a shame that the entire nation did not share that experience. It could have saved about 100,000 lives.

 

[Kerrie]

what about the sea life being washed ashore? most of humanity are out of touch with nature. we have TV, radio, and internet to keep our minds focused away from nature. that is all animals have however, and living and dealing with the natural world tends to shift your focus on just that. instead of being naturally intune, we have devices and machinery to do that for us, which in my book is far less advanced then the animal's intuition.

 

[Sho'Nuff]

Birds can get airborne fairly quickly, they simply go up. And there is no telling where the bird was just before it came into that area.

Animals also respond to each other, in documentaries you ofthen see herds running before a lion is in range because of birds flying up

 

[tumor]

Dogs for sure can hear higher frequenciess than we humans can't,maybe those big waves generated frequenciess only animals could detect and thus up on hearing them they were frightened and ran away from the shore?
I don't know if other animals have simmillar hearing frequency as dogs have, propably not,but if dogs were running away other animals saw something unusal in this and did the same thing.
That is just my take on this.

 

[matthyaouw]

what about the sea life being washed ashore?

If they were to sense it coming, many species' reactions may be to head for the shallows in case of danger, which in this case didn't work out so well. (I'm merely speculating. Don't take my word for it)

 

[alpha_wolf]

what about the sea life being washed ashore?

If they were to sense it coming, many species' reactions may be to head for the shallows in case of danger, which in this case didn't work out so well. (I'm merely speculating. Don't take my word for it)

Hmm... this raises an interesting question. Before the tsunami reaches the coastal shelf, it travels as a pressure wave inside the water. How would that pressure wave affect the sealife that gets in its path? Is it strong enough to injure/kill some of them?

 

[chroot]

alpha_wolf,

A tsunami is not a pressure (longitudinal) wave; it is a transverse wave on the surface of the water. The sealife will be tossed up and down a bit as the wave passes (the violence of the tossing decreasing with depth), but probably would be otherwise unaffected.

- Warren

 

[Moonbear]

I wonder if the animals really know what they are fleeing, or just sense vibrations and run away from the direction they are coming from, the same they would if anything were approaching from that direction large enough to cause the ground to vibrate. Interestingly, for seabirds, they'd have been better off staying at sea. Did they? Animals also communicate pretty well and have "danger/distress" calls. When they hear these, they don't stop to gawk like people do, they run away from the danger. And when beaches are crowded with people, how many other animals are going to be around there anyway? It may be that the people already scared them inland whether there was a Tsunami coming or not.

 

[DocToxyn]

Hmm... this raises an interesting question. Before the tsunami reaches the coastal shelf, it travels as a pressure wave inside the water. How would that pressure wave affect the sealife that gets in its path? Is it strong enough to injure/kill some of them?

The only footage I saw of animal casualties was of an octopus washed up into the rubble. If I remember my oceanography well enough a wave in deep water moves object in a circular fashion, with decreasing diameter of said circle the further down in the water column the object is. No forceful breaking of the wave is observed until the wave reaches a point at which it encounters the ocean floor at a depth of (I think) 1/2 the wavelength. Then the waves begins to pile up since the seabed is slowing them down and they will eventually break. Since tsunami-type waves have very long wavelengths the waves builds very far out and reach extreme heights, this is when most destructive damage would occur as witnessed by recent events. My suspicion is that most open-water marine life (those away from the breaking point) went unscathed. Someone please correct me if I'm wrong.

 

[Moonbear]

My suspicion is that most open-water marine life (those away from the breaking point) went unscathed.

That would be my expectation as well. Perhaps it would be experienced on the sea floor as a swift current would be experienced. It wouldn't involve much, if any, turbulence until it hit shallow shorelines. Of course the sea-life along the fault line of the earthquake producing the tsunami would be affected by the massive shift in the sea floor there. I don't know about fish in the area, but other critters, like sponges and sea anemones, and plant life that can't quickly get away at the first signs of tremors would have been caught in the earthquake. On the other hand, everything that was washed back into the water from land with the recession of the wave is probably wreaking havoc on the local marine environment. Considering that fishing is the livelihood of many of the communities devastated by the tsunamis, the effects on the marine environment will lead to continued problems for those people even once the initial loss to life is dealt with (understandably, with human death tolls into the 6-figures, the media focus isn't on the environmental impact of a disaster arising from natural causes).

 

[Ivan Seeking]

a related paper

Earthquake Prediction by Animals: Evolution and Sensory Perception
Abstract Animals living within seismically active regions are subjected episodically to intense ground shaking that can kill individuals through burrow collapse, egg destruction, and tsunami action. Although anecdotal and retrospective reports of animal behavior suggest that although many organisms may be able to detect an impending seismic event, no plausible scenario has been presented yet through which accounts for the evolution of such behaviors. The evolutionary mechanism of xaptation
can do this in a two-step process. The first step is to evolve a vibrationtriggered early warning response which would act in the short time interval between the arrival of P and S waves. Anecdotal evidence suggests this response already exists. Then if precursory stimuli also exist, similar evolutionary processes can link an animal’s perception of these stimuli to its P-wave triggered response, yielding an earthquake predictive behavior. A population-genetic model indicates that such a seismic-escape response system can be maintained against random mutations as a result of episodic selection that operates with time scales comparable to that of strong seismic events. Hence, additional understanding of possible earthquake precursors that are presently outside the realm of seismology might be gleaned from the study of animal behavior, sensory physiology, and genetics. A brief review of possible seismic precursors suggests that tilt, hygroreception (humidity), electric, and magnetic sensory systems in animals could be linked into a seismic escape behavioral system. Several testable predictions of this analysis are discussed, and it is recommended that additional magnetic, electrical, tilt, and hygro-sensors be incorporated into dense monitoring networks in seismically active regions. [continued]

http://www.gps.caltech.edu/~jkirschvink/pdfs/earthquakeprediction.pdf

 

[Monique]

I found the story intruiging that sea gypsies were able to seek high grounds, since the elders fore-warned that when water retreives quickly along the shoreline, it will come back with a massive force. The sea gypsies sought shelter in a temple up a high mountain and were saved.