Do animals commit suicide?

Despite the familiar myth of lemmings throwing themselves off cliffs, this seems to be a rare phenomenon. There are no real clear answers to this question.

It has been reported that dolphins in captivity have done it (one purportedly battered itself to death and soon after its companion did the same). Altruism that leads to death among animals is quite common, for instance, common octopi look after their young and fail to feed themselves sometimes to the point of death, and some spiders are devoured by their young.

There are some parasites that seem to cause suicides in their host, in somewhat odd ways, for example the parasite Toxoplasma gondii makes rats become unafraid of cats.. thus, they die. Some bumblebee parasites make the bee dive into ponds.

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^{some help from sciencenet.org.uk}

My father happened to do his military service (in Greece, like in many other European countries, military service is compulsory) when the Turks invaded Cyprus in 1974, so naturally, there was also a great military stirring at the time in Greece.

So, to the point. The soldiers, during the endless time of waiting and waiting in the hoods which were full of scorpions, these little arthropods with the deadly sting, the soldiers I was saying, highly under stress because of an imminent war with Turkey, they used to kill the scorpions and they had observed the following interesting phenomenon.

They would spill some gasoline around a scorpion but not on the scorpion, and they would put the gasoline ring on fire. The scorpion could not escape because these animals are very afraid of fire, and after some time of circling around the ring of fire trying to find a way to escape, the scorpion would bite itself with its own sting causing its death after about one minute. I guess this is clearly a case of an animal deliberately committing suicide.

--update: The wu below speaks about scorpions not affected by their own poison and suggest that they die from the heat. First of all, scorpion's poison has neurotoxins which I find highly unlikely not to be able to affect its neural system. Second, the ring of fire was large enough in diameter so as not to kill the scorpion with its heat...

Regarding the notion scorpions commit suicide when surrounded by inescapable flame, this is one of those legends akin to the lemming suicide myth.

It's been proven scorpions are not affected by their own poison. Scorpions do, however, really, really hate heat and fire and succumb very easily. Fire and high heat causes them great panic and causes them to flail about with their tail, stinging at everything. They no doubt sometimes land a blow or two on themselves before kicking from the heat. Hence, it would appear a scorpion surrounded by fire stings itself to death but this is not the case.

Sources:

http://99.1911encyclopedia.org/S/SC/SCORPION.htm
http://www.bizarremag.com/ask_bizarre.php?id=208