used to watch my uncle put them straight in the pot....thoguht that the amount they struggle would be enough to indicate its a pretty painful way to go. funny that we would need a paper to figure this out. have always found icing first, or drowning to work much better for me, but even this probably would be pretty unpleasant. they are so armored i havent really been able to figure out a better way to dispatch them quickly though...

 I've allways Iki'd them, poke the spike in under the back end of the carapace in the midline all the way to in between the two horns. Pretty instant

 Put to sleep in the freezer for me. 

Some of the social media comments are entertaining. 

Out of pot straight in ice slurry . Instant

As above..sea water ice slurry is a must straight out of the water.

See so many pics with people using crates and eski with no ice.

Maybe it's me but find the meat peels out of the shell so much easier.

 There are studys out there that say plants are sentient. Theres some cool experiments they did to test it.   Id say even those human robots that are produced could be classed as sentient.

  I believe its true but you do what you can to minimise discomfort for what you kill.