I semi-crushed an ant and then dropped it in a puddle of water. For about 30 seconds it spun in a?

I am more curious as to why you did semi-crush an ant and then drop it into a puddle of water, nevertheless, my best bet is that the ants natural reflex is to 'run' away and is therefore kicking/thrusting around - the reason it is circling in a circle may be that after you semi-crushed them they lost the ability to use some limbs; at a high speed I do not know why! I would not take my answer as a 100% accurate and I am probably incorrect as I do not specialise in animals/insects. I hope I helped.