Actually it's not that easy
How long is the crayfish? Does it have both claws? What gender is it? Weight? Did it go in head first or tail first or perhaps sideways? Was it a soft shell? What was the temperature of the water? Was it covered in slime,fishing line or other debris? Night or day? Sunny or precip/cloudy? How large was the Bass? Did it have any stomach problems/ulcers/pollution problems?How many crayfish were already in there? You see Goose this could just go on and on...Hern didn't provide necessary info to calculate an answer
He's looking for 2 minutes 37 seconds which would be the average time to die for an average crayfish eaten by an average Bass with an empty stomach on a 70 degree day with full sun and 65 degree water..............good question Hern hopes this clears it up a little for you.......