I thought it was air at first, but seems to be a big ziploc bag. Just that when you say half empty... I don't know if Ziploc bags enable you to trap air as well.
Anyway, it could also be to the cold weather that we're having which I probably would think it is.
1 There was air in the bag!
2 They were placed in a cooler in the house as soon as they were put in the bag.
3 My car was parked across the street from K's house, so it took me all of 3 min. to get them into a nice warm car.
4 The cooler was cradled within the folds of my coat in the front passenger seat. The only turbulance I would imagine should have been a low swaying as I took turns.
Guess it just one of those things that we will never know the answer to.
i agree with ya... usually when i buy shrimp i throw ina few rubber bands so they can climb on and what not... a few times i didnt do it cause the lfs said no need and those few times the shrimps died... lucky it was still in the baggg so i drove back to the lfs and made him replace them and add rubber bands... no issues then... if they dont have rubber bands u can use bounty... lol good luck