when i was testing 1.8 for all of the new features i spawned an endermite, a gaurdian on land, and 4 rabbits i noticed that all 3 of them were flying as though they were in an invisable anti gravity field you can still see the rabbit shadows as though they were still on the ground sadly when i noticed tht this might be a bug i only took a picture of a rabbit but that should be enough evidence for you guys thank you as you can also see a pig was on the ground the whole time so i think it only happens with newer mobs