Fatties are ambush hunters like the trapdoor spider. Apparently passive and immobile, these terrestrial cetaceans can move surprisingly fast if one puts a cake or the last slice of pizza too close to them. I suspect that the remote ancestors of these human mega-fauna lived in shallow caves in a state of semi-hibernation, only to swarm out in a mass of undulating, flopping, blobbiness to seize any creature that was unfortunate to come within their range and consume it whole accompanied by a symphony of obscene, wet, ingestion noises. It is likely that they would simultaneously take the opportunity to release vast accumulated gaseous toxins through their rear vents as they ingested their prey through their forward ones, an eating practice that persists, virtually unchanged, to this day.