Why do hippos yawn?

FESCH.TV INFORMIERT:

You could believe a yawning hippo is drowsy or even cute, but when a hippo yawns it is a warning sign. A hippo yawn displays the jaws and long, sharp teeth to exhibit strength and ferocity.

Even a hippo’s sounds, which resemble a deep and demonic chuckle or laugh, is a warning and does not indicate a humorous situation. Conversations between hippo can travel great distances, from one pod to the next in a chain. Their honks, groans, and roars, among other things, express authority and claim territory.