Hippopotamus
Behaviour and life history
Hippos appear to communicate vocally, through grunts and bellows, and they may practice echolocation, but the purpose of these vocalisations is currently unknown. Hippos have the unique ability to hold their heads partially above the water and send out a cry that travels through both water and air; individuals respond above and under water. Hippos will also express threat and alarm with exhalations.
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