They noted that the grass can absorb and control the spread of harmful wastewaters, like those from pig farms.

VOA: special.2010.02.09

And while they eat the grass, they may need guard animals to protect them from animals that would like to eat them.

VOA: special.2010.01.19

Hippopotamuses like to stand in the grass and eat most of the day.

VOA: special.2009.08.19