Researchers have unearthed the secrets of how hippopotamuses communicate, and it can get pretty messy.
A team of European-based scientists discovered the hippos can recognise each others' voices.
There can be friendly "wheeze honk" banter between friends but it's different when strangers join in - often resulting in a spray of angry dung to mark territory.
Corin Dann spoke to Lisbon-based biology professor Paulo Fonseca who explained the hippo's different sounds.
