I thought people may like this little tale - interspecies stuff is central to many a twee tale, but the language thing is facinating.

A baby hippo rescued after floods in Kenya in January befriended a 100-year-old tortoise in Kenya. The one-year-old hippo calf christened Owen was found alone and dehydrated by wildlife rangers near the Indian Ocean. He was placed in an enclosure at a wildlife sanctuary in the coastal city of Mombassa and befriended a male tortoise of a similar colour. According to a park official, they sleep together, eat together and "have become inseparable".

"Since Owen arrived on the 27 December, the tortoise behaves like a mother to it," Haller Park tourism manager Pauline Kimoti told the BBC News website.
"The hippo follows the tortoise around and licks his face," she said.

The tortoise is named Mzee, which is Swahili for old man.

In an extraordinary update to this news story it seems that there is a surprising level of communication between the two animals. They have been heard ‘speaking’ to each other. There is a ‘whine’ that is made by hippos but has been rarely heard by observers. It is thought to be a sound made by young hippos to their mothers or used as sign of submission. Both Owen and Mzee have been heard to make this sound and it is beautifully replicated in the news story:
http://www.bbc.co.uk/worldservice/programmes/worldtoday/news/story/2006/02/060212_wt_select_week_7.shtml
As well as this astonishing example of inter-species oral communication, Owen and Mzee have been observed communicating a desire for a stroll through a series of nudges and bites to Owen’s tail and guidance of direction through nips of Mzee’s left or right feet.

Unsurprisingly, scientists are showing a great deal of interest towards this pair.