You've probably seen - presumably on TV - Nile crocs Crocodylus niloticus interacting with Common hippos Hippopotamus amphibius (if you've seen it in real life, lucky you). By and large the two seem to keep apart. Having said that, there are certainly photos of the two sharing the same sandbanks. And then there are those instances of hippos scaring crocs away from carcasses, the weird reports of hippos mouthing and chewing the backs and tails of resting crocodiles, and those cases where crocodiles have been seen to walk or run across hippos' backs.