Hippos and buffalos share often the shores of the lakes and rivers. They tolerate each other, although both belong to the most aggressive African animals. The water cools off and the mud protects against the parasites.
The parts of the body not covered by water or mud are the hunting area for the oxpeckers. These birds specialize to eat parasites such as ticks and lice clinging to the skin of large animals. This relationship isn't perfectly. The oxpeckers keep wounds open to feed on blood, pus and any parasites attracted to the gore. The birds also rip mouthfuls of hair from mammals to line their nests. No wonder, that some animals e.g. elephants are particularly intolerant of these birds.
The hippos are freed from parasites even under the water. There are some specialized kinds of fish performing this job.
