What are some examples of commesalism?

Answer 1

Commensalism, which is a form of symbiosis in which neither party does the other much good or much harm, is rather rare and hard to declare. The usual example is that of the shark and the remora. But although the remora doesn't feed on the shark (which would make it a parasite), it does hamper the shark by increasing the drag on it.

If the remora helped the shark find its food, it might be in a case of mutualism, but it doesn't, so it's a "commensal" (the word means "at the same table") almost be default.