The egyptian plover is a bird best known for its symbiotic relationship with what host animal?

Nile crocodile

Explanation:

The Egyptian plover is a small bird with a very unusual friend in the animal kingdom. This bird actually has a symbiotic relationship with the Nile crocodile. It may seem very odd relationship, but it is one that works excellently for both sides. The crocodiles have sharp set of teeth, but they have spaces between them and can not move their jaws sideways. Because of this, very often there's meat stuck between the teeth of the crocodiles, and this is when the Egyptian plover comes on the scene. This little bird actually gets into the open mouth of the crocodiles, picking up the pieces of meat that have stuck between their teeth, and then continuing with its mission. The crocodiles do not try to eat this bird, but instead they stand still while it does its job. The relationship is beneficial for both sides, as the crocodiles have their own personal ''dentist'', while the plover gets free food.