Crocodiles are rather messy eaters. Their jaws can open and close, but can not move from side to side, neither can they use their tongues to propel food around their mouths. The arrangement of their teeth—still in prehistoric form—does not allow them to chew. All of this simply means that the crocodile is a biter, tearer and gulper of food. Such practices mean a lot of food gets caught in a crocodile's teeth, attracting parasites, bacteria and leeches.
You'd think that would lead to one sore mouth, and it would if not for the Egyptian Plover. Crocodiles invite the plover over for a meal by beaching themselves, opening their mouths wide and remaining very still. The plover will approach and actually enter the croc's mouth. Once there, the bird will set about gobbling food scraps and parasites. Another win/win.
This great photo was taken by Wally Irwin.