One of the most visually surprising examples of symbiosis occurs between the fearsome African crocodile and the small plover bird. When a plover is nearby, a crocodile will open its long, sharp-toothed jaws to invite it inside. You might assume that the plover would quickly reject this invitation and fly off. Yet surprisingly, the plover does hop inside. Perhaps even more amazingly, the crocodile, normally known for its aggression, does not snap and have the plover for a snack. Instead, it remains still, not closing its mouth until the plover leaves. How can this strange behavior be explained? The answer is symbiosis . The plover picks out all the small, harmful animals attached to the croc's teeth. In doing so, it cleans the crocodile's teeth, which prevents the croc from getting infections. Because the crocodile can not clean its own teeth, it depends on the plover to perform this service. In return, the crocodile provides an easy meal for the plover.