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 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 its mouth shut and have the plover for a snack.