Dolphin ‘smiles’ may truly be a sign of playfulness

Captive dolphins are more likely to make an open-mouthed expression when their playmate can see them and they often reciprocate, hinting that it is a form of visual communication Captive dolphins are more likely to make an open-mouthed expression when their playmate can see them and they often reciprocate, hinting that it is a form of visual communication  New Scientist – News