Bottlenose dolphins 'smile' at their friends while they play together, study reveals

They're widely considered some of the most charismatic animals in the ocean. Now, it turns out bottlenose dolphins actually'smile' at each other while surfing, chasing and playfighting, according to a new study. Until now, little has been known about how the species - famed for their intelligence and playfulness - interact during playtime. But experts have finally revealed that these dolphins use the'open mouth' facial expression – comparable to a smile – to communicate during social play. The dolphins almost always use the facial expression when they are in their playmate's field of view, the researchers found, and playmates responded by'smiling' back a third of the time.