Bottlenose Dolphins

Two bottlenose dolphins leap in unison off Long Beach, California, their beaks and dorsal fins catching the soft light as spray falls away behind them. Despite the tight coordination on display, these dolphins live in what biologists call a fission-fusion society, with companions constantly joining and parting. Yet within that shifting crowd, some bonds last for years, and each animal carries a learned "signature whistle" that works much like a name. A duo leaping this closely together often marks that kind of stable, long-term relationship.