Diver saves a turtle's life and is repaid the kindness

Can animals express gratitude? Most pet owners believe they can and this video suggests that saying "thank you" isn't uniquely human.

While spear fishing for tuna off Mexico's coast, Cameron Dietrich and Colin Sutton happen upon this sea turtle in trouble. Dietrich dives in and goes to work untangling the rope -- possibly part of a fishing net -- from around the turtle's flipper.

Once free, the sea turtle turns and begins to swim away. But then, an incredible thing happens. As Sutton continues to capture the scene with his go-pro camera, the turtle circles back. And swims up face to face with Dietrich, allowing the diver to hold him.

Is this turtle-speak for "thank you"? It could be. The World Wildlife Fund says fishing gear is the greatest threat to endangered sea turtles like loggerheads, green turtles and leather backs.