The pink dolphins of Hong Kong

The river delta which runs behind Hong Kong's busy international airport is home to around 100 increasingly rare, and baffling, pink dolphins.

The Indo-Pacific humpback dolphin is found in seas from China to South Africa, and the Western Pacific.

But it's only in the Peal River delta around Hong Kong where they're pink - and scientists aren't sure why.

There's also concern about their dwindling numbers. CNN reports.