DOLPHINS' well-known smarts appear to have led them to drugs.

The brainy mammals have been caught on camera chewing on puffer fish that protect themselves by releasing a nerve toxin which, in low doses, appears to have a narcotic effect on the dolphins, according to the Sunday Times.

The remarkable footage will be shown as part of the BBC series Dolphins: Spy in the Pod, which uses remote-controlled underwater cameras to film dolphins up close.

The two-part series, which begins in the UK on Thursday, includes a segment showing dolphins deliberately passing around puffer fish in an apparent effort to milk them of their defence toxins.

"This was a case of young dolphins purposefully experimenting with something we know to be intoxicating," said Rob Pilley, a zoologist who worked as a producer on the series.

"After chewing the puffer and gently passing it round, they began acting most peculiarly, hanging around with their noses at the surface as if fascinated by their own reflection."

Mr Pilley said that the dolphins treated the puffer fish differently to their regular prey, which they usually rip apart.

And like any experienced drug user, dolphins appear to know their product.

"The dolphins were specifically going for the puffers and deliberately handling them with care. Dolphins seem to be experts on how to prepare puffers and how to handle them."