Dolphins rank among the most intelligent animals, and scientists say some have shown that intelligence in surprising ways.
In footage made for a new documentary, young dolphins carefully handled a species of puffer fish that can emit a nerve toxin if disturbed.
While large quantities of this toxin can kill, small amounts are known to have a narcotic effect.
The dolphins appeared to have learned how to make the fish release just enough of the toxin.
They gently chewed the puffer and passed it around, then entered what looked like a trance-like state.
The behaviour was filmed for the series Dolphins: Spy in the Pod, produced for BBC One by wildlife filmmaker John Downer.
Rob Pilley, a zoologist and producer on the series, told the Sunday Times: “This was a case of young dolphins purposely experimenting with something we know to be intoxicating.
After chewing the puffer gently and passing it round, they began acting most peculiarly, hanging around with their noses at the surface as if fascinated by their own reflection.
It reminded us of that craze a few years ago when people started licking toads to get a buzz, especially the way they hung there in a daze afterwards. It was the most extraordinary thing to see.”
The filmmakers used hidden cameras disguised as turtles, fish and squid to record 900 hours of footage showing dolphins in the wild.
The scenes of dolphins handling puffer fish will appear in the series’ second episode, which begins on Thursday.
Downer has produced several programmes using similar spy-camera methods. Previous titles include Penguins: Spy in the Huddle narrated by David Tennant, Elephants: Spy in the Herd with David Attenborough, and Lions: Spy in the Den.
Downer said: “The spy creatures were designed to infiltrate the dolphins’ hidden lives by looking like the marine creatures a dolphin might encounter in their everyday lives.”