Using cameras hidden behind the eyes of realistic sea animal robots, the undersea world of dolphins has been revealed. (Photo: John Downer Productions / Rhonda J. Miller)

Robot dolphins, a robot tuna and a robot sea turtle fitted with HD cameras have filmed close encounters with real dolphins to capture their lives and reveal their mysteries to landlubbers watching warm and dry from their sofas.

"Swimming alongside some of the most captivating and clever animals on the planet, these new spies are always on the move — catching the waves with surfing bottlenose dolphins and speeding with a megapod of spinner dolphins," according to BBC Media about its program "Dolphins: Spy In the Pod" to air Jan. 2

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"Our spy creatures had to keep pace with fast-moving dolphins, often out in the deep ocean," said wildlife filmmaker John Downer, producer of the two-part TV series for BBC One. "The dolphins were very curious about their new neighbors and allowed them into their lives."

The robotic sea animals are meant to trick the dolphins with the cameras lenses hidden inside their eyes, according to Wetpixel, the underwater photography magazine. Downer's documentary has never-before filmed behavior taken by the underwater robot entourage that also includes a nautilus and a ray.

Each radio-controlled sea animal is packed with high tech equipment. The film has one sequence shot off the coast of Costa Rica in which the robotic Spy Dolphin is guided by experts in a high-speed inflatable boat. The dolphin robot easily keeps pace with the real-life spinner dolphins, which can cover 250 miles a day. When the spinner dolphins dive underwater, the filming is transferred from Spy Dolphin to the superfast robotic Spy Tuna, according to the Mirror. In the depths of the ocean, the tuna robot caught up with a megapod containing thousands of dolphins and filmed the spectacle.

Downer's most unusual robotic sea animal is the Spy Nautilus, which is based on a brightly-colored mollusk. Odd though it may appear, Spy Nautius was welcomed by a family of bottlenose dolphins in the Indian Ocean, which surrounded the robot creature. That gave the camera in the robot Nautilus' eyes a rare close-up of a tiny, five-day-old calf, still wrinkled from birth, the Mirror reported.

The collection of motorized sea animals captured a variety of fascinating footage. The robot Spy Turtle filmed bottlenose dolphins surfing the waves. Spy Dolphin and Spy Ray got lucky off the Florida coast and were able to film a pod of dolphins stirring up mud to encircle their prey — a mullet.

Most of the behavior captured has never been seen before, according to the MIrror, including dolphins forming alliances with stingrays and other fish to hunt together for food.