Imagine an alien with three hearts, blue blood and a doughnut shaped brain. In an instant it could become invisible, or switch on electrifying light shows. Then imagine this bizarre creature was real, and somehow connected to us.

"Cuttlefish are just are so different from anything that's familiar to us. When you dive with them and see all the things that they're capable of, you just can't help being drawn to them", says world authority Dr Mark Norman.

The undisputed masters of disguise, Dr. Norman reveals how cuttlefish can change their shape and colour to mimic their surroundings, intimidate their rivals or even hypnotize their prey.

The largest of all, the Giant Cuttlefish are usually shy creatures, but once a year they put on the biggest show of their lives. Gathering in their thousands off the South Australian coast, the pumped-up males compete for their right to mate. Fighting and dancing, they stop at nothing to outflash each other. Smaller males even resort to cross-dressing for their chance to get the girl.

Clearly, cuttlefish survive on their wits. And they share something with us - brainpower. Just as we have the biggest brains of all mammals, cuttlefish have the biggest brain to body ratio of all invertebrates. But does this mean they are actually intelligent?

In the U.S., comparative psychologist Dr. Jesse Purdy, and animal behaviourist Dr. Jean Boal, put their brainpower to the test. Can cuttlefish learn and remember complex tasks over time? They can, easily passing the first rungs of the IQ ladder. But cuttlefish could also hold an important key to our own intelligence - as Dr. Boal says: "Through cuttlefish we begin to understand what actually happens between our own ears."

And it's not just their remarkable brains that attract our attention. The most unusual member of the Brainy Bunch could hide a deadly secret. Travelling to Asia, Dr. Norman tracks down the strikingly colourful Flamboyant Cuttlefish, which prefers to walk, not swim. He suspects this tiny beauty might be toxic, and his tests will reveal if this attention seeker is the first deadly cuttlefish in the world.

This global adventure brings to the surface the spectacular pyrotechnics of these intriguing creatures, to discover just what goes on between their eyes and what they can teach us about our own brains.

CUTTLEFISH - The Brainy Bunch is produced by the award winning team of Gisela Kaufmann and Carsten Orlt of Kaufmann Productions.