He looks like something from a prehistoric age or a fantastic creation from Hollywood. But Hercules is very much living flesh and blood - as he proves every time he opens his gigantic mouth to roar. Part lion, part tiger, he is not just a big cat but a huge one,standing 10ft tall on his back legs. Called a liger, in reference to his crossbreed parentage, he is the largest of all the cat species.

He is the accidental result of two enormous big cats living close together at the Institute of Greatly Endangered and Rare Species, in Miami, Florida, and already dwarfs both his parents.

"Ligers are not something we planned on having," said institute owner Dr Bhagavan Antle. "We have lions and tigers living together in large enclosures and at first we had no idea how well one of the lion boys was getting along with a tiger girl, then lo and behold we had a liger."

50mph runner... Not only that, but he likes to swim, a feat unheard of among water-fearing lions. In the wild it is virtually impossible for lions and tigers to mate. Not only are they enemies likely to kill one another, but most lions are in Africa and most tigers in Asia. But incredible though he is, Hercules is not unique. Ligers have been bred in captivity, deliberately and accidentally, since shortly before World War II.

Today there are believed to be a handful of ligers around the world and a similar number of tigons, the product of a tiger father and lion mother. Tigons are smaller than ligers and take on more physical characteristics of the tiger.