These bizarre jellyfish-like beings is what aliens would look like, if they exist, a British scientist has said.

This is what evolution might have come up with on a world such as Saturn's moon Titan, Dr Maggie Alderin-Pocock believes.

She envisages creatures that float through clouds of methane, scooping chemical nutrients into their gaping mouths.

The aliens keep themselves aloft by means of dangling onion-like buoyancy bags, and communicate with pulses of light.

Her aliens would probably die on Earth, finding the damp oxygenated atmosphere lethally corrosive. Equally, humans would not survive on Titan.

Based on the latest discoveries of star-orbiting planets, she also believes as many as four intelligent extra-terrestrial civilisations could exist in our galaxy, the Milky Way.

But they are so far away it is unlikely we will ever meet them.

Dr Alderin-Pocock presents Do We Really Need the Moon on TV channel Eden today at 7pm.

Our imaginations are naturally constrained by what we see around us, and the conventional wisdom has been that life needs water and is carbon-based. "But some researchers are doing exciting work, playing with ideas such as silicon-based life forms. "Silicon is just below carbon in the periodic table, has some chemical similarities, and is widely available in the universe. "So perhaps we could imagine similar instructions to DNA but with silicon. "Maybe life doesn't have to resemble anything like DNA at all."