Size is everything in the world of the Giant Australian Cuttlefish

With males outnumbering females four to one, smaller cuttlefish stand little chance of getting close to a mate.

But they have been spotted changing colour to mimic females and hiding their masculine fourth arms.

Scientists say they were then able to trick their way past male consorts to make their move, often successfully.

Researchers led by Dr Roger Hanlon from the Marine Resources Centre in Massachusetts watched smaller male cuttlefish adopt the females' mottled skin pattern.

'Meeting under rocks'

"We found that female mimickers could successfully deceive the consort male and that they were able to position themselves near the female in 30 out of 62 attempts," he said.

Of the five males that tried to mate, one was rejected, one was unmasked by the "consort male", and three were successful.

Two of the three successfully fathered offspring with the female.

But there were risks attached. Some of the larger males got a little confused - researchers saw 41 attempts to mate with the fake females.

We found that female mimickers could successfully deceive the consort male and that they were able to position themselves near the female in 30 out of 62 attempts Dr Roger Hanlon

In a competitive dating environment, female giant Australian cuttlefish could afford to be choosy, rejecting 70% of mating attempts, said the researchers.

But smaller males also tried their luck by moving in while male consorts were fighting, or by "meeting females under rocks".

The author of the report, Paul Shaw, said: "It is very rare to be able to observe these events in the wild and be able to sample them. The small male mimics a female to fool the large males so he can get past them.

"They are actually disguising themselves to get past the males they couldn't beat in a fight. It seems to be a very successful strategy, and I don't know why a counter strategy doesn't exist in the large males."