Reporter 438, 26 July 1999

Cuttlefish capers

Male cuttlefish can turn transvestite to sneak past rival males guarding their mates according to a new study carried out by a biology researcher.

The crafty cross-dresser then regains his masculine physique in time to woo the female, but can quickly disguise himself again to avoid discovery, should the spurned (and usually larger) male return unexpectedly.

Research fellow Tom Tregenza has recently returned to the University from Australia, where he studied the underwater deception with colleagues from Queensland and Tasmania.

Cuttlefish usually use this ability to change shape and appearance to evade predators, though they also transform themselves for elaborate courtship rituals.

Taking this one stage further, the female-impersonating giant cuttlefish males retract the tell-tale webs that fringe their arms, as well as adopting the female colours and pattern.

Dr Tregenza said that though other male animals are able to mimic females, none can switch forms so easily. "Once youíve got those abilities, they start to come into play for something else," he said.

The gender-bending disguise is so convincing, it even baffled the watching biologists. "We have to follow them and see when they change back," said Dr Tregenza.

The full reasons for the shifty behaviour are unclear, though they are usually performed by the smaller males. "The larger males donít need to - they can win contests with other males," he said. The study was published in the Proceedings of the Royal Society.

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