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WOODS HOLE, MA—For the giant Australian cuttlefish, mating is a complicated undertaking complete with fighting, sneaking, and deception. In this week's issue of the journal Nature, Marine Biological Laboratory (MBL) senior scientist Roger Hanlon and his colleagues demonstrate that for this species, deception while mating pays off.

Hanlon and his team present behavioral and genetic data demonstrating that small male cuttlefish that dramatically alter their appearance to look like females are highly successful in tricking their often larger male competitors and fertilizing the female's eggs. While the sexual mimicry that the cuttlefish employ has been widely reported in nature, this is the first time fertilization success in an animal using this strategy has been documented.

Hanlon and his colleagues studied the cuttlefish (Sepia apama) in a remote coastal area of the Australian outback. For ten days they painstakingly observed and filmed the intense mating competition between the females and their suitors, including large “guard” males, smaller “sneaker” males, who attempt to mate with females as the guard fights other males, and males who mimic the appearance of a female. In contrast to some other animals, whose ability to mimic is part of their genetic makeup, giant Australian cuttlefish use neural control to instantly change their skin patterning, posture, and tactics. According to Hanlon the cuttlefish can switch between a male and female appearance 10 to 15 times per minute. “In the blink of an eye they can pull out of it and go back to being a male,” he says.

Using DNA fingerprinting, Hanlon and his team found that the mimickers were successful in fertilizing females 60 percent of the time. The results, they say, are surprising since female cuttlefish of this species reject most mating attempts by any type of male 70 percent of the time. “This is not an easy behavior to study,” says Hanlon. “But we hope that our paper will engage other behavioral ecologists to go out and study mating systems of other animals to refute or support what we found.”