New research uncovers deceptive courtship in Sydney Harbour

4 July 2012

Researchers have uncovered a unique behaviour in the mourning cuttlefish (Sepia plangon). When courting, the male cuttlefish will display both male and female colours simultaneously to cleverly seduce the female while at the same time hoodwinking rival males.

The deceptive male positions himself between the female and the rival male. Showing his true male colours towards the female to woo her, he will at the same time mimic female colours to the rival male to disguise the courtship.

Researchers discovered the behaviour while observing the various social groups of cuttlefish that reside in Sydney Harbour. They found only when a group comprised two males and one female did the males choose to employ the deceptive behaviour. In this context males were deceptive 39% of the time.

Researcher Martin Garwood says one reason this tactic can be explained is that for cuttlefish seduction can’t be rushed. “It can take a while to win the female’s heart. By deceiving the rival male the deceptive male can get the job done without being interrupted or challenged,” says Garwood.

Cuttlefish are part of the phylum Mollusca whose closest relatives are snails and slugs, however there is a wide gap in intelligence levels between them and their relatives. This new research supports the theory that having a complex social life may be key to evolving high levels of intelligence. “The use of complex deception in such a specific scenario indicates a high level of sophisticated intelligence in cuttlefish,” says Garwood.

Living in complex social groups requires intelligence to succeed. This is known as the social brain hypothesis and is also often used to explain human intelligence.

“Only the smartest reproduce, and intelligence is then passed on to the next generation. So although cuttlefish seem a world apart from humans, perhaps we have more in common than we may have previously thought,” Garwood explains.

This research will be published in the Royal Society journal Biology Letters on the 4th of July 2012 and is titled ‘It pays to cheat: tactical deception in a cephalopod social signalling system’ authored by Culum Brown, Martin Garwood and Jane Williamson.

Filed under: Research Science & nature