Female impersonation as an alternative reproductive strategy in giant cuttlefish

Out of all the animals, the cephalopods possess an unrivalled ability to ch ange their shape and body patterns. Our observations of giant cuttlefish (S epia apama) suggest this ability has allowed them to evolve alternative mat ing strategies in which males can switch between the appearance of a female and that of a male in order to foil the guarding attempts of larger males. At a mass breeding aggregation in South Australia, we repeatedly observed single small males accompanying mating pairs. While doing so, the small mal e assumed the body shape and patterns of a female. Such males were never at tacked by the larger mate-guarding male. On more than 20 occasions, when th e larger male was distracted by another male intruder, these small males, p reviously indistinguishable from a female, were observed to change body pat tern and behaviour to that of a male in mating display These small males th en attempted to mate with the female, often with success. This potential fo r dynamic sexual mimicry may have played a part in driving the evolution of the remarkable powers of colour and shape transformation which characteriz e the cephalopods.