For a squid, mating can take up to three hours, and the resulting energy losses could put the animal at a disadvantage around predators and reduce foraging opportunities.

Credit: M. NORMAN/MUSEUM VICTORIA

Amanda Franklin and her colleagues at the University of Melbourne in Victoria, Australia, collected wild dumpling squid (Euprymna tasmanica; mating male and female pictured). They tested the creatures' swimming endurance in a tank with a constant current, before and after the squid mated. Mating halved the time taken for males and females to become exhausted, but both regained their energy within 30 minutes of copulation.

Knowing this cost could contribute to a better understanding of the evolution of reproductive behaviours, such as promiscuity, in squid, the researchers say.

Biol. Lett. http://dx.doi.org/10.1098/rsbl.2012.0556 (2012)