Marathon three hour sex sessions leave squid so exhausted they limp through the water for up to half an hour afterwards.
There is a reason for this – the long mating sessions help the southern dumpling squid ensure their genes are passed on.
The creatures also mate frequently throughout their short lives.
Octopussy: The long mating sessions help the southern dumpling squid ensure their genes are passed on
But it seems the mating sessions take their toll. The squid are so exhausted after sex they have to hide in the sand to escape predators.
Professor Amanda Franklin, of the University of Melbourne, said: ‘We found that after mating, both male and female dumpling squid took up to thirty minutes to recover to their previous swimming ability.
‘This suggested that the squid were suffering from temporary muscle fatigue.
‘We predict that during this phase of muscle fatigue, squid may hide in the sand to avoid predators until they have recovered,’ say the researchers
‘Our results were a little surprising as the degree of fatigue was similar in both genders even though mating looks more strenuous for males.
‘We predict that during this phase of muscle fatigue, squid may hide in the sand to avoid predators until they have recovered.
‘The cost to them in doing this of course is that they cannot forage for food or search for other mates at this time
‘Dumpling squid live for less than a year, and may engage in the energetic activity of mating many times within their short breeding period.
‘This reproductive strategy may have other costs to individuals besides energy loss and we have investigated this further by assessing the effect of mating on female lifespan.
‘We’re hoping to report the results of this experiment very soon.’
In order to pass on their genes, southern dumpling squid engage in up to three hours of mating with each partner, but this results in a reduced ability to swim for up to 30 minutes afterwards.
Male dumpling squid appear to initiate mating whenever the opportunity arises by grabbing the female from underneath and holding her in place while they have sex.
And both male and females can change colour from a sandy yellow to dark purple with green and orange highlights, as well as producing a cloud of ink as a decoy to help them escape from predators.
Dumpling squid can grow up to about 7cm long and live for less than a year, but make up for their short life by mating countless times in their short breeding period.
They are closely related to about ten bobtail squid species around the world, including the waters around Hawaii and the South China Sea.
Researchers were keen to understand the impact of such an extensive mating ritual because the energy used in copulation could reduce an animal’s survival by decreasing their ability to avoid predators and hunt for food.
They collected dumpling squid from St Leonards, south-eastern Australia, and tested their swimming endurance against a constant current of water.
The squid were then allowed to mate and their swimming ability was re-tested, with results showing it took them up to half an hour to return to their normal ability.
The Biology Letters study says the squid could have been suffering from temporary muscle fatigue and may hide from predators in this time.