Dumpling squid slowed down by sex

18 July 2012 Last updated at 08:37 By Ella Davies Reporter, BBC Nature

Promiscuous dumpling squid take 30 minutes to return to normal swimming speed after mating, say scientists.

The short-lived cephalopods, named for their rotund shape, are known to mate with as many partners as possible.

Researchers studying this behaviour found that swimming endurance was halved after mating for both sexes.

They described mating as "costly" for the squid because it reduced the energy available for avoiding predators and feeding.

The study of wild-caught squid is published in the Royal Society journal Biology Letters.

"The squid mate for up to three hours and the male must physically restrain the female during this time," said researcher Amanda Franklin from the University of Melbourne, Australia.

"It was exciting for us to show that this affects their physical abilities after mating because this has not been shown before."

Dumpling squid (Euprymna tasmanica) are members of the bobtail squid family and found along the southern coast of Australia.

They live for less than a year and spend their last few months mating. During this time the squid mate with as many partners as possible.

Females lay clutches of eggs several days after mating but they are also able to store sperm in order to fertilise eggs at a much later date.

Studying wild-caught squid, scientists found that males were energetic during mating; changing colour, squirting ink and pumping jets of water into the females mantle (the main body).

Although they were much less active, females were equally worn out by the activity. Scientists suggest this may be due to the way the males physically restrain them by gripping their body, reducing their access to oxygen.

Continue reading the main story

Sex life of a squid

• Super-sized squid: How male deep-sea squid use their huge penises to inject packages of sperm into females' bodies
• Colourful courtship: See male Australian squid dance and change colour to attract a mate
• Deep-sea sex: Elusive squid species Octopoteuthis deletron often engage in same-sex mating and display promiscuous behaviour
• "Sneaker" squid: Smaller male Bleeker's squid have bigger sperm and use different mating techniques to their larger counterparts

"We decided to study these charismatic squid because very little is known about them and cephalopods have very interesting mating systems, from sexual cannibalism to multiple mating and long mating durations," said Ms Franklin.

She suggested that the team's findings could give insights into why certain reproductive behaviours have evolved.

"[The energetic cost of sex] is likely to affect how an animal behaves after mating and may also influence how often an individual will mate," she told BBC Nature.

Source: http://www.bbc.co.uk/nature/18861785

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