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Wednesday, 21 September 2011

Light shed on bisexual and promiscuous deep-sea squid

 A lot of weird stuff happens when nobody is looking and that includes under the ocean. Now, recent underwater camera footage has revealed that the deep-sea squid is both promiscuous and bisexual. Scientists have gained a rare glimpse into the sex life of the mysterious deep-sea squid after analysing footage taken by underwater vehicles, US researchers have found that this rarely seen creature will often engage in same-sex mating.

Octopoteuthis deletron (MBARI)

They believe this is because encounters with potential mates in the dark depths are rare, and the squid may be unable to tell the sexes apart. The study is published in the Royal Society journal Biology Letters. The researchers looked at video footage taken over 20 years by Remotely Operated Vehicles (ROVs), most of which was recorded in the Monterey Submarine Canyon, off the coast of California.

The species that was observed is called Octopoteuthis deletron, a tentacled beast that measures about 12cm-long (5in), with impressive hook-lined arms. It was recorded between depths of 400m and 800m (1,300-2,600ft). Until now, little was known about this creature's sex life, apart from the fact that the male uses a long, penis-like organ to deposit spermatophores, complex structures containing millions of sperm, onto a female, which are then absorbed into her tissue.

But by studying footage of this deep-sea squid, they were able to find out much more. For example, they will indiscriminately inseminate other squid. Lead author Hendrik Hoving, from the Monterey Bay Aquarium Research Institute (MBARI), explained: "We did not observe two animals mating, but we found evidence of mating - sperm packages on males and females.Going through hours of video, we found that both males and females carry sperm packages."

Octopoteuthis deletron (MBARI)
The sperm packages can be seen as white dots on the the dorsal arms of this female
"As the locations of sperm packages were similar in both sexes, we concluded that males mate with males and females."

The finding surprised the team, said Dr Hoving. The researchers found equal numbers of female and male squid that had had sperm packages deposited on them, indicating that same-sex mating was as frequent as encounters between squid of the opposite sex. The number of sperm packages that had been deposited also suggested that these animals were promiscuous, the researchers said. This unusual behaviour, they said, may be explained by the fact the squid is boosting its chances of success

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