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Squid sex video penetrates long-standing mysteries of the deep-sea deed

January 10, 2013 1:19pm
An "unusual but intimate" sex video has aroused the interest of scientists who are studying how deep-sea squid mate.
 
The researchers filmed the act of two deep-sea squid using a remote-controlled sub some 1,400 meters down in the Gulf of Mexico, the Smithsonian Institute reported.
 

"(In the video, the) two deep-sea squid (species: Pholidoteuthis adami) maintained their unusual but intimate position. The male was upside down on top of the hovering female, gripping her firmly; their bodies parallel but pointing in opposite directions," the Smithsonian said.
 
Connecting the two was the white “terminal organ” or penis of the male, extending out through the male’s funnel.
 
The researchers said possible reasons for the odd mating positions in this squid species include preventing the female from grabbing and eating the male, as well as improving mobility of the terminal organ.
 
“People have guessed how the terminal organ was used, but in some ways they guessed wrong,” said Michael Vecchione, a research zoologist at the Smithsonian’s National Museum of Natural History.
 
Vecchione is a co-author of a new paper with H.J.T. Hoving of the Monterey Bay Aquarium, on this behavior in The Biological Bulletin.
 
“We knew the terminal organ was located in the mantle of the male but we didn’t know that it projected through the funnel. The male was upside down, that also was surprising,” he said.
 
Recording the video of the act - at a depth of 1,400 meters in the northern Gulf of Mexico - was the ROV Little Hercules on April 13 last year.
 
Detailed observation

The video showed the male upside down, and backwards on top of the female, his terminal organ extending from his funnel, presumably releasing spermatophores.
 
It was the first detailed observation of the mating behavior of a deep-sea squid species, and addressed questions stemming from the study of the sexual organs of these creatures in museum specimens.
 
An earlier video of the same species recorded in 2006 also contributed to the findings.
 
Squid 'penis' is actually an arm
 
SmithsonianScience.org said many squid species use a modified arm - a hectocotylus - to transfer spermatophores to the female.
 
Others such as the P. adami squid in the video and giant squid have no hectocotylus but use the penis or terminal organ of the male reproductive tract.
 
“Penis is probably a less appropriate name for the organ because it is not homologous with a mammalian penis but it is used in basically the same way,” Vecchione said.
 
Burrowing into the female

A male squid’s organ emits spermatophores, which contain millions of sperm that turn inside out and attach sperm packages to the female’s body.
 
The sperm then apparently burrow into the female’s tissue.
 
Vecchione also noted one thing that surprised many was how long the mating process lasted.
 
“In this species the spermatophores inject sperm deep into the muscle of the female’s dorsal mantle. Because of this we guessed their mating was a really quick process in which the male darts in, shoots the female and then leaves. The video reveals it is a long process where the male is basically hanging on motionless for a long time. They were in that position when we first saw them in the video and they were still in that position when they swam away,” he said.
 
He also said a big mystery of squid life history was how sperm implanted in the female’s muscle tissue and skin move to a location in the female’s body where they can fertilize her eggs.
 
In P. adami, the sperm are implanted just outside and above where the eggs come out of the female’s oviduct.
 
“Probably what happens is that the sperm actually burrow through the rest of the dorsal muscle and into the female’s interior mantle to fertilize the eggs as they are coming out. But that’s a guess. We really don’t know,” he said. — TJD, GMA News



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