(OCEANS/ANIMAL SCIENCE) Animal reproductive strategies have baffled scientists for generations. From the male bottlenose dolphin to sheep, many species in the animal world exhibit same-sex relationships.

With remote operating vehicles, researchers are documenting the mating habits of male deep sea squid, who not only show same-sex behavior, but mate with males as often as with females. Read more about what scientists think is the reason behind the sea squid’s “swinging” ways. — Global Animal

Squid Histioteuthis is a genus of squid that goes by the common name cock-eyed squid, because in all species the right eye is normal-sized, round, blue and sunken. Photo Credit: L. Madin/Census of Marine Zooplankton
Squid Histioteuthis is a genus of squid that goes by the common name cock-eyed squid, because their right eye is normal-sized, round, blue, and sunken. Photo Credit: L. Madin/Census of Marine Zooplankton

Discovery News, Abbie Thomas

Male deep sea squid are mating as often with other males as with females, according to a new underwater survey off the coast of California.

Hendrik-Jan Hoving and colleagues from the Monterey Bay Aquarium Research Institute report the unusual sexual behavior of Octopoteuthis deletron today in Biology Letters.

Although instances of male-male mating are known from other squid and octopus species, this is the first time it has been found to be as frequent as male-female mating, says Hoving.

The same-sex squid behavior was caught on film by a remotely operated vehicle (ROV) at depths of 400 to 800 meters (1,300 feet to a half mile) in the Monterey Submarine Canyon, a vast underwater valley of similar depth to the Grand Canyon.

Remotely operated vehicles are now able to travel deep enough to record the sea squids reproductive behavior. Photo Credit: Monteray Bay Aquarium Research Institute

The ruby-and-white squid grow to a total length of about 16 inches and have large eyes and long arms tipped with glow-in-the-dark cells. If threatened by a predator, the squid can shed an arm to create a glowing, wriggling decoy. During mating, the male squid uses a modified arm to glue packets of his sperm to the female. These sperm packets release small sperm sacs called spermatangia, which are visible on the female’s body.

The presence of spermatangia on the skin is tangible evidence that a squid has mated.

Of the 19 squid who had mated and whose sex could be determined, the researchers found that nine were males and 10 were females (embedded with between 15 and 150 spermatangia each). This proved that roughly equal numbers of females and males had mated with a male squid.

Hoving says squid can see well in deep water, thanks to their large eyes and light-producing organs in the skin, so it is unlikely that males are mistaking other males for females. So why waste all that sperm on another male?

Hoving suggests that most squid are solitary and because mates are hard to find, a quick sexual encounter gives males the best chance of reproducing, even if it means sometimes accidentally mating with another bloke.

“This behavior further exemplifies the ‘live fast and die young’ life strategy of many cephalopods,” he said.

But Australian expert Mark Norman from Museum Victoria offers an alternative explanation for why the squid accidentally mate with males.

“You may not be sure who’s arm you’re planting sperm packets on, when there are so many arms in a squid’s amorous embrace — 20 limbs total when one male and female meet,” said Norman. “Cannibalism is [also] a high risk in these animals, so a quick deposit of sperm packets, then escape, is probably the main strategy.”

“The most exciting aspect of this discovery is the use of remote vehicles to observe and film these amazing creatures in their natural environment in a non-destructive way,” he said. “We know more about what’s under moon rocks than environments so close to where we live — myriads of these aliens live their strange lives every day and most people have no idea [about them].”

More Discovery News: http://news.discovery.com/animals/squid-same-sex-swingers

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