Photograph courtesy MBARI
Published September 20, 2011
When it comes to mating, some male squid aren't very picky: They copulate just as often with other males as with females, a new study says.
That's because would-be suitors of the hand-size species Octopoteuthis deletron, which live in the murky depths of the eastern Pacific Ocean, can't easily tell the males from the females, the research shows.
"They can see each other, but they are not able very well to distinguish between the sexes at the distance at which they decide, 'I'm going to mate' or 'I'm not going to mate,'" said study leader Hendrik Hoving, of the Monterey Bay Aquarium Research Institute in California.
So "males mate with basically any member of the same species. ... They just take a chance."
It's also hard to tell he from she: A female squid's defining feature is a patch of wrinkled skin. (See squid pictures.)
The result is a strategy that the study authors call "a shot in the dark"—it's just not worth it to males to make sure their partner is the right gender.
Same-Sex Mating Rare in Nature
For the study, Hoving and colleagues recorded squid via robotic submarines in the dark, 1,300 to 2,600 feet (400 to 800 meters) underwater. The scientists observed more than a hundred male and female squid, and found that just as many male squids as female squid bore sperm packets on their bodies—showing that males slap a sperm packet on just about anything with eight arms.
When he finds a suitable partner, the male uses his large penis to transfer multiple sperm packets to the male or female. These break open into smaller sperm sacs that attach to his partner's mantle, fins, and arms.
But the "love affair" ends there: The squid, which lead a solitary existence, die shortly after mating.
Nathan Bailey, of the U.K.'s University of St. Andrews, said the study team "makes a pretty good case" for their claims about the male squid's lack of choosiness.
Very few species show such high levels of what biologists call same-sex sexual behavior, Bailey, who wasn't involved in the research, said by email. "Some primates or dolphins do, but this study puts O. deletron on the higher end of the scale."
Hoving acknowledged that his research results can become fodder for jokes.
"But I don't really care," he said. "I'm interested in deep-sea animals and how they're capable of living in that environment, and one of the challenges is finding the opposite sex."
The study appears in this week's issue of the journal Biology Letters.
Bug-eyed frog and "Chewbacca bat" among 1,200 newly discovered species in Africa.
Armchair astronomers can see a live web broadcast of Saturn this week and pose for a snapshot of Earth from space next month.
New York City amps up food recycling, while San Francisco shows the way.
Celebrating 125 Years
Connect With Nat Geo
Special Ad Section
Shop National Geographic
Great Energy Challenge Blog
- Study Says: Hey, You, Get Onto the Cloud (It Saves Energy)
- Who Will Swelter This Summer? The Pressures on the Nation’s Power Grid
- Tar Sands Tour: Boomtown, Scarecrows, and Spin; “We Have Met the Enemy, and He is Us”
- Climate Change: China, U.S. Bring Toy Fire Truck to Seven-Alarm Fire
- Student Infographic Contest Paints Bright Picture of Youth Concern on Energy and Climate