Threat of Being Eaten Doesn’t Deter Dumpling Squid From Sex

Love can make you crazy. But while taking risks for romance usually tops out at embarrassment or heartbreak for smitten humans, love—or, more accurately, mating—can be lethal in the animal world. In the rush to reproduce, animals can expose themselves to mortal danger, either because their strength gets sapped or because they are increasing their chances of being spotted by a predator and getting eaten mid-act.

There’s no set rule for how animals approach the trade-off between reproduction and safety. For the dumpling squid—an adorable, cartoonish species of cephalopod that lives in shallow waters off Australia—it turns out that the threat of imminent death does little to deter couples from mixing gametes.

Dumpling squid aren’t particularly well studied, but scientists do know a bit about their basic mating behavior. The male grabs and physically restrains the female, then inserts and enlarges a special sperm-transfer organ called the hectocotylus into the female’s sperm storage organ, the spermatheca. At the end of copulation, the male jerks his hectocotylus out of the female, effectively terminating the tryst. Based on those behavioral observations, researchers hypothesized that dumpling squid males call the shots when it comes to sex.

To see how the squid behave in the face of danger, researchers from the University of Melbourne collected 15 pairs of wild dumpling squid from the waters off Victoria, Australia. They also scooped up 15 of one the squid’s most common natural predators, a type of fish called the sand flathead. They put each squid pair into separate containers, then exposed them to various kinky scenarios, including introducing a predator before the squid began to mate, during mating and an hour after mating. The researchers noted any defensive behaviors, such as blowing out a cloud of ink to mask their presence or jetting away by quickly ejecting water out of the body.

When predator fish were around prior to mating, female dumpling squid—but not males—were more likely to spray ink. This is probably because males had a longer period to acclimate to the tank: Females were added to the tank 15 minutes after males, to ensure that the males noticed the females immediately rather than lose time while they were adjusting to their new environment. That means the males were able to conceal themselves in the sand prior to both the predator and the female’s arrival.

But the sand flathead’s presence didn’t significantly influence how likely the squid were to couple up immediately after the female was introduced to the tank, or how long the two went at it. And after mating actually began, both males and females tended to ignore the threat, the team reports today in PLOS ONE. The squid did not spray ink or jet away during copulation. For females, the lack of defense might be because of how tightly they were being squeezed by the male; even if they wanted to get away, they probably couldn’t.

Finally, both male and female squid ignored the predator when they finished the act—although this might be because the squid were too worn out. According to previous research conducted by the same University of Melbourne group, dumpling squid engage in love acts that last up to three hours. After those exertions conclude, both the male and the female squids’ abilities to swim are impaired for up to half an hour.

From an evolutionary standpoint, it seems these squid prioritize reproduction over safety, the researchers conclude. This might be because dumpling squid live short, solitary lives and thus see mating—even in dangerous conditions—as an imperative. 

Here, you can see the study squids' various behaviors in action, from inking to mating:

Squid behaviors: Inking, jetting and copulation

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Rachel Nuwer | | READ MORE

Rachel Nuwer is a freelance science writer based in Brooklyn.