Female dumpling squids just can't catch a break -- mating is awful for them. Insemination can induce physical trauma, take a long time, and sometimes the male will just keep boning the female while predators are around. Poor, tiny little boning dumpling squids.
Image: Mark Norman / Museum Victoria/Wikimedia Commons
Given the apparent horrors of sex, some scientists from Australia and the United States wanted to know just how bad its effects were on the female dumpling squids. Their conclusion? Bad. It seems to literally kill them.
"By comparing the adult lifespan of virgin, once-mated and twice-mated female dumpling squid," write the authors in their paper published in the Journal of Evolutionary Biology, "we investigated the hypotheses that once-mated females will experience a longevity cost and that twice-mated females will experience an additional reduction in longevity."
The researchers started by acquiring juvenile female and adult male squiddies during a few nighttime scuba dives in shallow waters off the coast of Victoria, Australia, and raised the males and females separately in glass tanks. Once the females started reaching sexual maturity, it was sex time.
The researchers split the female squids into one of three groups of around 10 each: Virgin, one screw or two screws. They put each lady squid into individual tanks, then put a sexually mature male in. The researchers had some difficulties getting the lil' dumpies to bone, which they fixed by either "gently disturbing" the females (as if traumatic mating isn't disturbing enough) or by putting a different male into the tank. After sex, the scientists continued to support the squids until they died, which took a few months. A few of the virgins had already boned in the wild before reaching sexual maturity and stored the sperm, so the researchers didn't include them in the final analysis.
That analysis presented some pretty sad news: Virgins lived 15 days longer than the females who mated once, and the ones who mated once lived eight days longer than the ones who mated twice.
A few things could have caused the lifespan reduction, like using up more energy, diseases passed along from the wild male squids, or injuries from the boning. Though the researchers found other things were associated with longevity too, like the water temperature.
There are plenty of caveats, of course -- this was a single study done on a fairly small sample of lab-reared squids. But the signs do seem to point towards screwing more meaning dying faster in these squids.
Ultimately, this study highlights some of the tradeoffs of evolution -- some animals might live longer, bone less and lay fewer eggs. Some animals might bone more, lay more eggs, and die sooner. There are always awful tradeoffs in the game of evolution.
But all of this really is to say that dang, it sucks to be a squid.