Oliver Koemmerling via Wikimedia Commons // CC BY-SA 3.0
Oliver Koemmerling via Wikimedia Commons // CC BY-SA 3.0

Why Lady Mantises Eat Their Mates

Oliver Koemmerling via Wikimedia Commons // CC BY-SA 3.0
Oliver Koemmerling via Wikimedia Commons // CC BY-SA 3.0

If one out of every four of your sexually active friends got eaten, you’d probably start to consider a sex-free lifestyle. Unless, of course, you’re a male praying mantis, in which case you’d go for it anyway. The male bugs’ apparent eagerness to go to their mid-coital deaths has puzzled scientists for some time. One 2016 study may have an explanation: being eaten could actually increase a male’s chance of passing on his genes. The study was published in the Proceedings of the Royal Society B. 

Mantis sex is … intense. About 25 percent of encounters include sexual cannibalism, in which the female mantis literally bites her mate’s head off. But a little thing like that is not going to deter the missing male, who will go on humping like nothing has happened, even as the female continues to nibble him into nothingness. This can take hours.

True romance: a female mantis eating her mate's genitals. Image Credit: Oliver Koemmerling via Wikimedia Commons // CC BY-SA 3.0

He is, in essence, offering his body as a present. This sexual gift-giving is not uncommon in insects—the males in one cricket species even make gummy snacks for their mates—but most of these gifts are not also the gift-givers. From an evolutionary perspective, it makes a lot of sense: females can share the nutrient boost with their fertilized eggs, which gives the kids a better chance of surviving. Was that what was going on in mantises? To find out, researchers set up a little mantis love hotel. 

The first step was to provide a romantic meal. The scientists treated small crickets with radioactive amino acids, then fed those crickets to a group of male mantises. Then each male was paired with a female and allowed to mate. Half of the mantis pairs were separated before the female could get her chow on. The other half were left alone to play out their grisly romance. 

In eating her partner, a female also ate the contents of his stomach. So by tracking those radioactive cricket particles, the scientists were able to determine how females’ bodies were using their most recent meal.

As it turns out, even uneaten males were giving their partners a little something. On average, male mantises who survived passed on 25 percent of their radioactive amino acids via their ejaculate. But, as expected, a dead dad could do even more for his kids; gobbled-up males gave their mates a full 90 percent of their nutritious amino acids, and their mates passed the goodness on to their young. 

Being devoured also improved a male’s genetic success by increasing the number of eggs laid by his partner. Females in the coitus interruptus pairings—those who didn’t get to eat—laid about 37 eggs apiece. Those who finished their dinner dates, on the other hand, produced around 88. 

We’ve still got plenty to learn about these beautiful creatures and their slightly terrifying sex lives. But these findings do, at least, make sex-positive male mantises seem slightly less foolhardy. 

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iStock
Good News, Dog Parents: You Can Teach Puppies as Well as Their Canine Moms Can
iStock
iStock

If you’ve ever adopted a puppy, you probably know how frustrating it can be to teach your new family member the basic tenets of common decency, like not to pee on the carpet or tear up a whole roll of toilet paper.

In other areas, though, pups are rather impressive learners, capable of mimicking some human behaviors. In fact, for some tasks, they learn just as effectively from watching people as they do from watching other dogs, including their own mothers, a new study in Nature revealed.

Researchers from Hungary and the UK took 48 young puppies of various breeds and studied the conditions under which they can be taught to open a puzzle box containing food. The experiment revealed that the puppies were able to learn how to open the box regardless of whether the task was first demonstrated by a person, their mother, or an unfamiliar dog. In other words, not only are puppies capable of social learning, but they're able to learn tasks from humans they don't know—in this case, the experimenter.

However, researchers were surprised to learn that the puppies were more likely to learn how to open the box by watching an unfamiliar dog than by watching their own mothers. That may be because puppies spend more time looking at—and thus, learning from—an unfamiliar dog that intrigues them. This differs from other species such as kittens, which “learn to press a lever for food more rapidly from their mother than from an unfamiliar adult,” the study notes.

In addition, the puppies were able to perform the task again after a one-hour break, indicating that they had retained some memory of the learning experience.

The ability of dogs to learn from humans has been recorded in previous research. A 2015 study revealed that dogs learn better by demonstration (or the “do as I do” method) than training techniques that involve a system of punishments and rewards. The "do as I do" approach probably isn't the most practical method of teaching your pup to do its business outside, but if you already have an adult dog at home, your new puppy can follow the older dog's lead and learn by example.

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Michael Hutchinson
Spiders Can Fly Through the Air Using the Earth's Electric Field
A spider exhibiting ballooning behavior.
A spider exhibiting ballooning behavior.
Michael Hutchinson

Every so often, otherwise Earth-bound spiders take to the air. Ballooning spiders can travel hundreds of miles through the air (and, horrifyingly, rain down on unsuspecting towns). The common explanation for this phenomenon is that the spiders surf the wind on strands of silk, but there may be other forces at work, according to a new study spotted by The Atlantic.

In the research, published in Current Biology, University of Bristol scientists argue that Earth's atmospheric electricity allows spiders to become airborne even on windless days. To test their hypothesis, the researchers exposed spiders in the lab to electric fields similar to those naturally found in the atmosphere.

When the electric field was turned on, the spiders began to exhibit behavior associated with ballooning—they "tiptoed" on the ends of their legs, raised their abdomens, and released silk. Spiders only exhibit this behavior when ballooning. And when they did become airborne, the spiders’ altitude could be controlled by turning the electric field on and off. When the electric field was on, they rose through the air, but when it was off, they drifted downward.

This provides a potential explanation for why spiders take to the skies on certain days but not others, and how they can fly in calm, windless weather— something scientists have puzzled over since the early 19th century. (Even Darwin was flummoxed, calling it "inexplicable," The Atlantic notes.) However, the researchers note that these electric fields might not be totally necessary for ballooning—wind alone might work perfectly fine on some days, too. But understanding more about when and how spiders become airborne could help us predict when there will be large masses of arachnids flying through the skies (and hide).

[h/t The Atlantic]

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