Tag Archives: mantis

How some male mantises avoid getting their heads chopped off after sex

A female mantis with an abdominal wound from wrestling with a horny male. Credit: Biology Letters, Nathan Burke.

Mantises are famous in the animal kingdom for their extreme sexual cannibalism. If given the chance, females will often bite off the heads and eat other body parts of the male that they mate with. In the process, they acquire important nutrients that are incorporated into the eggs, thereby improving the odds that a male passes his genes — so not a totally unfair bargain. But some crafty males want to have their cake and eat it too.

In a new study, researchers documented how male springbok mantises (Miomantis caffra) manage to mate and escape cannibalism, finding that the insects dramatically improve their odds of surviving mating if they violently wrestle the females. Pinning down the female helps the male mate and come out unscathed, serving as both a mating and survival tactic.

Although female mantises are famous for exhibiting cannibalism of their mates, research suggests that females eat their mate just 13% to 28% of the time. Springbok mantises, however, fit the stereotype of a merciless fatal sexual encounter, killing their male spouses 60% of the time.

It then makes sense that the male springboks have had to evolve some sort of defence mechanism. Not having sex is, after all, not a solution either.

In order to learn how some males escape the particularly aggressive cannibalistic tendencies of the females, biologists at the University of Auckland in New Zealand organized gladiator-like showdowns between 52 male-female pairs.

Healed abdominal wound in a female. Credit: Biology Letters.

Within 12 hours of being placed in the same enclosure in the lab, 56% of the males initiated contact with the female. They did so very aggressively, leaping onto the females while rapidly fluttering their wings. About 90% of these contacts turned into violent albeit short-lived struggles. Lasting only 12.7 seconds on average, these struggles often resulted in the male inflicting a serious but non-fatal wound to the abdomen of the female using his serrated raptorial forelegs.

When the male managed to pin the female down, he stood a 78% change of escaping unscathed. The females won more than one-third of these wrestling matches, pinning down and cannibalizing the males in 35% of the cases.

However, not all winning showdowns resulted in a mating opportunity for the males. Coupling occurred only two-thirds of the time.

“When females win the struggle, they always cannibalize males. However, when males grasp females first, they dramatically increase the chance of mating. We also find striking evidence that, on some occasions, males wound females with their fore-tibial claws during struggles, resulting in haemolymph loss and scar tissue formation,” the researchers wrote in the journal Biology Letters.

The researchers believe that the reason why males evolved such harmful and aggressive behaviors is due to the even greater threat posed by the females. The males simply have to do whatever they can in order to both survive and replicate, and this dual strategy can lead to some pretty peculiar outcomes, such as two parents who are willing to kill each other during mating.

Panda Solar Plant.

Chinese pandas will slash over 2.74 tons of CO2 emissions in the next 25 yeas — because they’re solar plants

Not yet sold on the idea of solar plants? Even if it was as solar plant… shaped like a panda? Thought so.

Panda Solar Plant.

Image via ledpv.com

It’s an undeniably creative advertising stunt, and it’s actually something which will definitely make Shanxi province of China stand out. The brainchild of Panda Green Energy (formerly known as United Photovoltaics) and the United Nations Development Program, the so-called Panda Power Plant has been under construction since November 2016. To get the panda shapes just right, the group used thin film solar cells for the white and gray face and belly and monocrystalline silicon solar cells to ink in the black areas.

Progress on the plant is going quite well. The first phase/Panda of the project has been completed and is currently churning out some 50 MW of clean, adorable energy into the Chinese grid. Once fully completed, the pandas will have an aggregate capacity of 100 MW and are projected to provide 3.2 billion kWh of electricity over the next 25 years — equivalent to 1.056 million tons of coal or 2.74 million tons of carbon dioxide emissions.

But it’s not merely about energy. The Panda project also aims to invest in the future of the communities it serves, and as such, will come equipped with an activity center to educate local schoolchildren about solar energy and its benefits. For a country left struggling with immense climate issues following what may be the biggest industrialization effort ever seen, projects such as the Panda Power Plant are key to a healthier, cleaner future.

Panda Solar Plants.

A way cuter future, to boot!
Image credits Panda Green Energy Group Limited.

Panda Green Energy revealed that more solar farms are planned over the next 5 years as part of their Panda 100 program. These will be built along the Belt and Roads areas that are part of President Xi Jinping’s economic development strategy.

And yes; they will all be pandas.

Mantis shrimps teach humans how to make a new type of optical material

Some time ago we wrote about the mantis shrimp’s uncanny form of communication: polarized light. Research focusing in on these tiny animals’ chatter will allow us to create a whole new type of polarizer — an optical device widely employed in modern cameras, DVD players, even sunglasses.

Mantis shrimp are probably best known for the dazzling colors that adorn their shells. The second thing they’re best known for is their tendency to violently murder anything they come into contact with. Using two frontal appendages that can move as fast as a bullet, the shrimp hunts for crabs, oysters, octopi, anything really, blasting them apart with an insanely powerful 1,5 kilo Newtons of force (337.21 lbs of force.)

Look at him. He just knows he’s the baddest shrimp in this pond.
Image via wikipedia

But why? And how did they come by their weapons? What is the mantis shrimp’s secret? Well nobody knows, because they communicate using a process so secretive most other species don’t even realize it’s happening.

The shrimp rely on light polarization to keep their conversations private. They have evolved reflectors that allow them to control the polarization of their visual signals, a property of light that most other species aren’t able to pick up on.

In an effort to crack their code, researchers from the Ecology of Vision Group (based in the University of Bristol’s School of Biological Sciences) have studied the shrimps and discovered they employ a polarizing structure radically different from anything that humans have ever seen or developed.

The team’s analysis, coupled with computer modelling revealed that the mantis shrimp’s polarizers manipulate light across it’s structure rather than through its depth — as our polarizers do. This mechanism allows the animal to have small, microscopically thin and dynamic optical structures that still produce big, bright and colourful polarized signals.

“When it comes to developing a new way to make polarizers, nature has come up with optical solutions we haven’t yet thought of,” said Dr Nicholas Roberts from the School of Biological Sciences.

“Industries working on optical technologies will be interested in this new solution mantis shrimp have found to create a polarizer as new ways for humans to use and control light are developed.”

The full paper, titled ‘A shape-anisotropic reflective polarizer in a stomatopod crustacean’ is available online here.

Deceptive Female Mantises Eat Males Even Without Having Sex

It has been known for quite some time that male praying mantises can get their heads ripped off while copulating with females. But a new study has shown that deceptive females can trick the males and eat them even without copulation; basically, they lure them in pretending to be full of eggs and eat them when they’re hungry.

“This is the first evidence in support of the Femme Fatale hypothesis, which posits that female mantids in poor condition might dishonestly entice males in order to eat them rather than mate with them,” said lead research Dr Kate Barry, of Macquarie University’s Department of Biological Sciences.

The study initially found that males are more attracted to starving females, despite the chance of being eaten during copulation.

mantis

Image via 5oclockam.

 

“We presume this attraction is due to an increase in the quality or quantity of pheromone emissions, which makes sense because very hungry females gain both survival and reproductive benefits from attracting and consuming a male.

They then observed that some females (which are much larger than the males) eat the males even without reproduction. They set up large large field enclosures on the Macquarie University campus to examine the potential for sexual deception in females.

They found that healthy, well fed females sometimes lure in males with no intention of reproducing, just to eat them. However, hungry females are much more likely to do this. To figure this out, researchers assigned 24 female to one of four feeding regimes: good, medium, poor, or very poor, for six weeks. The cages were covered with two layers of mesh so that you couldn’t see inside of them, but chemical signals could still be released. 78 virgin males were then released and out of them, 55 were found on female cages. The number of males found on specific cages was used as an indicator of female attractiveness.

This is the first time that females exploiting males has  been reported in nature… and it’s also the most extreme example of sexual manipulation ever found.

“There are many examples in the animal kingdom of males exploiting females to secure paternity, however in this instance, female praying mantids have turned the tables.”