Tag Archives: praying 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.

3d vision praying mantis

Scientists outfit praying mantises with tiny 3D glasses, find new type of stereo vision

3d vision praying mantis

Credit: MIKE URWIN.

Each of our two eyes sees the world slightly differently but luckily our brain has evolved a way to combine the two pictures into a single image. The difference in details between the two is what allows us to estimate how far away things are or to estimate depth, which is why it’s also called 3D vision. Besides humans, there are many other animals which use stereo vision, such as cats, mules, toads, and the praying mantis. The latter is actually the only insect that has stereo vision and, what’s more, the researchers at Newcastle University discovered that it is a new kind of stereo vision that thus far appears to be unique to the mantis.

To investigate how the praying mantis 3D vision works and differs from our own, the British researchers devised special, tiny 3D glasses that were temporarily glued to the heads of mantises with beeswax. They then introduced the insect into — where else — a 3D cinema.

Basically, the researchers played a movie of tasty prey hovering right in front of the mantis — an illusion so realistic that the mantises tried to catch it with their famous claws. The movies shown to the insects were both simple movies of bugs as well as complex dot-patterns typically used by doctors to investigate human 3D vision.

We, as humans, are very good at seeing in 3D, as far as still images are concerned, because we match up the details of the picture produced by each of our two eyes. Mantises only attack moving prey, and so their 3D vision works fundamentally different. After various trial runs, the Newcastle researchers found that the bugs don’t bother at all about the details of a picture and instead look for the places where the picture is changing, such as moving prey over a background.  

The mantis stereo vision is very robust because even if the insect’s two eyes produced completely different images, they would still be able to identify the places where things are changing. Indeed, in tests, the mantises could do this in cases where humans couldn’t.

“This is a completely new form of 3D vision as it is based on change over time instead of static images,” said behavioral ecologist Dr. Vivek Nityananda at Newcastle University.  “In mantises, it is probably designed to answer the question ‘is there prey at the right distance for me to catch?’”

A Newcastle University engineering student developed an electronic mantis arm which mimics the distinct striking action of the insect. Credit: Newcastle University.

A Newcastle University engineering student developed an electronic mantis arm which mimics the distinct striking action of the insect. Credit: Newcastle University.

The most immediate applications involve robots. Today, robots that use stereo vision to navigate their surroundings do so analogously to humans. For all intents and purposes, this works out nicely but the main drawback is that our form of stereo vision requires a lot of computer processing.

If the next generation of robots uses mantis stereo vision algorithms —  based on change over time instead of static images — they will use far less processing power. This means you can have autonomous robots that are far smaller and last much longer on a battery than ever before.  

Scientific reference: A novel form of stereo vision in the praying mantis. Vivek Nityananda, Ghaith Tarawneh, Sid Henriksen, Diana Umeton, Adam Simmons, Jenny C. A. Read. Current Biology. Doi: 10.1016/j.cub.2018.01.012/.

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.

Predatory cockroach found in 100 million year old amber

Geologists have found a praying-mantis-like cockroach that lived at the side by side with the dinosaurs, 100 million years ago, during the mid Cretaceous. The insect was preserved in amber.

Peter Vršanský from the Geological Institute in Bratislava, Slovakia, and Günter Bechly from the State Museum of Natural History in Stuttgart found the insect at a mine in Noije Bum, Myanmar. The specimen was one of many found in the area, and is related to today’s praying mantises. Out of all the predatory cockroach lineages that evolved in the Cretaceous, only praying mantises survive today.

According to the two researchers, its long neck, which allows the head to rotate freely, and unusually long legs area a good indication that it actively hunted prey.

“The new species exemplifies the reverse trend to that observed in the mantodeans, namely an elongation of extremities, including palps. This elongation especially applies to the elongation of tibia. In addition to the pursuit predatory lifestyle, it can be inferred that these insect were autochthonous inhabitants of the Cretaceous Araucaria amber forest in Myanmar. This inference is mainly based on the fact that four additional specimens of this new taxon (with one early immature specimen) are known to us from traders of Myanmar amber inclusions,” the study reads.

The Cretaceous was a period with a relatively warm climate, resulting in high sea levels. It is the period when many new groups of mammals and birds, as well as flowering plants, appeared.

Journal reference: Geologica Carpathica, DOI: 10.1515/geoca-2015-0015

praying mantis

How the praying mantises make their amazing leaps

Praying mantises are peculiar creatures, by human standards. The insect often stands in a pose that looks like it is praying, but make no mistake – it’s a formidable killer and an unforgiving lover. The unholy mantis uses its spiky front legs with great accuracy to ledge unto prey, but also to hold onto its male lover after mating to chop of his head. Ouch! A less known aspect of praying mantises is their agility. The insects make extremely calculated leaps and controlled landings, all in the blink of an aye. Now, a team from University of Cambridge and University of Bristol, UK, have found out how they manage their acrobatic feats. In short, it’s a complex interplay between the counter-rotation of three body parts to exchange momentum. This orients the insect towards its target with great precision.

A deadly dance

praying mantis

Image: Wikicommons

Praying mantises make a complete leap in a tenth of a second. To study them, the team employed high speed video imagery of 58 juvenile mantises as the insects leapt across a distance of about one to two mantis body lengths, unto a black rod. Juveniles were preferred because these don’t have any wings yet, so they’re only option is to jump.

By carefully analyzing each video, the researchers noticed a recurring pattern. First, the insects swayed their heads back and forth like a cobra,  eyeing up the vertical target to estimate distance. Then, like a feline preparing to pounce, the mantis wiggled its body back and forth to adjust its center of mass. This ensures the middle and hind legs act just sufficiently away from the centre of mass to impart a spin on the body as it leaves the platform. Once ready, the insect leaps off, but spins in mid-air at the same time in a controlled manner. It rotates roughly 2.5 times a second.

“This is akin to asking an ice skater who is rotating at the same speed as these mantises to stop suddenly and accurately face a specific direction,” Malcolm Burrows, an entomologist at the University of Cambridge, says in a release.

It’s not an uniform spin, though. Instead, their abdomen, front legs and hind legs coordinate in a discontinuous fashion, like a wave. In all this time, the rotating members exchange momentum between them, keeping the spin of the whole body at the correct rate to successfully reach and land on the target. Only in the last 10 milliseconds of the jump did the insects stop rotating, according to the paper published in Current Biology.

The researchers came to know this by two means: one theoretical, the other experimental. First, they made a mathematical model. When they forced one of the body parts from rotating, the simulation showed the virtual insect rotated twice as fast and missed its target. To verify this, they glued the abdomen of one of the juveniles so it couldn’t curl anymore. Once it leaped, it took off with less spin and landed on the target head first. Check out the video above.

There are a lot of insects which are formidable jumpers. Flees, for instance, can jump 100 times their height with tremendous acceleration. However, it jumps hectic and makes an uncontrolled landing. Of course, if the flee can’t predict where it’ll land, so can’t predators. This makes it a great escape mechanism. The praying mantis is a lot different and because of this, it’s rather unique as far as insects go. Next, the team plans on picking its brain to find out what are the neural mechanism behinds its fascinating acrobatics. Research like this might aid robotics experts build agile robots, like Boston Robotics’ sand flea robot.