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Moving at speeds thousands of times faster than the blink of an eye, the trap ant’s spring-loaded jaws catch the insect’s prey by surprise, and can also throw the ant into the air if it aims its rodents at the ground. Now scientists have figured out how an ant’s jaws can close at lightning speed without collapsing.
In a new study published on Thursday (July 21) in Journal of Experimental Biology (will open in a new tab)a group of biologists and engineers studied a type of ant trap called Odontomachus brunneus, native to parts of the US, Central America and the West Indies. To build up strength for their lightning-fast bites, ants first open their jaws to form a 180-degree angle and “cock” them against the latches inside their heads. Enormous muscles, attached to each jaw by a tendon-like cord, pull the jaws into place and then flex to create a store of elastic energy; this flexion is so strong that it deforms the sides of the ant’s head, causing them to bend inward, the team found. When an ant strikes, its jaws open and the stored energy is immediately released, causing the jaws to collide with each other.
The researchers studied this spring-loaded mechanism in great detail, but the project’s engineers puzzled over how the system could work without creating too much friction. Friction would not only slow down the jaws, but would also cause devastating wear at the pivot point of each jaw. Using mathematical modeling, they eventually figured out how ant traps avoid this problem.
“This is the part that engineers are incredibly excited about,” in part because this discovery could pave the way for the construction of tiny robots whose parts can spin at unprecedented speed and precision, Sheila Patek, Hemeyer Professor of Biology at Duke University in Durham, North Carolina, and senior author of the study, told Live Science.
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Virtually silent spring-loaded system
To explore incredible jaws O. brunneus, Patek and her colleagues collected ants from a colony found in bushes near Lake Placid, Florida. Back at the lab, the team dissected some of the ants and performed detailed measurements and microanalysis.CT parts of their body, especially the jaws, muscles and external skeleton of the head. They later incorporated these measurements into their mathematical models of ant movements.
In addition, the team placed several ants in front of a high-speed camera that captured footage at a whopping 300,000 frames per second. (Video is typically shot at 24 to 30 frames per second, for comparison.) These videos showed that as the ants prepared to strike, the exoskeleton covering their heads underwent significant contraction, shortening by about 3% in length, and growth. about 6% thinner in the middle. According to Patek, this contraction took place within seconds, which seems slow compared to the quick sting of an ant.
Once released from the latches, the jaws of the ants moved in a perfect arc, reaching a maximum speed around the 65-degree mark before starting to slow down. The fastest ant jaw tips moved through the air at about 120 miles per hour (195 km/h).
The team determined that this ultra-fast movement unfolded smoothly and precisely thanks to multiple forces acting on the jaw at the same time.
First, as the ant’s head returned to its normal shape, it catapulted the tip of each jaw into space. Meanwhile, the large muscles inside the ant’s head relaxed and stopped stretching the tendons to which they were attached. As each cord returned to its normal length – imagine a stretched rubber band suddenly released – he tugged at the end of the jaw that is inside the ant’s head. This simultaneous push and pull caused the ant’s jaws to fly towards each other.
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A similar principle applies when you spin the bottle on a flat surface; the rotational motion required to rotate the bottle involves pushing one end of the bottle forward and pulling the other end back. Similarly, when ballerinas perform pirouettes with the support of a partner, the partner pushes one of her hips forward and pulls the other back to set her in motion. However, a better analogy for the movement of the mandible of an ant trap might be stick juggling, a circus art in which performers use two sticks to spin a wand in the air.
The baton encounters little friction as it flips in the air, and based on their mathematical models, the study authors believe that the mandibles of the trap ant are also unrestricted. At first, the researchers thought that each jaw could rotate around the pin connection, like a hinged door, but they determined that such a design would create too much resistance. Instead, they found that the jaws rotate around a much less rigid articular structure, which requires a bit of reinforcement in the ant’s head.
“The dual spring mechanism dramatically reduces reaction forces and friction at this joint so that the joint does not need much reinforcement to keep the mandible in place,” said study co-author Gregory Sutton, a research fellow at the Royal Society University. Lincoln University in England, Live Science told Live Science in an email. The authors concluded that the lack of friction in this system could explain how trapping ants can strike again and again without ever getting hurt.
The authors believe that all ant-traps in Odontomach Members of this genus use the same spring-loaded mechanism to bite, Patek says, but trap ants in other genera may use a slightly different strategy. At the same time, Patek suspects that the mechanism they discovered may well be used by other arthropods, that is, insects, spiders and crustaceans.
For example, mantis shrimpknown for hitting at 80 km/h likely deform their exoskeleton and use superelastic tendons to build power with each hit, though no such mechanism has yet been found in shrimp.
“We are beginning to realize that this will be the rule of thumb for these ultra-fast arthropods,” Patek said.
Originally published on Live Science.
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