Moving thousands of times faster than the blink of an eye, the springy jaws of an ant with trap jaws catch the insect’s prey by surprise, and at the same time, if the ants point to the ground, they can throw the ant into the air. Now, scientists have uncovered how the ant’s jaws close at blistering speeds without breaking apart from the force.
In a new study published Thursday, July 21, Journal of Experimental Biology (opens in new tab)A team of biologists and engineers studied a species of trap-jaw ant called Odontomachus brunneusIt is native to parts of the USA, Central America, and the West Indies. To build up the force for their lightning-quick bite, the ants first spread their jaws apart so they form a 180-degree angle and “cock” them against the pegs inside their heads. Enormous muscles attached to each jaw by a tendon-like cord pull the jaws in place and then flex to create a reservoir of elastic energy; The team found that this bending was so extreme that it twisted the sides of the ant’s head, causing the ants to bend inward. When the ant strikes, their jaws open and this stored energy is suddenly released and their jaws crash into each other.
The researchers studied this spring mechanism in fine detail, but the project’s engineers were confused about how the system could work without creating too much friction. Friction not only slows down the jaws, but also causes destructive wear and tear at the pivot point of each jaw. Using mathematical modeling, they finally found an answer to how trap-jaw ants avoid this problem.
“This is the part engineers are incredibly excited about,” said Sheila Patek, Hehmeyer Professor of Biology at Duke University, in part because the discovery could pave the way for the construction of tiny robots whose parts can rotate with unmatched speed and precision. Durham, North Carolina, and the study’s senior author told Live Science.
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A nearly frictionless, spring-loaded system
To examine their incredible jaws brunneusPatek and his colleagues collected ants from a colony of bushes near Lake Placid, Florida. Back in the lab, the team dissected some of the ants and made detailed measurements and micro-CT scans body parts, especially the jaws, muscles, and exoskeleton of the head. They then fitted these measurements into mathematical models of the ants’ movements.
In addition, the team placed some ants in front of a high-speed camera that shoots at 300,000 frames per second. (For comparison, video is typically shot at 24 to 30 frames per second.) These videos revealed that as the ants prepared to attack, the exoskeleton covering their heads was significantly compressed, shortening by about 3% and growing lengthwise. about 6% thinner in the middle. This compression takes place over a few seconds and is slow compared to the ant’s quick bite, Patek said.
After being released from their latches, the ants’ jaws curved perfectly, reaching their top speed around the 65-degree mark before starting to slow down. The ants’ jaw tips traveled the fastest in the air at around 120 mph (195 km/h).
The team determined that this ultra-fast motion occurs smoothly and precisely thanks to several forces acting on the jaws simultaneously.
First, when the ant’s head returned to its normal shape, it threw the tips of each jaw into space. Meanwhile, the large muscles inside the ant’s head relaxed and stopped stretching the tendon-like cords to which they were attached. As each cord returned to its normal length—think of a stretched rubber band suddenly released—it was pulled from the end of the jaw that sat inside the ant’s head. It is this simultaneous push and pull that causes the ant’s jaws to fly toward each other.
Related: These worker ants drag their queens to their far away single homes to mate.
A similar principle applies when you turn a bottle on a flat surface; The twisting motion required to turn the bottle involves pushing one end of the bottle forward while pulling the other end back. Similarly, when ballerinas perform pirouettes with the support of a partner, the partner will push one hip forward and pull the other back to activate their row. However, the best analogy for the trap-jaw ant’s jaw movement might be stick juggling, a circus art in which players use two sticks to spin a stick through the air.
The rod encounters very little friction as it spins through the air, and the study authors think, based on their mathematical model, that the jaws of a trap-jaw ant are similarly free. At first, the researchers thought that each jaw could rotate around a pin joint, similar to a door on a hinge, but determined that such a structure would offer too much resistance. Instead, they found that the jaws revolved around a much less rigid joint structure in the ant’s head that required little reinforcement.
“The double spring mechanism greatly reduces reaction forces and friction in this joint, so the joint doesn’t need as much reinforcement to hold the lower jaw in place,” says first author Gregory Sutton, a Royal Society University Research Fellow. The University of Lincoln in England told Live Science in an email. The authors concluded that the lack of friction in this system could explain how trap-jaw ants can attack repeatedly without ever harming themselves.
The authors state that all trap-jaw ants odontomacus The genus uses the same spring-loaded mechanism to bite, but trap-jaw ants in other species may use a slightly different strategy, Patek said. However, Patek suspects that the mechanism they discovered could also be used by other arthropods, meaning insects, spiders and crustaceans.
For example, mantis shrimpFamous for throwing punches at 80 km/h, it probably bends their exoskeleton and uses super-flexible tendons to build power for each strike – but no such mechanism has yet been identified in shrimp.
“We’re starting to realize that this will be the rule of thumb for these superfast arthropods,” Patek said. Said.
Originally published on Live Science.
