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What is the leaf cutter ants and dozens of college students have in common? A mouth full of metal teeth.
Tiny arthropods like ants, the spiders and scorpions regularly bite, sting, or pierce hard materials like wood and skin. This is a remarkable achievement, considering that humans find it hard to chew as much as a piece of beef jerky (not to mention a piece of tree bark), even with our powerful jaw muscles.
But new research has shed light on what makes a group of leaf-cutter ants (Atta cephalots) their cutting edge. Powerful use microscopes, scientists have discovered a network of zinc atoms woven into the biological structure of ants’ jaws, giving them the durability of a set of stainless steel knives, the researchers said. This gentle distribution of zinc allows the edge of the ant’s teeth to form a fine point and keeps them sharp for a long time.
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“The little animals that had this material, their muscles are microscopic compared to ours,” Robert Schofield, a biophysicist at the University of Oregon and lead author of the study, told Live Science. The trick, he said, is that ants and other metal-mouthed arthropods take advantage of their sharp rodents to precisely apply the right amount of cutting force to slice leaves or hide.
Schofield and his team knew from previous research that ant teeth contained a lot of zinc. But they weren’t sure exactly how these metallic atoms were arranged and how it helped ants bite. By examining the material composition of the teeth of leaf-cutting ants under an ion beam microscope before and after the bite, the researchers were able to calculate the hardness, sharpness and durability of the teeth.
An ant’s jaw, or mandible, is quite different from yours. “Ants don’t rely much on the mandibles to process food,” said Cristian Klunk, an environmentalist at the Federal University of Parana, Brazil, who was not involved in the study. But they use them for just about every other job, from defense to home improvement, so they need to keep them in top shape.
Your teeth are covered with a layer of enamel, a material rich in calcium which is the hardest substance in the human body. If you look at some enamel under an electron microscope, you will notice that calcium and phosphate molecules form a large crystal matrix around the carbon, hydrogen, and oxygen atoms. These crystals are what keeps teeth strong, but it’s also what keeps them from being sharp like razors.
In contrast, the tiny jagged “teeth” that line the inner edge of an ant’s mandible are coated with a smooth mixture of crisscrossing zinc proteins. This material, known as “heavy element biomaterial” (HEB), easily matches human tooth enamel for its strength. It also makes the ant tooth much better for slicing and cutting, as the lumpy calcium phosphate crystals found in the enamel cannot form extremely sharp edges – it would be like trying to make a knife “from it. of chunks of gravel, ”said Schofield. Zinc, however, does not form lumpy crystals; instead, it stays evenly distributed throughout the protein mix. This fine consistency takes into account the sharp edges of the teeth.
Metal reinforcements don’t stop at ant teeth. Other invertebrates also weave zinc or a similar metal, manganese, in their tiny tool kits. Schofield and his team found that giant clam worms encased jaws containing up to 18% zinc. Likewise, scorpion stings and spider fangs use a mixture of zinc and manganese atoms to ensure that these thin, needle-like structures can puncture hard flesh without breaking.
Schofield and his team calculated that adding zinc or manganese to an invertebrate’s exoskeleton reduced the force required to pierce hard material by an average of 60%. “Because zinc is more wear resistant,” Schofield said, “after a while it becomes a huge difference.”
The research was published on September 1 in the journal Scientific Reports.
Originally posted on Live Science.
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