Heavy Metals Give Ants a Powerful Bite

A combination of metal atoms and natural proteins is the secret behind the super-strong jaws, claws and stingers of some tiny animals

A reddish orange leafcutter ant with large front mandibles on a green leaf
Heavy metal-fortified mandibles help leafcutter ants save energy and muscle mass. Andreas Kay via Flickr under [CC BY-NC-SA 2.0]

Leafcutter ants use their powerful jaws to slice vegetation, scorpions rely on sharp stingers to puncture a predator’s thick skin, and spiders need strong fangs to devour their meals. New research reveals the secret behind some tiny creatures’ super-durable appendages: heavy metal atoms.

University of Oregon physicist Robert Schofield and his colleagues examined ant teeth, spider fangs, scorpion stingers, marine worm jaws, and other arthropod appendages under a special microscope, reports Rahul Rao for Popular Science. Many of these animals are using their pinchers, teeth or stingers in life-or-death situations, when durability and strength are paramount. When scientists looked at the jaws of a leafcutter ant species called Atta cephalotes, they could see a thin, even disbursement of heavy metal atoms like zinc and copper mixed with natural proteins.

Fortifying certain body parts with these metals provides “the kinds of properties that you want in a knife or needle,” says Schofield to Jake Buehler for Science News.

Scientists already knew that some tiny creatures had certain body parts infused with zinc, copper, and manganese, but it wasn’t clear how the metals related to other durable proteins, reports Carrie Arnold for National Geographic. In the new study, published this month in Scientific Reports, the team looked at proteins and metals at a molecular level and found metal atoms woven into the proteins to create a super-strong composite material.

The even spread of atoms was key because “chunks of mineral limit how sharp the tool can be,” says Schofield to Science News.

When compared, metal-infused body parts were stronger and more resistant to damage than the calcium-based structures that other species use. Standard “biomineralized” body parts like a human’s teeth or a tortoise’s shell can break more easily and may be less energy-efficient to wield.

In the case of the leafcutter ant, the team estimates that their fortified jaws cut and puncture with 40 percent less energy and muscle mass than a metal-free mandible. The study looked at just a handful of species, and some scientists suspect others out there are also employing this metal-infusion trick.

“This study is a nice look at how this occurs across a range of organisms, and it may be more common than we think,” says Stephanie Crofts, a biologist at the College of the Holy Cross in Massachusetts who wasn’t involved in the work, to National Geographic.

Schofield is optimistic that the recent discovery could lead to technological and medical advances. The specific woven structure of natural proteins and heavy metals could be used as a roadmap to create new materials that balance strength, rigidity and weight.

“Human engineers might also learn from this biological trick,” he said in a statement. “While there are much harder engineering materials, they are often more brittle.”

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