Month: October 2024

It can be startling to look at a world population counter. There are eight billion (and counting — fast) humans on Earth. That’s a lot. And humans, of course, have an enormous impact. However, we are far from the most abundant animal on the planet. In fact, mammals are at the bottom of the list, with only about 5,500 or so named species. 

On the other hand, scientists have identified about a million species of insects, and there are many insects that haven’t yet been identified, explains Scott Hoffman Black, entomologist and executive director of the Xerces Society, an organization dedicated to the conservation of invertebrates. Experts estimate that anywhere from a conservative four million to possibly as many as seven million species are yet to be identified.

So yes, the most abundant land animal is definitely an insect. But which one?

The Most Populated Animal in the World

According to an oft-told anecdote, the British evolutionary biologist J.B.S. Haldane was once asked what he could say about the nature of God based on his study of the natural world. Haldane responded dryly that the creator has “an inordinate fondness for beetles.” The story is most likely apocryphal but so delightful that it has been repeated for decades.

And indeed, there are a lot of beetles on the planet — by some estimates, approximately 350,000 described species. But they aren’t the most abundant land animals. There are a lot of ways to break this down, but if you go by either individual animals or biomass, which is basically weight, the honor almost certainly goes to ants.

The authors of a widely cited 2022 study estimated that there were 20 quadrillion (that’s 20 followed by 15 zeros) ants on Earth — and they were being conservative. Or if this helps you get your mind around the sheer number of ants, the total biomass of ants is greater than the combined biomass of all wild birds and mammals and is about 20 percent of the biomass of all humans on the planet, according to the study. 

Read More: An Ancient Ant Army Once Raided Europe 35 Million Years Ago

Why Are There So Many Ants in the World?

Phillip Barden studies ants (and other social insects) at the New Jersey Institute of Technology. He says the amazing success of ants is likely due to the fact that ants are social animals.

“Once you get out of this unitary system where it’s one individual collecting and foraging on its own, the race is on, and you get these massive colonies, some with tens of millions of workers,” he says.

Black adds that ants have adapted to almost all environments, from the high mountains to deserts, and have many different strategies for survival. They also have a very adaptable diet. Many ants are predators, eating other animals — and they’re good at it because they cooperate in getting food. Some ants eat seeds, and some grow a fungus they eat, basically practicing agriculture, as Barden puts it. 

This ability to adapt to whatever conditions they find themselves in is probably the reason ants have survived. Ants were present in the Cretaceous period, says Barden, but they made up no more than one percent of all the insects researchers have found in amber or fossil deposits. But after the K-T extinction at the end of the Cretaceous, some 65 million years ago, ants made up at least 10 percent and maybe as much as 30 percent of all insects.

And he adds, “If you go to a rainforest, the biomass of ants and termites today is greater than not only all insects, but all insects plus all vertebrates combined.”

Read More: 6 Unusual Traits of Animal Evolution

Could Ants Outlast Humans in a Mass Extinction?

Many experts argue that we’re in the midst of the sixth mass extinction. If that’s the case, how will ants fare? Almost certainly better than humans, says Black. In previous extinctions, insects have survived when many other groups didn’t, he says. And ants specifically?

Barden points out that many types of ants do exceptionally well in places that humans have disturbed, such as golf courses and lawns.

“I think we’re going to see, and will continue to see, that a handful of ant species that are really well suited to disturbed habitats are going to continue to be really successful. And so instead of finding many dozens or hundreds of species in certain places, we might find just a few, but in those places, those species will be highly abundant,” says Barden.

 So have some respect the next time you come across an ant in your cupboard. 

Read More: What Happens If a Tiny Insect Goes Extinct? Should We Even Care?

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

Avery Hurt is a freelance science journalist. In addition to writing for Discover, she writes regularly for a variety of outlets, both print and online, including National Geographic, Science News Explores, Medscape, and WebMD. She’s the author of Bullet With Your Name on It: What You Will Probably Die From and What You Can Do About It, Clerisy Press 2007, as well as several books for young readers. Avery got her start in journalism while attending university, writing for the school newspaper and editing the student non-fiction magazine. Though she writes about all areas of science, she is particularly interested in neuroscience, the science of consciousness, and AI–interests she developed while earning a degree in philosophy.

Fusion energy has the potential to be an effective clean energy source, as its reactions generate incredibly large amounts of energy. Fusion reactors aim to reproduce on Earth what happens in the core of the Sun, where very light elements merge and release energy in the process. Engineers can harness this energy to heat water and generate electricity through a steam turbine, but the path to fusion isn’t completely straightforward.

Controlled nuclear fusion has several advantages over other power sources for generating electricity. For one, the fusion reaction itself doesn’t produce any carbon dioxide. There is no risk of meltdown, and the reaction doesn’t generate any long-lived radioactive waste.

I’m a nuclear engineer who studies materials that scientists could use in fusion reactors. Fusion takes place at incredibly high temperatures. So to one day make fusion a feasible energy source, reactors will need to be built with materials that can survive the heat and irradiation generated by fusion reactions.

Fusion Material Challenges

Several types of elements can merge during a fusion reaction. The one most scientists prefer is deuterium plus tritium. These two elements have the highest likelihood of fusing at temperatures that a reactor can maintain. This reaction generates a helium atom and a neutron, which carries most of the energy from the reaction.

Humans have successfully generated fusion reactions on Earth since 1952– some even in their garage. But the trick now is to make it worth it. You need to get more energy out of the process than you put in to initiate the reaction.

Fusion reactions happen in a very hot plasma, which is a state of matter similar to gas but made of charged particles. The plasma needs to stay extremely hot – over 100 million degrees Celsius – and condensed for the duration of the reaction.

To keep the plasma hot and condensed and create a reaction that can keep going, you need special materials making up the reactor walls. You also need a cheap and reliable source of fuel.

While deuterium is very common and obtained from water, tritium is very rare. A 1-gigawatt fusion reactor is expected to burn 56 kilograms of tritium annually. However, the world has only about 25 kilograms of tritium commercially available.

Researchers need to find alternative sources for tritium before fusion energy can get off the ground. One option is to have each reactor generating its own tritium through a system called the breeding blanket.

The breeding blanket makes up the first layer of the plasma chamber walls and contains lithium that reacts with the neutrons generated in the fusion reaction to produce tritium. The blanket also converts the energy carried by these neutrons to heat.

The fusion reaction chamber at ITER will electrify the plasma.

Fusion devices also need a divertor, which extracts the heat and ash produced in the reaction. The divertor helps keep the reactions going for longer.

These materials will be exposed to unprecedented levels of heat and particle bombardment. And there aren’t currently any experimental facilities to reproduce these conditions and test materials in a real-world scenario. So, the focus of my research is to bridge this gap using models and computer simulations.

From the Atom to Full Device

My colleagues and I work on producing tools that can predict how the materials in a fusion reactor erode, and how their properties change when they are exposed to extreme heat and lots of particle radiation.

As they get irradiated, defects can form and grow in these materials, which affect how well they react to heat and stress. In the future, we hope that government agencies and private companies can use these tools to design fusion power plants.

Our approach, called multiscale modeling, consists of looking at the physics in these materials over different time and length scales with a range of computational models.

We first study the phenomena happening in these materials at the atomic scale through accurate but expensive simulations. For instance, one simulation might examine how hydrogen moves within a material during irradiation.

From these simulations, we look at properties such as diffusivity, which tells us how much the hydrogen can spread throughout the material.

We can integrate the information from these atomic level simulations into less expensive simulations, which look at how the materials react at a larger scale. These larger-scale simulations are less expensive because they model the materials as a continuum instead of considering every single atom.

The atomic-scale simulations could take weeks to run on a supercomputer, while the continuum one will take only a few hours.

All this modeling work happening on computers is then compared with experimental results obtained in laboratories.

For example, if one side of the material has hydrogen gas, we want to know how much hydrogen leaks to the other side of the material. If the model and the experimental results match, we can have confidence in the model and use it to predict the behavior of the same material under the conditions we would expect in a fusion device.

If they don’t match, we go back to the atomic-scale simulations to investigate what we missed.

Additionally, we can couple the larger-scale material model to plasma models. These models can tell us which parts of a fusion reactor will be the hottest or have the most particle bombardment. From there, we can evaluate more scenarios.

For instance, if too much hydrogen leaks through the material during the operation of the fusion reactor, we could recommend making the material thicker in certain places or adding something to trap the hydrogen.

Designing New Materials

As the quest for commercial fusion energy continues, scientists will need to engineer more resilient materials. The field of possibilities is daunting – engineers can manufacture multiple elements together in many ways.

You could combine two elements to create a new material, but how do you know what the right proportion is of each element? And what if you want to try mixing five or more elements together? It would take way too long to try to run our simulations for all of these possibilities.

Thankfully, artificial intelligence is here to assist. By combining experimental and simulation results, analytical AI can recommend combinations that are most likely to have the properties we’re looking for, such as heat and stress resistance.

The aim is to reduce the number of materials that an engineer would have to produce and test experimentally to save time and money.

Sophie Blondel is a Research Assistant Professor of Nuclear Engineering at the University of Tennessee. This article is republished from The Conversation under a Creative Commons license. Read the original article.