To date, scientists have identified about 1,744,204 (or 1.74 million) species.
That’s an impressive number, but a mere drop in the bucket compared to the number of species waiting to be discovered. Recent estimates place the number of species in the natural world anywhere between 8.7 million and over a trillion!
But the estimate includes plants, single-celled organisms, and even algae. Considering, a more appropriate question might be: How many animals are on Earth? And more importantly, just what is an animal? Are insects animals? Are bacteria? Let’s dig in a little deeper.
Are Insects Animals?
The answer to the first question — are insects are animals — is a resounding yes. Insects are animals. Now let’s dig into why.
Looking at our handy Animal Classification Guide, we see the highest level of taxonomy is ‘Domain.’
Archaea, Bacteria, and Eurkarya are the three taxonomic domains. The first two include mostly single-celled organisms, but only Eukarya features organisms with cellular nuclei. Does that mean everything in Eukarya is an animal? No. To reach that point we need to move down a rung to ‘Kingdoms.’
After all, trees are multiple cell organisms with nuclei, but a tree is obviously not an animal! That’s why at a ‘Kingdom’ level there is a classification known as Animalia, or animals. Species grouped in animals share a number of common traits:
- They reproduce sexually;
- Breath oxygen;
- Consume organic material; and
- Are able to move.
With a low number of exceptions, all animals meet these basic criteria. So the next time someone asks you, “are insects animals?” You can answer “yes,” because they reproduce sexually, breath oxygen, consume organic material, and are able to move.
What Percentage of the World’s Animals Are Insects?
Now that we’ve established that insects are animals, let’s dig into just what percentage of the animal kingdom is insects.
The short answer: A lot. Today there are about one million described species of insects. That’s about 70% of all animal species. In total, invertebrates (which includes arachnids, crustaceans, and other species) are 96% of all identified animal species.
When you compare the number of insects (under the ‘Class’ Insecta), you see the staggering biodiversity of insects.
Number of Species (Chapman, 2009)
- Insects: ~1,000,000
- Mammals: 5,487
- Birds: 9,990
- Reptiles: 8,734
- Fish: 31,153
- Amphibians: 6,515
Most importantly, the percentage of insects compared to other animals should continue to grow in the decades to come.
For example, researchers believe there may be about a dozen undiscovered/undescribed mammal species across the world. Put another way, 99.9% of mammal species have been discovered.
(Maybe Bigfoot is out there… but don’t hold your breath!)
A chart below compares just how massive the number of undiscovered insects may be!
|Group||Described Species||How Many Exist (Est)|
Today, about 70% of the world’s animals are insects. But in the future, insects and invertebrates could constitute more than 99% of all animal species!
What Is an Insect?
We’ve identified that:
- Insects are animals, and
- There are significantly more unknown insect species than there are mammals, reptiles, fish, birds, and amphibian species combined (and it’s not even close!)
So now let’s dive into what, exactly, constitutes an insect by looking at some incredible invertebrates.
Why the Millipede is Not an Insect
While we might call anything that crawls along the ground an ‘insect,’ in reality many small invertebrates aren’t.
Insects generally have six legs, three body segments, and two antennas. Compare this to the millipede which has up to 750 legs (fun fact: no millipede actually has a thousand legs!) and sometimes hundreds of body segments!
So while a millipede might be small, crawl on the ground, and have an exoskeleton, it’s actually not an insect but its own ‘Class’ named Diplopoda that includes more than 12,000 described species.
And here’s something mind-blowing: millipedes might be small today, but that’s wasn’t always the case. Three hundred million years ago, some millipedes grew larger than humans! Scientists theorize that their massive size was possible thanks to incredible levels of oxygen in the Earth’s atmosphere at the time.
The Asian Giant Hornet: An Insect
Is the Asian giant hornet an insect? The answer is “yes.” While the species flies, it has three body segments, six legs, two antennas, and three body segments.
In the United States alone there are more than 19,600 species of flies, 11,500 butterflies and moths, and 17,500 insects from the ‘Order’ that contains bees and wasps. That’s a lot of flying insects!
You’ve surely seen news stories about “murder hornets.” These giant wasps have been spotted across the United States in 2020 and raised significant media attention.
What’s the big deal? For starters, Asian giant hornets are voracious honeybee predators. A small group can completely wipe out a colony of 30,000-plus honeybees in just a couple of hours!
The Asian giant hornet isn’t really a murder hornet. About 40 people die a year form their stings in Asia, and most these deaths can be traced back to allergic reactions. However, their stringers are quite painful and best avoided!
How Many Insects Are in the World Today?
With insects on every non-Arctic landmass across the world, you might be wondering: “How many insects are in the world?”
It’s nearly impossible to count insects, but scientists estimate their populations and most believe that roughly 100 trillion ants roam the world! Put another way, their “biomass” may be as much as all humans combined — even with our weight differentials factored in!
The total number of every type of insect was estimated by the Smithsonian at 10 quintillion. If we write that out, the number of insects in the world today is 10,000,000,000,000,000,000 insects on Earth!
How are there so many insects in the world today? Well, just a single “super ant colony” stretches 3,700 miles along the Mediterranean coast, and ants aren’t even a fraction of total insects.
And there you have it, the low down on insects! Next up: New Monkey Species Found in Myanmar!