Are insects animals?

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key point:
  • Insects are considered animals because they reproduce sexually, breathe oxygen, consume organic matter, and are able to move.
  • There are about 1 million species of insects, accounting for about 70% of all animal species. However, scientists believe there may be as many as 5 million insect species in existence!
  • Generally, insects have six legs, three body segments, and two antennae. The millipede is not considered an insect because it has as many as 750 legs and sometimes hundreds of body parts. It's in its own class called Diplopoda, which includes more than 12,000 described species.

To date, scientists have identified approximately 1,744,204 (or 1.74 million) species of insects.

That's an impressive number, but a drop in the bucket compared to the number of species waiting to be discovered. Recent estimates put the number of species in nature at anywhere from 8.7 million to over a trillion !

But estimates include plants, single-celled organisms, and even algae. Come to think of it, a more appropriate question might be: How many animals are there on Earth ? More importantly, what is an animal? Are insects animals or bacteria? Let's dig a little deeper.

Various collected insects fixed in a box with a magnifying glass
Scientists believe there are between 8.7 million and 1 trillion species of insects on Earth—and they do fall under the animal category.

©ju_see/Shutterstock.com

Are insects animals ?

Yes, insects are definitely animals. Now let's dig into why.

Looking at our handy guide to taxonomy of animals, we can see that the highest level of taxonomy is "domain".

Animal taxonomy chart showing groups of animals
According to their taxonomy, insects have been identified as animals.

© Erebor Mountain/Shutterstock.com

Archaea, Bacteria, and Eukarya are three taxonomic domains. The first two mainly include single-celled organisms, but only eukaryotes have a nucleus. Does this mean that everything in Eukarya is an animal? No. To get to this point, we need to move down one rung to "Kingdom".

Trees are, after all, multicellular organisms with nuclei, but trees are clearly not animals! That's why at the "kingdom" level there is a classification called Animalia or Animalia. Species among animals share many common characteristics:

  • sexual reproduction
  • breathing oxygen
  • consumption of organic materials
  • able to move

With few 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, breathe oxygen, consume organic matter, and are able to move.

How many animals in the world are insects?

Now that we've established that insects are animals, let's delve into what percentage of the animal kingdom insects make up.

Short answer: a lot. Today, approximately 1 million species of insects have been described. This accounts for about 70 percent of all animal species. Collectively, invertebrates (including arachnids, crustaceans, insects, and other species) account for 96 percent of all identified animal species.

When you compare the numbers of insects (under the class "Insecta"), you see the amazing biodiversity of insects.

Various insects on white background.
Collectively, invertebrates, which include arachnids, crustaceans, insects and other species, account for 96 percent of all identified animal species.

©Protasov AN/Shutterstock.com

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 proportion of insects compared to other animals should continue to grow in the coming decades. Climate change, in particular, is a major factor in the estimated growth of insect populations. While other animals will have to deal with loss of habitat and food sources due to higher temperatures and more extreme weather events, insects will thrive. Scientists believe that as global temperatures rise, so will insect metabolism and reproductive rates.

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For example, researchers believe there may be about a dozen undiscovered/undescribed mammal species worldwide. In other words, 99.9% of all mammalian species have been discovered.

(Maybe Bigfoot is out there… but don't hold your breath!)

The chart below compares how many undiscovered insects there might be!

group species described How many exist (estimated)
mammal 5,487 ~5,500
reptile 8,734 ~10,000
fish 31,153 ~40,000
birds 9,990 >10,000
amphibians 6,515 ~15,000
insect ~1,000,000 ~5,000,000
Data: Number of extant species

Today, about 70 percent of the world's animals are insects. But in the future, insects and invertebrates could make up over 99% of all animal species!

You might be wondering — how did scientists make such large estimates of undiscovered insects? On the one hand, progress has provided better statistical tools and new data. There are an estimated 5.5 million species of insects, but only 1 million of them have been named. It is estimated that there are as many as 30 million species of insects in existence. What a discovery! Scientists believe that 80 percent of existing insects remain undiscovered.

So which insects dominate in numbers? Believe it or not, the largest insect family is the beetle family. There are an estimated 1.5 million species of beetles alone! But even that number isn't a given—according to one study, there could be more than 2 million species. Of these species, scientists have only described 350,000 different beetle species. So let's narrow all this down to raw numbers your brain can process: Beetles are estimated to make up at least 40% of the insect kingdom (and this is a conservative estimate – some experts put the figure at 50%)!

What are insects?

We have identified:

  1. insects are animals, and
  2. There are more unknown species of insects than mammals, reptiles, fish, birds and amphibians combined (and not even close!)

Insects are part of a family of animals called arthropods. Other arthropods include: crabs, crayfish, millipedes, centipedes, spiders and scorpions. The word "arthropod" literally means "jointed foot". What all arthropods have in common is that they have exoskeletons, segmented bodies, bilateral symmetry (meaning that both sides of the animal are identical), and pairs of articulated appendages (legs, arms, antennae, etc.). Insects differ from other arthropods by the number of segmented body parts or paired appendages they have.

To reiterate, this insect has three segmented body parts – head, thorax, abdomen. A crustacean differs from an insect in that it has only two segmented body parts — a head and a thorax. Most people already know why spiders aren't insects— insects only have six legs , while all spiders have eight.

So now let's take a deeper look at what insects really are by looking at some incredible invertebrates.

Why Millipedes Are Not Insects

While we might call anything that crawls on the ground an "insect," many small invertebrates are not.

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Insects usually have six legs, three body parts and two antennae. Compare that to millipedes, which have as many as 750 legs (fun fact: no millipede actually has 1000 legs!), and sometimes hundreds of body parts!

So while a millipede may be small, crawl on the ground, and have an exoskeleton, it's not actually an insect, but belongs to its own "class" called Diplopoda, which includes more than 12,000 described species.

Here's something exciting: Millipedes may be tiny today, but that wasn't always the case. 300 million years ago, some millipedes grew bigger than people! Scientists speculate that their enormous size was possible due to the incredible amount of oxygen in Earth's atmosphere at the time.

A millipede curls up on a piece of wood.
Millipedes, technically an arthropod rather than an insect, are still considered part of the animal kingdom. Three hundred million years ago, some millipedes grew larger than humans.

© Vikorn Phartchayapruti/Shutterstock.com

Asian giant hornet : an insect

Is the Asian giant hornet an insect? The answer is "yes". When this species flies, it has three body segments, six legs, two antennae and three body segments.

In the United States alone, there are more than 19,600 species of flies, 11,500 species of butterflies and moths, and 17,500 species of insects from the "order", which includes bees and wasps. That's a lot of flying insects!

You've no doubt seen the news reports about the "Killer Hornet." These giant hornets have been spotted all over the United States in 2020 and have garnered a lot of media attention.

What's the big deal? First, the Asian giant hornet is a voracious honeybee predator. A small group of people can wipe out over 30,000 bees in just a few hours!

The Asian giant hornet is not really a killer hornet. About 40 people die each year from stings in Asia, most of which can be traced to anaphylaxis. However, their stringers are a pain in the ass and best avoided!

An Asian giant hornet resting on a tree branch.
Asian giant hornets are classified as insects because they have three body parts and six legs. They are very deadly animals, able to wipe out colonies of more than 30,000 bees in just a few hours.

© Ruzy Hartini/Shutterstock.com

What is an animal?

We've looked at the definition of an insect in detail, and how it differs from other arthropods. But what is an animal?

To recap, these basic characteristics exist in animals: they reproduce sexually; they breathe oxygen;
They consume organic matter; they are able to move. Species classified as animals also share other characteristics:

  • animals are multicellular
  • They have a eukaryotic cell structure
  • They go through the blastocyst stage of development
  • they have advanced nervous systems

But some of these features are shared by other organisms in two other kingdoms (Plantia and Fungi). For example, parasitic plants can survive on nutrients from the host plant. Some plants can also reproduce sexually and asexually.

Mobility is one of the characteristics that distinguish animals from other living things. Animals have well-developed muscles, which enable them to travel. While many can move great distances, some animals, such as sponges, are still classified as animals because they have been found to be able to move short distances. The ability of animals to travel allows them to find mates to reproduce, find food, and escape or hide from predators.

9 different types of insects

There are 9 basic orders of insects:

  1. Coleoptera – beetles
  2. Dictoptera – cockroaches and praying mantises
  3. Diptera – flies
  4. Ephemera – Mayfly
  5. Lepidoptera – butterflies and moths
  6. Hymenoptera – ants, bees and wasps
  7. Odonata – Dragonflies and Damselflies
  8. Orthoptera – grasshoppers and katydids
  9. Phasmida – stick insect
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This is not an exhaustive list of all insect types – there are actually nearly 20 more. Other orders include insects such as bedbugs, fleas, termites, earwigs, sucking lice, and silverfish. The list goes on and it's no wonder since we've said there are over 1 million identified insect species!

Bugs vs. Insects: What's the Difference?

Finally, you may be asking yourself "What's the difference between an insect and a bug?" Like insects, bugs are definitely animals, but you may be wondering how a bug and an insect are different.

The word "error" is usually informal. Many people will simply use the term "bug" to refer to any reptile with legs. By this definition, even animals that are not insects (like the millipede example above) qualify as bugs.

The more formal definition of a bug is a piercing and sucking insect with mouthparts. The order of insects that falls under the definition of the word "bug" is Hemiptera. Under this more formal definition, examples of bugs include everything from bedbugs to cicadas to aphids, which are small, sap-sucking insects.

How many insects are there in the world today?

With insects on every non-Arctic continent in the world, you might be wondering: "How many insects are there in the world?"

The number of insects is almost impossible, but scientists have estimated their numbers, and most agree that there are about 100 trillion ants roaming the world! In other words, they probably have as much "biomass" as all humans combined – even accounting for our differences in weight!

The Smithsonian estimated the total number of each insect to be 10 quintillion. If we write it out, the number of insects in the world today is 10,000,000,000,000,000,000 insects on Earth!

How can there be so many insects in the world today? Well, there's only one "super ant colony" stretching 3,700 miles along the Mediterranean coast, and ants aren't even a fraction of the insect population.

Ant trails on a dirt road with two large rocks.
Ants are one of the most abundant insect groups on Earth. There are believed to be around 100 trillion of these animals roaming the world.

© Elizaveta Galitckaia/Shutterstock.com

This is the inside story of insects! Next: New monkey species discovered in Myanmar!

next…

  • Is a Spider an Insect Let’s solve this question once and for all by taking a deeper look at the characteristics of insects vs spiders.
  • Discover 15 Amazing Animals That Eat Insects Some animals survive on insects. Here is a list of 15 that can do just that.
  • Killer Bees vs Honey Bees: What's the Difference? What's the Difference Between the Dreaded Killer Bee and the Common Bee? Read this fascinating article to find out.

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about the author


Emily is an editor and content marketing specialist for five years. She grew up in rural Pennsylvania, where you can regularly encounter anything from elk to black bears to otters. Over the years, she has raised livestock, small animals, dogs, cats, and birds, and this is where she learns most of her knowledge about animals of all kinds, and what makes her a pet groomer and pet store manager. She now has three rescue cats and two high-need Pomeranian mixes to shoulder her love and attention.

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