Is an Insect an Animal? Where Insects Sit in the Animal Kingdom

An animal is a living thing made of many cells that eats other living things for energy and can move at some stage of its life. Scientists place an organism in the animal kingdom, called Animalia, using a few shared traits:

• Many cells: their bodies are built from many cells working together.
• No cell walls: unlike plants and fungi, animal cells have flexible outer layers.
• They eat food: animals cannot make their own food from sunlight.
• They move: almost all animals can move on their own during at least part of their life.
• They develop from an embryo: animal life starts from a fertilized egg.

Insects meet every one of these. A beetle, a butterfly and a bee all have many cells, eat other living things, move freely and grow from eggs. That makes each of them an animal.

Insects belong to the class Insecta, inside the larger group of jointed legged animals called arthropods. Scientists sort every living thing into a ranked system, from very broad groups to very specific ones. The table below follows the honey bee from the top of the animal kingdom down to its own species.

Insects are animals, but their bodies work very differently from mammals, birds and fish. The main difference is that insects have no backbone and wear their skeleton on the outside. Animals without a backbone are called invertebrates, and insects are the largest invertebrate group by far.

Insects share the arthropod group with several other animals, and comparing them makes the insect body plan easy to spot:

• Arachnids, such as spiders, ticks, mites and scorpions, have eight legs, two body parts and no antennae.
• Crustaceans, such as crabs, shrimp and pill bugs, usually have two pairs of antennae and many legs.
• Centipedes and millipedes have long bodies with many segments and far more than six legs.
• Insects have exactly six legs, three body parts, one pair of antennae, and are the only arthropods that can fly.

Many people grow up using the word animal to mean mammals, such as cats, dogs and cows. Insects look so different, with six legs, antennae and hard shells, that it can feel strange to put them in the same group. Everyday language adds to the mixup: people often say "animals and insects" as if they were separate groups. In science, though, insects are simply one kind of animal, the same way birds and fish are.

Yes, bugs are animals. In everyday speech, a bug can mean almost any small crawling creature, including insects, spiders and centipedes, and all of these are animals in the arthropod group. In science, a true bug is a specific type of insect in the order Hemiptera, such as a stink bug, bed bug or aphid. Spiders are animals too, but they are arachnids rather than insects. If you need to check a spider, the ScanaBug spider identifier can help.

Insects are the most varied group of animals on Earth. About 900,000 kinds of living insects have been named, and the Smithsonian estimates that around 10 quintillion individual insects are alive at any one time. Scientists believe many more species are still waiting to be discovered, with estimates of the true total ranging from about 2 million to as many as 30 million species. You can explore some of this variety, or identify your own find, with the ScanaBug insect identifier.