Are Insects Animals?

Although people sometimes use animals informally to mean only vertebrates (animals with backbones) or even just mammals, in biology the term includes insects as well. Insects belong to the kingdom Animalia, along with mammals, birds, reptiles, amphibians, fish, octopuses, snails, jellyfish, worms, and many other groups. More specifically, insects are invertebrates (animals without backbones) and are part of the arthropod phylum, which also includes spiders, crabs, and centipedes.

In fact, insects are by far the most diverse group of animals on Earth. Scientists have described more than 1 million insect species—well over half of all known animal species—and many more remain undescribed. By comparison, there are only about 75,000 known species of vertebrates, including all mammals, birds, reptiles, amphibians, and fish combined. Insects are also astonishingly abundant. They inhabit nearly every terrestrial and freshwater environment on Earth, and the total number of individual insects at any given time is estimated to be in the quintillions (billions of billions). Ants alone are estimated to outnumber humans 2.5 million to 1. That’s a lot of animals.