Are Insects Animals? Yes, and here’s why
Insects are fascinating creatures that can be found all around you every single day. But, are insects animals? To answer this question we must first determine what the word "animal" actually means.
According to Merrium-Webster dictionary, animal is a noun and is defined as: "any of a kingdom (Animalia) of living things including many-celled organisms and often many of the single-celled ones (as protozoans) that typically differ from plants in having cells without cellulose walls, in lacking chlorophyll and the capacity for photosynthesis, in requiring more complex food materials (as proteins), in being organized to a greater degree of complexity, and in having the capacity for spontaneous movement and rapid motor responses to stimulation".
An animal is any living thing that's not a plant. So, yes, insects are animals. But how do you tell the difference between other animals and insects?
What is an insect?
We've determined that animals are any living thing that is not a plant. But how do you tell an insect apart from other animals?
First, insects are members of the phylum Arthropoda, or arthropods. Arthropods are invertebrates that have an exoskeleton, jointed appendages, and a segmented body. Arthropods include insects, arachnids, myriapods, and crustaceans.
Second, within the phylum Arthropoda, there is a subphylum, called Hexapoda, which includes Collembola (springtails), Protura (coneheads), Diplura (two-pronged bristletails), and insects. Members of the subphylum Hexapoda can be indentified by three pairs of legs and a consolidated thorax.
Insects meet all the criteria for Arthropoda and Hexapoda, plus they have a chitinous exoskeleton, a three part body (head, thorax, and abdomen), three pairs of jointed legs, compound eyes, and one pair of antennae. Even the word insect comes from the Latin word insectum, which means "with a notched or divided body".
Insects are also the only invertebrates that have developed flight. So if you're looking at a bug flying (not gliding) in your backyard and wondering if it's an insect, it is. Plus, all true bugs (Hemiptera) are insects.