insects are the most numerous animal category in the world. there is estimated to be over one million bugs per square mile of (american) forest. they are also a very important part of the ecosystem. if you relate speed to body size, the cheetah would not be the fastest land animal, the tiger beetle would. but the beetle only runs at about five miles per hour insects are also the spark of some horror movies, being so strange. insects are the class arthropods that have a chitinous exoskeleton, a three-part body (head, thorax, and abdomen), three pairs of jointed legs, compound eyes, and two antennae.