Insects are members of the phylum Anthropoda and are characterized by their three pairs of jointed legs, segmented bodies, exoskeleton, one pair of antennae, and usually one or two pairs of wings. One million different species of insects have been named and discovered, but scientists estimate that at least 4 million others have yet to be named. Insects live in every habitat on earth, although very few live in water, with the oceans and lakes being dominated by other anthropods, the crustaceans. Insects are vital to every ecosystem, by being responsible for important roles such as pollination, decomposing plant and animal matter, and providing a source of food. With currently 10 quintillion insects on the globe, it is estimated that insects make up 90% of all animal life on earth.
Insects are able to eat a wide variety of food. About half of insect species are vegetarians and eat leaves, roots, seeds, nectar, or wood. Other species like praying mantises are predators and hunt other small insects. Fleas and lice are parasites and are able to feed on the flesh and blood of larger animals without killing them.
Insects have 6 legs in total – 3 pairs of jointed legs. Each pair of legs is attached to a body segment. One pair of legs is attached to the prothorax, another pair is attached to the mesothorax, and the last pair to the metathorax.
Insects that are attracted to light are considered positively phototactic. Although it is not known exactly why insects are attracted to light, it is believed that lights act as a navigational guide. Many insects guide themselves by keeping a natural light source such as the sun or moon at a constant angle, and get confused by any artificial light source.