The term "insect" refers to a class of invertebrates within the arthropod phylum in the animal kingdom. The insecta class is massive; with more than 1 million species, it is estimated to represent 90 percent of multicellular life on Earth. Nevertheless, every insect species has several common features. All insects have a three-part body (head, thorax and abdomen), an exoskeleton made of chitin, compound eyes, one pair of antennae, and three sets of jointed legs.
Insects are remarkable creatures. While not all can fly, they are the only class of invertebrates that have developed flight. Some, such as termites, ants, wasps and bees, live in tight-knit social colonies. Many can swim, with some living almost all of their lives underwater. Across the class, their reproduction methods are vast, with some females not even needing male fertilization to reproduce. Insects as a whole are relatively weak and fragile.
Although many insects are deemed pests by humans, they actually perform many beneficial ecological roles. Insects help plants spread their pollen, thereby allowing more plants to grow. Some insects feed on others that can cause harm to agriculture. And were it not for insects, substances such as honey, silk, wax and lacqer would be nonexistent. (Photo: Wikimedia Commons)