Insects are a type of invertebrate, meaning they don’t have an internal skeleton or backbone. Insects are also a type of arthropod. The term arthropod comes from the Greek word meaning “jointed feet,” and includes other similar animals such as crustaceans and arachnids. Insects are one of the largest classes of animals with over a million different species. Insects can be found in almost everywhere on earth. There are even five species of insects, such as pond skaters and ocean striders that are marine insects living on the surface of ponds and oceans, respectively.
Insects have an external skeleton, called an exoskeleton. They also have a three-part body including the head, thorax, and abdomen. The head includes the brain, a pair of compound eyes, mouth parts, and two antennae. The thorax has three pairs of jointed legs, and on some insects, one or two pairs of wings. The legs and wings provide insects the ability to walk, fly or occasionally even swim. The abdomen consists of many sections that may be fused together. The abdomen includes the the digestive, respiratory, excretory, and reproductive organs.