Logo: Backyard Bugs

How are insects classified?

One defining characteristic is how many legs.

  • Do you know the difference between an arachnid and an insect?
  • Have you ever wondered how many legs spiders have?
  • For answers to these questions and more keep reading...

6 Legs or 8 Legs

Arthropods are a group of invertebrates (animals with no backbone) that have jointed legs, segmented bodies, and hard, protective coverings called exoskeletons. Arthropods include such animals as insects, spiders, ticks, centipedes, millipedes, crayfish, lobsters, mites, and scorpions.
One class of arthropods is the arachnids which include spiders, scorpions, and mites. Spiders have two main body parts and eight legs.

Insects make up another class of arthropods. Insects are made up of three main body parts. The head is the first of an insect's three main body parts. It contains the antennae (sensory organs used to smell, taste, feel, and sometimes hear), compound eyes which are made up of many tiny units, and the mouthparts including the mandibles, or jaws, of an insect. The thorax is the middle of an insect's three body parts. The six legs and wings are attached to it. The abdomen is the last of an insect's three main body parts.

Insects go through metamorphosis which is the change of an insect (or other animal) from one form to another as it develops into an adult. Some insects go through a three-stage life cycle called incomplete or gradual metamorphosis: egg-nymph-adult. Others go through a four-stage complete metamorphosis: egg-larva-pupa-adult.

Check here for more information on Insect Orders


More About Bugs More About Butterflies Resources Glossary Order Video