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What Are the Different Types of Arthropods?

Arthropods have six or more jointed legs and segmented bodies. They are found in water, on land and in the sky, comprising 90 percent of all animals species on Earth. Most arthropods are classified as either insects, arachnids or crustaceans and feature a chitin exoskeleton. Giant king crabs are grouped as arthropods, as are many microscopic insects. Scientists discover thousands of previously unknown arthropod species every year.

Insects
- Insects are by far the most populous species of arthropods, including ants, beetles, butterflies, dragonflies and grasshoppers. Over 1 million arthropodic insect species have been identified, and the number grows on a nearly daily basis. These insects are characterized by a triple-segmented body containing a head, thorax and abdomen. Insect arthropods have six or more legs, two antennae and lateral, compound eyes.
Crustaceans
- Crustaceans make up both the largest and smallest type of arthropods. Crustacean arthropods have 10 or more legs and two pairs of antennae, encompassing crabs, spiny lobsters, barnacles and shrimp. Over 44,000 species of crustacean arthropods have been identified, most of them aquatic.
Arachnids
- Arachnids have eight legs, and include spiders, ticks, mites and scorpions. The two body sections of an arachnid are known as the cephalothorax and abdomen. Over 65,000 arachnid species populate the Earth, and many of them are capable of secreting poison.

Insects & Science