Arthropodous refers to animals that possess a segmented body, and jointed legs. Some possible synonyms for the word are arthropodan, arthropodan, and arthropodic. Additional synonyms could include invertebrate, bug-like, crawly, or creepy-crawly. Most arthropods belong to the class of animals called insects, which include creatures like spiders, centipedes, and millipedes. Arthropods have been around for at least 520 million years, and there are over a million species known to scientists today. These animals are an important part of our world, providing food for other organisms and playing important roles in ecosystems.