"ARTH-ro-podd" sounds like a multi-footed animal that has a painful joint disease.

Check out some arthropods to see what differences and similarities they have. What the heck are they? The encyclopedia says that arthropods include insects, crustaceans, arachnids, and myriapods. Those worms with lots and lots of feet are also in this group. Arthropods have a horny, segmented external covering and jointed limbs.

Examine various arthropods to determine similarities among them. You might observe a sowbug (crustacean), a spider (arachnid), and an insect, for instance. Doesn't it seem strange to refer to a spider as an "animal?" Actually, living things are divided into two main groups: plants and
animals. If it is alive, and it isn't a plant, it is an animal. That includes snails, bugs, fish, and elephants.

You will find that most arthropods live on land, although some live on (or in) water. Most of them have a hard exterior body covering, called an exoskeleton. As they grow, they have to shed their exoskeleton so they can get a new one that fits better. They are invertebrates, which means they do not have bones. They have pairs of jointed, movable appendages (legs) for locomotion, and they have pairs of antennae (sensory organs on stems). They hatch from eggs.

What kinds of arthropods would live in water? Are crabs arthropods? Yes, and so are lobsters and shrimp. Altogether approximately 900,000 species of arthropods have been identified.