Arthropods are invertebrate animals
that have an external skeleton, a segmented body and jointed
appendages. The word "arthropod" comes from Greek and means jointed
feet. The Arthropod order includes insects, spiders and crustaceans.
Thus a butterfly and a crab are related. Go figure.
Arthropods are the most abundant animals on Earth. There are
over 1, 170,000 described species, which represents over 80% of all