Wow. I feel like i should have known this before.
w h a t
This is kind of embarrassing...
Insects have a head, thorax and abdomen, and the thorax has three pairs of legs. They also eyes, antennae and mouthparts, the Explorit Science Center website points out. "The entire body is protected by a tough outer covering called an exoskeleton. Animals that share these characteristics are called insects. The group to which they belong is called the Insecta."
Spiders, as the Explorit Science Center explains, have two main body parts. "The body consists of a combined head and thorax called the cephalothorax, and the abdomen. The cephalothorax has the eyes, mouthparts (no antennae) and four pairs of legs. Animals that share these characteristics include ticks, mites, scorpions and spiders. The group is called the Arachnida."
w h a t
This is kind of embarrassing...