Main Characteristics of Arachnids

There are 110,000 species of arachnids.
51,000 of them are spiders.
All arachnids have eight legs. Insects only have six.
Arachnids don't have a good sense of sight, but they do have an excellent sense of touch.
Arachnids have a forebody and an abdomen. Most other insects have three body sections.
Spiders have jaws and venom glands.
Not all spiders build a web of fine threads.
Threads made from spider silk are four to five times more robust than threads made from steel.
Arachnids also include scorpions and ticks.
Scorpions have two claws and a poisonous stinger.

Arachnid Family Tree