KEY I, animals with 4 pairs of legs; spiders, mites, scorpions etc.

Abdomen with distinct joints

Abdomen without distinct joints

Abdomen elongated, forming tail with sting scorpions.
Abdomen not ending in tail..

Small animals (less than 5 mm),
With claws false scorpions.

Larger animals with very long legs harvestmen.

Body clearly divided into two parts spiders.

Very small animals with undivided body mites.