Linked from
The 38 pages that link to Spider, each with the reason it gives.
Sea spiderCompared with: Despite their name, sea spiders are not members of this spider order.
SolifugaeCompared with: Solifuges resemble spiders but form a separate order and lack spinnerets.
AmblypygiCompared with: Amblypygids lack the silk-producing spinnerets characteristic of spiders.
OpilionesCompared with: Spiders have distinct body regions and silk organs, unlike harvestmen.