Although scientists don't know exactly how many species of arachnids there are alive today, their best guess puts the species count in the ballpark of 100,000 of which, more than 40,000 are spiders. Since that means nearly half of all archnids are spiders, it's easy to forget the other lesser-known eight-legged creatures that belong to the group.
Arachnids include about a dozen subgroups, many of which are obscure groups that most people have never heard of. But there are a few that stand out. The most well-known group is of course, the spiders. But odds are you've probably also heard of a few other arachnid groups. They include: harvestmen, ticks and mites, and scorpions.
Scorpions are easy to recognize thanks to their segmented tails that curl up to a venomous point. Ticks and mites are generaly very small, measuring just a few millimeters in length. Harvestmen are perhaps the group that is most commonly mistaken for spiders. There are about 6,300 species of harvestmen (also known as daddy-long-legs). Members of this group have very long legs and their abdomen and cephalothorax are almost completely fused.
So next time you see something with eight legs, don't immediately assume it's a spider.
Photo © Steve Taylor / Getty Images.
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