Arachnid, a general name for any animal that belongs to the class Arachnida. Arachnids include spiders, scorpions, harvestmen (or daddy longlegs), mites, and ticks. Arachnids are widely distributed over the world. Arachnids are invertebrates (animals without backbones). The body is made up of a cephalothorax (fused head and thorax) and abdomen, and usually six pairs of appendages. The first pair are the chelicerae, for catching and holding prey; those of spiders have poison sacs and fangs. The second pair are the pedipalps, for feeling and for manipulating prey. The other four pairs are for walking and—in some arachnids—for feeling.Spiders are common arachnids.
Arachnids make up the class Arachnida of the phylum Arthropoda.
Arachnids live nearly everywhere on Earth. They live in grassy fields and wet swamps. They live in hot, sandy deserts and in cool, dark caves. They live in tropical rain forests and on rocky mountaintops. In fact, arachnids live anywhere they can find food.
One arachnid you have probably seen is a spider. So far, scientists have found more than 30,000 kinds of spiders. And scientists think there are many, many more to be discovered.
As a group, arachnids are not in danger. Still, some arachnids are in trouble. Let’s look at two examples.
Many people wanted Mexican redknee tarantulas as pets. So many of these spiders were collected from the wild that they became threatened, or reduced in number. Today, laws protect these and other wild spiders that could also make good pets. Now pet spiders come from special breeding farms.
Six kinds of cave spiders in Texas are endangered. Polluted water is seeping into the caves where the spiders live. People are working to keep the caves clean. But these spiders face another danger. Fire ants have moved into their habitats. Fire ants not only eat the spiders’ food, but they also eat the spiders themselves.
Yes, some spiders are in danger. But many, many more are not. As they have done for millions of years, spiders will continue to weave and spin.