Are Spiders Insects?

No, spiders are not insects. Spiders have eight legs and two body segments. They belong to the class Arachnida.  Insects, however, have six legs and three body segments. Insects belong to the Class Insecta.

There are more than 45,000 identified species of spiders. They have bodies that look very different from insects. Instead of three parts – a head, a thorax, and an abdomen, they only have two. Spiders have a head, called a “cephalothorax,” and an abdomen.

Spiders also have many eyes to help them find and capture food. Most spiders have eight eyes, and they can be arranged in different ways depending on how they hunt. Some spiders only have six eyes. Many pairs of eyes arranged around their cephalothorax allows them to see their food and to be sure they don’t become food themselves.

All spiders can make silk, and some spiders weave webs to catch their prey. These webs can be beautifully intricate with spiral patterns and embellishments of thicker silk, messy collections of sticky silk, and even small webs held in the arms of the spiders. The silk used to build these marvels comes from a special set of glands on spider abdomens called spinnerets. These glands can make both sticky and smooth silk, depending on what the spider needs. 

Orb-weaving spiders construct intricate patterns to catch prey that become entrapped in the sticky spiral silk, and they have done so for more than 400 million years. These spiders carefully build webs with mooring and framework threads anchoring the web and providing stability, radial threads forming the framework of the web, and viscid threads making the sticky spiral section. 

Certain types of spiders, like funnel-web and trap-door spiders, build their webs near the ground and wait for small insects to fall into the web where the spiders can grab them.

Other spiders don’t spin webs at all. These spiders prefer to hunt on the ground, usually at night. They have keen eyesight and can dart quickly to capture their prey.  Amazingly, some female wolf spiders carry their babies on their backs until they are large enough to fend for themselves.

Whether on the ground or in a web, spiders are important for controlling populations of insects and pests. While most spiders feed on small insects and arthropods, some are large enough to feed on small amphibians, reptiles, and even fish. The fishing spider has adapted to walk on the surface of the water to hunt aquatic insects and small fish.

While spiders may have intimidating appearances, very few are actually harmful to humans. Some spiders are able to bite humans but without major consequences. However, in North America, two groups, the widow spiders and the recluse spiders, can cause harm. Overwhelmingly, spiders are shy and uninterested in interacting with or attacking humans. They are important for pest control, including mosquitoes, and are unlikely to cause major harm.