Spiders

Spiders are arthropods belonging to the order Araneae within the class Arachnida. Unlike insects, they have eight legs rather than six, lack wings and antennae, and have a body divided into two main regions: a fused head and thorax, and an abdomen. Nearly all spiders are predators, and most produce silk from spinnerets at the rear of the abdomen. This silk is used to build webs, line burrows, wrap prey, and form egg sacs. Tens of thousands of spider species have been described, found on every continent except Antarctica.

Most spiders capture prey using venom delivered through fangs, which subdues insects and other small animals. The great majority are harmless to humans, but a few species carry venom strong enough to cause medical concern. The black widow, recognised in some species by a red marking on the underside of the abdomen, produces a potent neurotoxic venom. Tarantulas are large, hairy spiders that, despite their fearsome appearance, are generally not dangerous to people; many use defensive hairs rather than potent venom. Crab spiders, named for their sideways gait, often ambush prey on flowers instead of building webs.

Spiders are ecologically valuable because they control populations of insects, including many pests. Their silk, hunting strategies and venom have made them subjects of scientific study, and their diversity of form and behaviour ranges from web-spinning orb weavers to active hunters that stalk or ambush their prey.

Frequently asked questions

Are spiders insects?

No. Spiders are arachnids, with eight legs and two body regions, while insects have six legs and three body regions. Spiders also lack wings and antennae.

Are most spiders dangerous to humans?

No. The vast majority of spiders are harmless. Only a few species, such as some black widows, have venom strong enough to affect people.

What do spiders use silk for?

Spiders use silk to build webs, wrap and store prey, line burrows, produce draglines, and protect their eggs in silk sacs.