Spiders and Their Webs

Eight legs and amazing silk

A spider sitting in the middle of its web is one of nature's best builders. But first, an important fact that surprises many people: a spider is not an insect! Spiders belong to a different group called arachnids, which also includes scorpions and ticks.

How to tell a spider from an insect

You can spot a spider with a quick check:

	Spider (arachnid)	Insect
Legs	8	6
Body parts	2	3
Antennae	None	Two
Wings	None	Often

So a spider has eight legs and just two body parts. An insect has six legs and three parts. To revise insect bodies, see our lesson on insect bodies: head, thorax and abdomen.

Making silk

The most amazing thing about spiders is silk. Spiders make silk as a liquid inside their bodies, then squeeze it out through tiny nozzles called spinnerets at the back of the abdomen. As the silk leaves the body and meets the air, it hardens into a thread.

Spider silk is incredible stuff. For its weight it is stronger than steel, yet it can stretch without snapping. Spiders use silk for many jobs:

• To build webs that trap food
• To wrap up prey like a parcel
• To make a safety line (so a spider can dangle and not fall)
• To wrap their eggs in a cosy silk sac

How an orb web works

The beautiful round web you see on a misty morning is called an orb web. The spider builds it in a clever order:

1. It releases a thread that the wind carries to a branch, making the first bridge.
2. It adds strong spokes that reach out like the lines on a bicycle wheel.
3. Finally it spins a spiral of sticky thread round and round to catch prey.

Why doesn't the spider get stuck? Only the spiral threads are coated in tiny drops of sticky glue. The spokes are dry. The spider walks carefully on the dry threads, and its feet have an oily coating, so it never gets caught in its own trap.

When an insect flies into the sticky spiral, it gets glued in place. The spider feels the web shaking through its legs, rushes over and wraps its meal in silk.

Not all spiders spin webs

Some spiders do not make webs at all. A wolf spider chases its prey across the ground, and a jumping spider pounces like a tiny cat, using its very sharp eyesight. These hunters still make silk for safety lines and egg sacs.

Why spiders are our friends

Many people feel scared of spiders, but spiders are mostly helpful. A single spider can eat hundreds of insects in a year, including flies and mosquitoes that bother us. Without spiders, there would be far more pest insects around. Spiders are also food for many birds, so they are an important part of the food chain.

Observe and investigate

1. Web hunt: on a cool, dewy morning, look for orb webs on bushes, fences or in corners. The dew makes the silk sparkle so you can see the spiral pattern.
2. Count the legs: if you find a spider (look, do not touch), count its legs. Eight legs and two body parts confirm it is a spider, not an insect.
3. Test for shaking: very gently touch the edge of an empty web with a blade of grass (when no spider is home). Imagine how a spider feels that wobble through its legs when an insect lands — that is how it knows dinner has arrived.

Spiders may have a spooky reputation, but they are skilled builders and helpful hunters that quietly keep pesky insects under control.