A Spider's Ability to Stick and Not Get Stuck

Why don’t spiders get caught in their own web?

Orb-weavers, or spiders that make webs, use their silk to catch prey. When a fly or moth comes into contact with a spider’s web, they become stuck. A spider on the other hand, can rush across the web with ease to enjoy the freshly caught meal without fear of being trapped itself. Have you ever wondered why spiders don’t get caught in their own web?

At Science City’s Nature Works, we have our very own Chilean Rose-Haired Tarantula (Grammostola rosea) named Carmen. She isn’t an orb-weaver and doesn’t make webs to catch her prey. However, she does spin sticky silk to create “trip lines” near the burrow where she lives to let her know when a predator or prey is nearby.

Supplies

Double-sided tape

paper

oil (baby oil, cooking oil etc.)

Stick Two Pieces of Double-sided Tape Next to Each Other on a Piece of Paper

Touch Only One Strip of Tape With Your Index Finger. What Happened? This Is Similar to How Insects Get Stuck in a Spider’s Web

Now Dab Your Index Finger in a Little Bit of the Oil

Touch the Other Piece of Tape With Your Oily Finger. Did Your Finger Get Stuck to the Tape?

Explanation

This activity is similar to how a spider can move across its own web without getting stuck. There are two main reasons for this. Only the tiny hairs on the tip of the spider’s leg make contact with the sticky silk. This reduces the surface area that is in contact with the sticky web. Also, the tiny hairs on a spider are coated with a non-stick substance similar to the oil we used in this activity.