Have you ever wondered how water striders can walk on water? Wonder no longer!
Gerris lacustris, commonly known as the common pond skater or common water strider
You will need
- Thin wire (ours was 0.3 mm in diameter)
- Wire cutters
- Bowl
- Water
Safety
You’ll be using wire cutters in this activity. Take care and ask an adult to help if you’re unsure.
What to do
Cut 3 pieces of wire, each about 8-10 centimetres long.
Tightly twist the 3 wires together in the middle. This creates the water strider’s body and the 3 “legs” on each side.
Shape the water strider’s legs into a long, shallow “U” shapes. When you set it down on a flat surface all 6 legs should touch the ground.
Fill your bowl with water and gently place your water strider on the water’s surface.
Troubleshooting
If your water strider sinks, it’s probably because its weight isn’t spread evenly. Try taking it out of the water and placing it on a flat surface. Do all the legs touch the surface? Try adjusting the legs so they lie long and flat across the surface.
What’s happening?
Water striders take advantage of a special property of water called surface tension. Water is made of a bunch of molecules that are attracted to each other like magnets. This attraction forms a “skin” on the water’s surface that is strong enough to hold a small amount of weight. You can test this! What happens if you add weight by gently pushing on your floating water strider? What happens if you break the water’s surface by making it rain by splashing water from above?
To deal with rain, real water striders have another trick up their sleeve. Their legs are covered in tiny hairs that trap air, forming a cushion between the leg and the water. The air keeps the strider’s legs dry, even in a rainstorm. This hairy discovery is inspiring scientists to design new water-repellent materials.
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