How do the suction cups on lizards’ feet work and do they ever lose their suction?

The lizards that climb walls and ceilings don’t usually fall off.

But it’s not because they have great suction. Actually, they’re not really using suction at all.

Here’s how their feet work: On the bottom, there are dozens and dozens of grooves. (You can see them if you look closely at the bottom of a lizard in a glass-walled terrarium.)

On each of those little grooves that you can see, there are dozens more microscopic ones you can’t. And on each of those microscopic grooves are thousands of hair-like bumps.

So what good do bumps do on a smooth surface like glass? Well, if you look at the surface of glass through a microscope, you’ll see that it isn’t so smooth after all: its surface is covered with microscopic pits, bumps, and grooves.

To a lizard, tile, concrete, Sheetrock, and even glass all look like nice big rock climbing walls with plenty to hang on to. A lizard’s pads will grab onto the surface and hang on tightly, even if the lizard is scared, tired, sick, or dying.

In some cases even death isn’t enough to dislodge a lizard from a wall. Sometimes it takes hours for a dead lizard to drop because the feet are still clinging onto the tiny imperfections.