A spiracle is a small opening that certain animals use for breathing. Many insects have spiracles along the sides of their bodies: tiny holes that let air flow directly into their breathing tubes. If you look closely at a caterpillar or grasshopper, you might spot these small dots running down its sides.

Sharks and rays also have spiracles, though theirs work differently. These fish have spiracles behind their eyes that draw in water, which then flows over their gills so they can breathe. This design helps bottom-dwelling rays breathe while they rest on the ocean floor: instead of sucking in sandy water through their mouths, they pull cleaner water through their spiracles.

Some people also use the word for the breathing opening on top of a whale’s head, though we usually call it a blowhole. When a whale surfaces and shoots that famous spray of mist into the air, it’s exhaling through its blowhole.