Creatures of the land and air that breathe through lungs have a ready supply of oxygen, which makes up almost 21% of earth’s ...

When you and I take a deep breath, we pull air into our lungs. That’s because humans are mammals. But fish aren’t mammals. They usually don’t breathe air. They usually don’t have lungs. That’s what I ...

How do fish breathe underwater? -- Mordechai Linfield, 8, Silver Spring With all the talk this summer about those exotic snakeheads climbing out of ponds and trotting about in the open air, we almost ...

Fish live surrounded by water, so the idea that they might struggle to breathe sounds wrong at first. It feels like asking whether birds can fall out of the sky. Still, the question keeps coming up, ...