How do whales breathe?

A whale’s nostrils moved to the top of its head over millions of years of evolution, forming a blowhole that lets it breathe while barely breaking the surface. Toothed whales, such as dolphins and sperm whales, have one blowhole, while baleen whales, such as blue and humpback whales, have two. The visible “spout” is mostly warm, moist exhaled breath condensing in the air, plus some seawater around the blowhole. Whales can exchange up to about 80 to 90 percent of the air in their lungs per breath, far more than humans. Their muscles store lots of oxygen in a protein called myoglobin, letting some species hold their breath for over an hour.