* They have blowholes: On top of their heads, dolphins have a pair of blowholes that act as nostrils. These are closed when the dolphin is submerged but open when it surfaces to breathe.
* They breathe air: When a dolphin surfaces, it takes a quick, forceful breath through its blowhole. This fills its lungs with fresh air.
* They hold their breath: Dolphins can hold their breath for a surprisingly long time, sometimes for several minutes. The exact amount of time depends on various factors like the dolphin's size, activity level, and water temperature.
* They use their lungs efficiently: Dolphins have a special adaptation called the "countercurrent exchange system" in their lungs. This system helps them extract more oxygen from each breath and store it in their blood for longer periods.
* They have a special muscle: Dolphins have a muscle called the "diaphragm" that helps them control their breathing and regulate their oxygen levels.
Here are some additional points about dolphin breathing:
* Dolphins do not have gills like fish; they breathe air through their lungs just like land mammals.
* They often breathe rapidly and shallowly when they are active, but they can take deeper breaths when they are resting.
* Dolphins can sleep while breathing, but they usually only sleep for short periods at a time. One half of their brain remains active while the other half rests.
In summary, dolphins are highly adapted to their aquatic environment. They have developed unique respiratory systems that allow them to efficiently absorb oxygen from the air and stay submerged for extended periods.