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How do rays use spiracles to breathe?

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southern stingray (Dasyatis americana or Hypanus americanus) — chondrichthyan Southern stingrays (*Dasyatis americana* or *Hypanus americanus*) are found in the western Atlantic Ocean.

Most rays use their spiracles—a pair of modified first gill clefts located behind the eyes—as their primary intake for water during respiration.123

To breathe, rays draw water in through these spiracles, which then close via contraction at their anterior margins to prevent backflow. Folds of membrane located on the roof and floor of the mouth direct the water toward the gill openings, ensuring it does not pass down the throat. This process allows rays to respire efficiently while resting on the sea floor.1

While this is the standard method for most rays, there are exceptions:
* Mantas: Because they live near the surface and have small spiracles, they respire chiefly through their mouths.1
* Skates: These may inhale some water through the mouth while keeping the lower surface of the head slightly elevated from the bottom.1
* Cleaning: Many species, including stingrays and guitarfishes, occasionally reverse the flow of water through their spiracles to clear out foreign matter.1