Turtles use their lungs to breathe in oxygen, but when they are under water they use cloacal respiration. To accomplish cloacal respiration, the turtles pump water in and out of their pouches, which are called cloacal bursae. The pouches on the diagram labeled as 2 are the paired cloacal bursae. These are the muscles in the inguinal pocket, which expand and contract. The number 1 labeled on the diagram is the cloacal orifice where the water first enters the turtle. The number 3 shows the inner lining of the cloacal bursae, which is made of long fimbriae.