Water lungs

The water lungs are protrusions of the rectum in sea ​​cucumbers , also called sea rolls. These are located in front of the anus and are paired and tubular. In addition to breathing , they are also responsible for mineral metabolism and excretion.

The intestine has both a dorsal and a ventral vessel. There are numerous vessels on the dorsal vessel that are contractile and can function as hearts . They form a plexus from which the blood collects in a ventral vessel. The vascular network connects the intestine and the left water lung. There are numerous follicles around the water lungs where blood cells accumulate.

Water lungs are slender and tall like a tree with many shorter branches; in fact, they are tubes with thin walls. The body cavity fluid is located around the lungs. If the anus and the entrance to the water lungs are now opened, water with oxygen can enter the water lungs. The oxygen taken up from the water by the water lungs can then be released directly from the water lungs into the body cavity fluid. Water lungs are thus structures of the intestine; instead of air as in humans, water is absorbed and oxygen is then withdrawn from it.