niotes typically breathe by contracting and relaxing specific muscle groups (i.e. intercostals, abdominal muscles, and/or a diaphragm) attached to a rib cage that can expand and contract the body wall, letting air flow in and out of the lungs. The rigid shell of turtles is not capable of expansion, so they have had to evolve special adaptations for respiration. The lungs of turtles are attached directly to the carapace above while below, connective tissue attaches them to the organs. They have multiple lateral (side) and medial (middle) chambers (the numbers of which vary between species) and one terminal (end) chamber. The lungs are ventilated using specific groups of abdominal muscles attached to the organs which pull and push on them. Specifically, it is the turtle's large liver that compresses the lungs. Underneath the lungs, in the coelomic cavity, the liver is attached to the right lung by the root, and the stomach is directly a ttached to the left lung, which is attached to the liver by a mesentery. When the liver is pulled down, inhalation begins. Supporting the lungs is a wall or septum, which is thought to prevent them from collapsing. During exhalation, the contraction of the transversus abdominis muscle propels the organs into the lungs and expels air. Conversely, during inhalation, the relaxing and flattening of the oblique abdominis muscle pulls the transversus back down which allows air back into the lungs. Although many turtles spend large amounts of their lives underwater, all turtles breathe air and must surface at regular intervals to refill their lungs. Depending on the species, immersion periods vary between a minute and an hour. Some species can respire through the cloaca, which contains large sacs that are lined with many finger-like projections which take up dissolved oxygen from the wa