The turtle (individual 03) is breathing during a brief pause between locomotor bouts. This clip shows three simultaneously recorded images: the top portion of the screen shows light video, the middle shows x-ray video and the bottom shows ventilatory airflow. In this lateral view, the animal is wearing a custom-built pneumotach mask (appears dark in x-ray and light in regular video) which is attached to a differential pressure transducer and calibrated for airflow rates and volumes. The light area in the middle of the animal is the air-filled lungs. A metal marker has been glued to the skin just superficial to the abdominal muscles (transverse and oblique abdominis) which can be seen to move during breathing. In the airflow trace, zero airflow (the flat line in the middle) indicates no breathing, exhalation occurs when the trace is above zero and inhalation occurs when the trace is below zero. Note: the Y-axis (voltage) scale of the breathing trace changes during the course of the clip.
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