[□] | □
[□=□] | □
[□ | □] | □
Breathing with an open mouth involves holding your hand close to your mouth to feel air heated in your lungs move slowly across the skin . In the intestine , they help to move fecal material along in cooperation with a process called peristalsis ( the movement of food material by the squeezing of the intestinal muscles ) . If you can persuade your parents to have a roast leg of lamb next weekend - there 's your artiodactyl reference specimen , and your school may have a dog or cat skeleton set up in the lab - there 's your carnivore . Insufficient space has become a serious impediment to a growing number of Penn State 's academic programs . This is because direct exposure of bare skin to sunlight is what generally causes skin cancer .