Frog biology is similar in many ways to human biology, and like humans, the longest visible organ in a frog is the Small Intestine. When dissecting a frog, the skin is cut open and laid to the side, and then organs are lifted or removed in order. The order may be different depending on the curriculum, but the skin, muscle, and fat must be removed before the small intestine can be observed. Usually, the liver must be removed as well, because it is the largest structure in a frog's body, and so can cover up other organs. The small intestine is attached to the stomach and large intestine respectively, and is longer than the frog itself, coiled into a smaller space; the small intestine can be up to 3.5 times the length of the frog.