 If you've seen a praying mantis, you may have noticed how little it moves. Mantids are a lot like sloths. Because they are slow and easy to keep track of, mantids are often used in biological studies. Researchers have studied the relationship between the distance a mantid will move to seek food and the amount of food already in the mantid's stomach. We measure the amount of food already in the mantid's stomach in centigrams and the distance a mantid will travel for food in millimeters. We call the amount of food in the mantid's stomach the degree of satiation, represented by S. This measures the mantid's level of satiation or satisfaction. As the amount of food in the mantid's stomach decreases, the degree of satiation also decreases and the mantid will travel longer distances to get food. When we move food closer and closer to a mantid, the distance at which a mantid begins to move towards the food is called the maximal distance of reaction, which we label as R. As the amount of food in the mantid's stomach increases, its degree of satiation also increases and the maximal distance of reaction decreases. The mantid's hunger is so satisfied the mantid is less willing to travel to get food. At some point, the mantid's degree of satiation is so great, the mantid will not move towards the food no matter how close the food is placed to it. This is when the mantid has reached what scientists refer to as the hunger threshold. Researchers have observed the amount of food in a mantid's stomach over time in order to calculate how fast a mantid digests its food. They measure the amount of food in a mantid's stomach in centigrams and label it as S, which stands for the degree of satiation. Scientists measure the time that passes in hours and label it T. After a mantid has eaten its fill, as time passes, the amount of food in a mantid's stomach decreases. By combining the measurements from many mantid's, biologists have a fairly accurate picture of how fast mantids digest their food.