Their flowers come out at night because they are pollinated by insects or small animals that come out at night. Insects and small animals carry pollen from one cactus to another. Most cacti live in North and South America. Others live in Africa, Madagascar,and Sri Lanka. Cacti do not have very large leaves because large leaves would allow the water to evaporate. When water evaporates, it changes from a liquid to a gas. When it becomes a gas, it is light enough to move through the air.