Chromists are usually photosynthetic organisms and are not dependent on other organisms for their nutrition. They produce their own food through photosynthesis using sunlight, carbon dioxide, and water. Therefore, they do not need to rely on other organisms as parasites do, which take nutrients from their host organism. Additionally, some chromists are also capable of heterotrophic feeding which allows them to obtain nutrients from their surroundings even when sunlight is not available. This makes them less likely to evolve into parasites, unlike other protists, which often lack the ability to produce their own food.
